USA Bombers

Calder · Post by **Calder** » Wed Mar 15, 2023 9:04 pm

U.S. Bombers Pre-1937
Huff-Daland B-1 As early as April of 1926, the Army had decided that single-engined bombers were unsatisfactory, concluding that the more conventional twin-engined configuration was safer and had the additional advantage of allowing for a gunner and/or bomb-aiming position to be mounted in the nose. The B-1 had two gunners, one seated in the rear of each engine nacelle. Twin Lewis guns were provided for each of these gunners, with a third pair provided for a gunner's position in the nose. The Huff-Daland B-1B was powered by two 600 hp Curtiss V-1570-5 Conqueror liquid-cooled engines. Maximum speed 117 mph at sea level, service ceiling 15,000 feet, range 700 miles. Weights: 9462 pounds empty, 16,500 pounds gross, 17,039 pounds maximum. Wingspan 85 feet, length 62 feet, height 19 feet 3 inches, wing area 1604 square feet. Armed with six Lewis machine guns, paired in engine nacelle and nose positions and 2500 pound bombload

Curtiss B-2 Condor First flight of the XB-2 took place in September 1927. The Conqueror engines were housed inside nacelles mounted on top of the lower wing. A defensive gunner position was in the rear of each engine nacelle. An additional gunner position was provided in the nose. In June, 1928 Curtiss was given a contract for two B-2s with a further ten examples were ordered in 1929. The type was withdrawn from service by 1936. The Curtiss B-2 Condor was powered by two 633 hp Curtiss V-1570-7 Conqueror liquid-cooled engines. Maximum speed 132 mph at sea level, 128 mph at 5000 feet. Cruising speed 114 mph, landing speed 53 mph. Service ceiling 17,100 feet, absolute ceiling 16,400 feet. Initial climb rate 850 feet per minute. An altitude of 5000 feet could be attained in 6.8 minutes. Range was 780 miles. Empty weight 9039 pounds, gross weight 16,516 pounds. Wingspan 90 feet, length 47 feet 6 inches, height 16 feet 3 inches, wing area 1499 square feet. Armed with two Lewis machine guns in each of the gunner positions at the rear of the engine nacelles, plus an additional pair of Lewis guns in the nose position. Bombload was normally 2508 pounds, but could be increased to 4000 pounds on short flights.

Keystone B-3 The 17th production Keystone LB-6 on the 1929 contract had been completed as the LB-10. The LB-10 differed from the LB-6 in being powered by a pair of experimental 525 hp Wright R-1750-1 Cyclone radial engines, plus it had a single rudder in place of the twin rudders which Keystone had standardized on the LB-5A. However, before the first LB-10A could be delivered, the USAAC had dropped the LB designation and was listing all of its bombers under the B series. The LB-10A was redesignated B-3A. A total of 63 B-3 bombers were built. The B-3 was powered by two 525 hp Pratt & Whitney R-1690-3 Hornet air-cooled radial engines. Maximum speed 114 mph at sea level, 109.5 mph at 5000 feet. Cruising speed 98 mph. Landing speed 56 mph. Service ceiling 12,700 feet. Initial climb rate 650 feet per minute. An altitude of 5000 feet could be attained in 9.4 minutes. Range was 860 miles. Weight: 7705 pounds empty, 12,952 pounds gross. Wingspan 74 feet 8 inches, length 48 feet 10 inches, height 15 feet 9 inches, wing area 1145 square feet. Armed with three Browning machine guns, one in each of nose, dorsal, and ventral positions. A bomb load of 2500 pounds could be carried.

Keystone B-4 In 1930, seven Keystone biplane bombers were ordered under the designation LB-13. They were to be equipped with single vertical tails and were to be powered by a pair of 525 hp Pratt & Whitney GR-1690 radials. Five were completed as Y1B-4s with 575 hp R-1860-7 engines (30-344/348). On April 28, 1931, the Army ordered 25 examples of the B-4A, which was an improved production version of the Y1B-4. The B-4A was externally almost identical to the B-3A which preceded it (as well as to the B-5 and B-6 which followed it). These Keystone bombers usually differed from each other only in the type of engine which powered them, and it was often only possible to distinguish one from the other by an examination of their serial numbers. Their performance was identical.

Keystone B-5 In 1930, three Keystone biplane bombers were ordered under the designation LB-14. They were to be equipped with single vertical tails and were to be powered by a pair of 525 hp Pratt & Whitney GR-1860 radials. The LB-14s that were ordered were completed under the designation Y1B-5s with 525 hp Wright R-1750-3 engines. However, it is uncertain if these were ever actually delivered. 27 production versions of the Y1B-5 were obtained by converting existing B-3As. These conversions were assigned the designation B-5A. They were powered by a pair of Wright R-1750-3 Cyclone air-cooled radial engines.

Keystone B-6 Two LB-13s were completed as Y1B-6 with 575 hp Wright R-1820-1 Cyclone engines (30-349/350). Three more Wright-powered Y1B-6s (30-351/353) were produced by conversion from production Pratt & Whitney-powered B-3As On April 28, 1931, the Army ordered 39 B-6A bombers. The B-6A was an improved production version of the Y1B-6.

Douglas B-7 In early 1930, the Douglas aircraft company submitted a proposal to the Army for a twin-engined observation plane. On March 26, 1930, the Army ordered two example of the Douglas proposal. One was designated XO-35 and the other XO-36, the primary difference being that the XO-35 had two geared 600 hp Curtiss V-1570-29 Conquerors driving three-bladed propellers and the XO-36 had two direct-drive 600 hp Curtiss V-1570-23 Conquerors driving two-bladed propellers. The performance of the XO-35/36 promised to greatly exceed that of the lumbering Keystone biplanes that were at that time the standard USAAC light bombers. Consequently, the Army decided to have the XO-36 completed as a light bomber rather than as an observation plane. It was assigned the designation XB-7, and was to have been equipped with racks for 1200 pounds of bombs underneath the fuselage. On August 22, 1931, the USAAC ordered seven Y1B-7 bombers and five Y1O-35s, these being delivered between August and November of 1932. The Y1B-7 was powered by two 640 hp Curtiss V-1570-33 or 675 hp V-1570-52 Conqueror twelve-cylinder liquid-cooled Vee engines. Maximum speed: 182 mph at sea level, 177 mph at 5000 feet. Cruising speed: 155 mph. Landing speed 78 mph. Climb to 5000 feet in 3.7 minutes. Climb to 10,000 feet in 8.7 minutes. Service ceiling 20,400 feet, absolute ceiling 21,800 feet. Normal range 411 miles, maximum range 632 miles. Weights: 5519 pounds empty, 9953 pounds loaded, 11,177 pounds maximum Dimensions: wingspan 65 feet, length 45 feet 11 inches, height 11 feet 7 inches, wing area 621.2 square feet. Armed with two 0.30-inch machine guns, one in a flexible nose position and the other in a flexible dorsal position. 1200 pounds of bombs could be carried on racks underneath the fuselage.

Fokker XB-8 In 1929, the Fokker design department developed an observation aircraft that could replace the Douglas O-25. This was a true cantilever monoplane with no struts or rigging wires. The plywood-covered high-mounted wing was made of wooden box spars with plywood spars and ribs, covered with a plywood veneer. The fuselage was made of steel tubing and was covered with fabric. The aircraft was powered by a pair of Curtiss V-1570-9 Conqueror twelve-cylinder liquid-cooled engines mounted in the leading edge of the wing. The landing gear was retractable, the first such to be fitted to an Army Air Corps observation or bombardment aircraft. Three crew members (1 pilot plus two gunners) could be carried in open cockpits. Armament was to consist of two flexible 0.30-inch machine guns, one operated by a gunner in a nose position and the other by a gunner in a dorsal position. In 1929 the Army decided to have the second prototype of both designs completed as a light bomber rather than as an observation plane. The designation XB-8 was assigned to the Fokker design. On April 11, 1931, the company received a contract for six service test B-8s. This was subsequently reduced to a single aircraft, the type proving inferior to the B-7.

Boeing B-9 The Boeing B-9 was the first cantilever monoplane bomber to be produced for the US Army. low-winged, all-metal cantilever monoplanes. The fuselage was of semi-monocoque construction, which permitted the use of a more nearly circular cross section. The main landing gear retraced rearward into the engine nacelles, but the lower halves of the wheels remained exposed.

Five crew members were carried—pilot, copilot, nose gunner/bombardier, rear gunner, and a radio operator. Four of the crew members sat in separate open cockpits, widely separated from each other. The bombardier/nose-gunner sat in a cockpit in the nose, which was equipped with a bomb sight and aiming window in the bottom and had a mount for a single flexible 0.30-inch machine gun around the top. Because the fuselage was so narrow, the pilot and copilot sat in separate tandem cockpits immediately behind the nose gunner. A fourth cockpit for a rear gunner was located on top of the fuselage behind the wing. He operated a single flexible 0.30-inch machine gun. The radio operator was located inside the fuselage just ahead of and below the pilot, and had a window on each side of the nose. Because of their wide separation, crew members had difficulty in communicating with each other in flight. The pilot had limited visibility because of the radial engines on each side and the long forward fuselage immediately ahead. The Army ordered five new planes under the designation Y1B-9A. The B-9 was a truly revolutionary design, and had a speed fully 60 percent greater than that of the Keystone biplane bombers that were still the backbone of the American bomber force in 1932. In war games held in May of 1933, the Y1B-9A could not be intercepted by six Boeing P-12 fighters, giving the USAAAC a bomber with a performance superior to that of its pursuit aircraft. In view of its superior performance, Boeing fully anticipated an Army order for substantial numbers of the new design. However, The Glenn L. Martin company in Baltimore, Maryland had in the meantime brought out a competing design of its own that had a substantially better performance. The Army decided to order the Martin design into production under the designation B-10 and B-12, and no production examples of the B-9 were ordered.

Martin B-10

Douglas B-11 The Douglas B-11 was a 1932 project for an amphibian bomber that would fly over water along with formations of conventional land-based bombers to act as navigation leaders and as rescue aircraft in case one of the bombers went down. The idea was abandoned.

Martin B-12

Martin B-13

Martin B-14

Boeing XB-15 In April 14, 1934, the Army Air Corps issued a request for a long-range bomber. A 5000 mile range with a 2000-pound bombload was envisaged.

The Boeing Airplane Company submitted its Model 294 in response to this requirement. The Army expressed sufficient interest in the Model 294 that it issued a contract on June 28, 1934 for design data, wind-tunnel tests, and the construction of a mockup under the designation XBLR-1, the letters standing for "Experimental Bomber, Long Range". On June 29, 1935, a contract was approved for one example of the XBLR-1. The BLR category was later eliminated, and the aircraft was redesignated XB-15 in July 1936.

The XB-15 was a large, four-engined mid-wing cantilever monoplane with all-metal semi-monocoque construction. The structure was generally similar to that of earlier Boeing monoplanes that had been based on the Monomail design, with the exception that the wing from the main spar aft was covered with fabric instead of metal. The XB-15 was originally to have been powered by four Allison V-1710 liquid cooled V-12 engines. However, before the aircraft was built, the powerplants were changed to four 1000 hp Pratt & Whitney R-1830 twin-row air-cooled radials. The defensive armament was the heaviest yet to be fitted to a bomber. It carried six machine guns. One of these guns was mounted in a nose turret and another one was carried in a forward-facing belly turret mounted below the pilot's cabin. A 0.50-inch gun was mounted in a top turret which could rotate through 360 degrees. One gun was carried in each of two waist blisters attached to the fuselage behind the wings. A sixth gun was housed inside a rearward-facing belly turret. The XB-15 proved to be seriously underpowered with the R-1830 radials. Because of its low performance as compared to later aircraft, the XB-15 was never ordered into production, and the prototype was the only example to be built

The XB-15 was powered by four Pratt & Whitney R-1830-11 Twin Wasp air cooled radials, rated at 850 hp at 2450 rpm at 5000 feet, and 1000 hp for takeoff. Maximum speed: 200 mph at 5000 feet, 197 mph at 6000 feet, cruising speed 152 mph at 60 percent power at 6000 feet. Service ceiling 18,900 feet, absolute ceiling 20,900 feet. Climb to 5000 feet in 7.1 minutes, climb to 10,0000 feet in 14.9 minutes. Range 3400 miles with 2511 pounds of bombs, maximum range 5130 miles. Weights: 37,309 pounds empty, 65,068 pounds gross, 70,706 pounds maximum. Dimensions: wingspan 149 feet, length 87 feet 7 inches, height 18 feet 1 inches, wing area 2780 square feet. Armed with two 0.50-inch and four 0.30-inch machine guns. A bomb load of four 2000 pound bombs could be carried. Maximum bombload was 12,000 pounds.

Martin XB-16 In April 14, 1934, the Army Air Corps issued a request for a long-range bomber. A 5000 mile range with a 2000-pound bombload was envisaged. The Glenn L. Martin Company of Baltimore, Maryland submitted its Model 145, a large cantilever monoplane powered by four Allison V-1710 liquid-cooled V-12 engines. This was later enlarged to a 173-foot wingspan aircraft powered by six Allison V-1710-2 engines, four of them operating as tractors and two as pushers. Twin rudders were to have been mounted behind two tail booms. A tricycle landing gear was to be used. The maximum weight was to have been 105,000 pounds. The Martin XB-16 was considered as being too large and expensive, and the project was cancelled before anything could be built.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:04 pm

US Army/Airforce Bombers 1940-2004
Boeing B-17 Flying Fortress Four-engine heavy bomber. Four Wright R-1820 Cyclone radials. Production severely cut back in wake of 1940 decision to concentrate on bombers with transoceanic range

Douglas B-18 Bolo Adaptation of DC-2 commercial transport to bombing role

Douglas XB-19 Four-engined long-range heavy bomber. Four Wright R-3350-5 radials. Small number (circa 20) built as TB-19 to provide interim trainers and cadre aircraft prior to availability of B-36

Boeing YB-20 Experimental four-engine long-range bomber. Only one built. Proposed version with 1400 hp Pratt and Whitney R-2180 radial engines canceled before any prototype could be completed.

North American XB-21 Twin-engine medium bomber. Two P & W R-2180 Twin Hornets with superchargers. Crew of six. Five 0.30-cal guns in power turrets in nose and on top, and at mounts in waist and ventral positions. Only one built.

Douglas XB-22 Proposed adaptation of B-18 to take two Wright R-2600 radials. Cancelled in favor of B-23.

Douglas B-23 Dragon Twin-engine medium bomber.

Consolidated XB-24 Liberator Four-engine heavy bomber. Four Pratt and Whitney R-1830 radial engines on high-mounted wing. One prototype built, production order cancelled.

North American B-25 Mitchell Twin-engine medium bomber. Two Wright R-2600 Cyclone radial engines. Total of 9816 built.

Martin B-26 Marauder Twin-engine medium bomber. Two P & W R-2800 radials. High-mounted wing. Streamlined cigar-shaped fuselage

Martin B-27 Super-Marauder High-altitude adaptation of B-26. Two turbo- supercharged P & W R-2800 Wasps. Pressurized cabin. Replaced B-25 and B-26 from 1945 onwards. Also supplied to Russia under lend-lease. Served until early 1950s. Many supplied to other countries most notably India. Last examples not withdrawn from non-US service until early 1970s.

North American XB-28 Hillbilly High-altitude adaptation of B-25. Two turbo- supercharged P & W R-2800 Wasps. Pressurized cabin. Single rudder. Cancelled in favor of B-27 and only two were built

Boeing B-29 Superfortress Long range, high altitude heavy bomber. Four Wright R-3350 radials. Unbroken nose, crew of 11, pressurized cabin. Four remote-controlled turrets, plus tail gun position. Planned production cut back dramatically in favor of B-36.

Lockheed XB-30 Long range, high altitude bomber. Proposed bomber version of Constellation airliner. Entered in competition which eventually produced the B-29, but Lockheed withdrew from the contest before any prototypes could be built

Douglas XB-31 Long-range, high altitude bomber designed in competition with Boeing B-29. Canceled in favor of B-29 before any prototypes could be built.

Consolidated XB-32 Dominator Proposed long-range bomber, cancelled to allow Convair to concentrate on B-36.

Martin B-33 Long range bomber project with four 1800 hp R-2600 radials and twin tails. Cancelled due to poor performance but redesigned as a short-range heavy bomber intended to replace the B-17 in interdiction and tactical support roles. Single tail, powered by four R-2800s. Production was limited due to the Martin plants being swamped by production of B-26 and B-27 aircraft.

Lockheed B-34 Ventura Midwing twin-engine medium bomber with twin rudders. Military adaptation of Model 18 Lodestar airliner. Limited production in early 1940s mostly assigned to Navy for ASW patrols

Northrop YB-35 Long-range flying-wing bomber competitor to B-36. Four P & W R-4360 radials with double turbosuperchargers driving pusher propellers. Cancelled due to technical problems, excessive cost and poor performance.

Convair B-36 Peacemaker Six-engine long-range heavy bomber. Six P & W R-4360 radials driving pusher props. D version had four General Electric J-47 jets in pods under outer wing to increase over-target speed. Primary striking force of US SAC from 1944 to 1956. More than 6,000 built. Remained in service until 1958.

Lockheed B-37 Ventura Adaptation of B-34 Ventura for ASW role with R-2600 engines.

Lockheed-Vega XB-38 B-17E airframe converted by Vega division of Lockheed to take four Allison V-1710-89 liquid-cooled engines. Only one built.

Boeing XB-39 Superfortress Conversion of B-29 airframe to take four Allison V-3420 liquid-cooled engines of 3000 hp. Each following massive B-29 losses in 1944/45 bombing raids. Cancelled due to inadequate range/speed/altitude profile.

Boeing YB-40 Conversion of B-17E as escort bomber to improve defensive power of B-17 bomber formations.

Boeing YB-41 Escort bomber conversion of B-29. Eighteen 0.50 cal guns. Small number built, has unique distinction of entire production run being shot down by enemy fighters.

Douglas XB-42 High-speed long-range medium bomber. Two Allison V-1710-125 water-cooled engines buried in fuselage driving pusher propellors behind the tail. Only two built.

Douglas XB-43 First American jet bomber. XB-42 airframe fitted with two turbojets in forward fuselage bays fed by intakes located behind the cockpit. Lower tail fin eliminated, taller vertical tail. Two built.

Boeing XB-44 B-29A with four P & W R-4360 radials in redesigned nacelles. Became prototype for B-50. Three built.

North American B-45 Tornado Four-jet medium bomber. First all-jet powered bomber to enter service with USAF. The B-45 entered service in 1948 and was phased out by the early 1950s. It was just a little too late to see service in WW2 and it was a casualty of the general decline of tactical aviation in the 1950s. The survivors were operated briefly by NORAD and were replaced by F-100s. Four General Electric J-47 jets.

Convair XB-46 Four-jet medium bomber. Four General Electric J-35 jets. 491 mph at sea level. Lost out to B-45 Tornado for production orders primarily to avoid interrupting B-36 production

Boeing XB-47 Stratojet Proposed six-jet swept-wing medium bomber. Six General Electric J-47 jets. Never used by air force but 500 built for Navy as land-based maritime bombers under designation PB2B-2 Sinatra

Martin XB-48 Six-jet medium bomber. Six Allison J-35 jets mounted three each in underwing pods. Cancelled in favor of B-47 only two built

Northrop YB-49 Conversion of B-35 to all-jet power. Eight Allison J-35 jets. Wing fences and vertical stabilizing fins were added. All turrets and guns were eliminated. Complete technical failure, expensive, unstable and difficult to fly. Program was canceled in 1949 in favor of further production of B-36.

Boeing XB-50 Superfortress Proposed adaptation of B-29 to accommodate four P & W R-4360 radials of 3500 hp each housed in modified nacelles. Enlarged vertical tail. Cancelled due to lack of operational requirement but design was licensed to Tupolev Design Bureau who built over 1,000 as Tu-4. These served with Russian long-range aviation and naval aviation.

Martin XB-51 Three-jet light bomber. Three General Electric J-47 jets, two under forward fuselage and one in tail. Cancelled due to lack of operational requirement

Boeing B-52 Stratofortress Eight-jet long-range strategic bomber. Eight P & W J-57 engines mounted in four pods underneath swept- back wings Total of 3744 built.

Convair XB-53 Three-jet light bomber project. Canard design with swept-forward wing. Three J-35 jets. Was formerly XA-44. Canceled before completion.

Boeing XB-54 Proposed version of B-29 with P & W R-4360-51 compound engines. Canceled in favor of B-36 before any prototype could be completed. One built in Russia as Tu-8 but cancelled in favor of turboprop powered Tu-95

Boeing XB-55 Long-range heavy bomber powered by four Allison T-40 turboprops housed in pods under a slightly swept- back wing. Abandoned before prototype could be completed because of greater promise of B-52. ASW development offered to Navy but declined in favor of P3V

Boeing XB-56 Version of B-47 with four Allison J-71 jets. Project was canceled before prototype could be completed. Offered to Navy, declined in favor of PB5Y version of B-58

Martin XB-57 Twin-jet light bomber to replace B-45. Never built due to lack of operational requirement.

Convair RB-58 Hustler Four-engine supersonic strategic reconnaissance bomber replacing RB-36 and RB-52. Four General Electric J-79 jets with afterburners in individual pods under a delta wing on RB-58A to RB-58D. Four unreheated J-58s on RB-58E to RB-58K

Boeing XB-59 Supersonic bomber project powered by four General Electric J-73 engines. Lost out to Convair B-58 for Air Force orders. Never got off the drawing board.

Convair B-60 Devastator Jet-powered version of B-36. Eight J-57 jets, swept wing and tail. Withdrawn from nuclear strike role by 1960 but served as conventional bomber for SAC until early-1970s.

Martin XB-61 Matador Single-engine ground-launched cruise missile. Cancelled in 1957 "Missile Massacre"

Northrop XB-62 Snark Single-engine ground-launched strategic cruise missile. The discovery that one of these missiles fired on a test had hit the wrong continent sparked off the 1957 "Missile Massacre". Cancelled in 1957

Bell XB-63 Rascal Air-launched strategic missile. Cancelled in 1957 "Missile Massacre"

North American XB-64 Navajo Ground-launched strategic supersonic cruise missile. Cancelled in 1957 "Missile Massacre"

Convair XB-65 Atlas Ground-launched intercontinental ballistic missile. Cancelled in 1957 "Missile Massacre" but subsequently developed as satellite booster.

Douglas B-66 Destroyer Air Force adaptation of carrier-based A3D Skywarrior light bomber. Two Allison J-71 jets. Bomber, reconnaissance, and electronic countermeasures versions produced but the B-66 program was a casualty of the general decline of tactical aviation in the 1950s. The small force was operated by NORAD. Total of 294 built.

Martin XB-67 Titan Ground-launched intercontinental ballistic missile. Cancelled in 1957 "Missile Massacre" but subsequently developed as satellite booster.

Martin XB-68 Two-seat tactical bomber powered by two P & W J-75 engines. High T-tail and rotary bomb door. Canceled in 1957 in favor of F-105.

Boeing XB-69 Minuteman Ground-launched intercontinental ballistic missile. Cancelled in 1957 "Missile Massacre"

North American B-70 Valkyrie Mach 3 strategic bomber. Six General Electric J-93 engines. Delta wing. Twin rudders. Mainstay of SAC bomber groups until early 21st century. Over 3,000 built

Lockheed B-71 Blackbird Light bomber version of Lockheed SR-71 and RS-71 twin-engined Mach 3+ strategic reconnaissance aircraft. Became part of “Air Commando” units responsible for finding and destroying mobile strategic targets.

Douglas XB-72 Thor Intermediate range ballistic missile Cancelled in 1957 "Missile Massacre"

Martin XB-73 Titan II Ground-launched intercontinental ballistic missile. Proposed development of XB-67 Cancelled in 1957 "Missile Massacre" but subsequently developed as satellite booster.

Convair B-74 Dominator Very large six-engined conventional bomber replacing B-60. Not assigned nuclear delivery roles. Remained in limited service until around 2010

Boeing XB-75 Minuteman II Proposed ground-launched intercontinental ballistic missile development of XB-69. Cancelled in 1957 "Missile Massacre"

Lockheed XB-76 Polaris Proposed sea launched ballistic missile being developed for US Navy. Reason for designation in USAF bomber sequence is unknown. Cancelled in 1957 "Missile Massacre"

North American B-77 Hound Dog Long-range stand-off missile deployed on B-52B to B-52G

Chrysler XB-78 Jupiter Joint Army/Air Force intermediate range ballistic missile. Cancelled in 1957 "Missile Massacre" but subsequently developed as satellite booster.

Martin B-79 White Lance Long-range stand off cruise missile deployed on RB-58

Boeing XB-80 Minuteman III Concept design for ultimate ground-launched intercontinental ballistic missile development of XB-69. Cancelled in 1957 "Missile Massacre"

Lockheed B-81 Agena Air-launched ballistic missile carried in bomb bay of B-52D – G

Martin XB-82 Lone Star Competitor to B-81. Cancelled.

Teledyne B-83 Quail Decoy missile deployed on B-52

Teledyne B-84 Grouse Decoy missile deployed on B-58

Teledyne B-85 Pigeon Decoy missile deployed on B-70 and B-71

Douglas B-87 Skybolt Air-launched ballistic missile deployed on B-52

Convair XB-88 Proposed development of B-74 Dominator. Cancelled.

Thiokol B-89 Short range attack missile used on B-52, B-58, B-70 and B-71.

Convair B-90 Airhawk Long range air-launched cruise missile

Note. Designations B-91 to B-99 apparently not used. May refer to proposed variants developed from Dyna-Soar program

North American YGB-100 Large mothership aircraft derived from B-70 Valkyrie, intended as re-usable first stage of surface-to-space (aerospace) fighters and bombers until multi-mode engines perfected.

Boeing B-100 Dynasoar Manned orbital strategic bomber. Surface-based using YGB-100 manned first stage or based on Manned Orbiting Weapons System (MOWS Space Station)

North American XB-101 Robo Manned orbital strategic bomber and space exploration craft. Surface-based using YGB-100 manned first stage or based on Manned Orbiting Weapons System (MOWS Space Station)

North American B-101A Robo. Despite similarity of designation, had only marginally commonality with XB-101. Powered by four turboscramrockets to give single stage to orbit. First flew 1989 but lengthy technical development delayed service entry until 2001.

North American B-103 Valkyrie. Highly developed version of B-70 Valkyrie with turboscramjets based on J-93 engines. First entered service 1998. Replacing B-70 in squadron service.

Lockheed-Boeing RB-104 Vulture. Turboscramrocket single-stage-to-orbit bomber to replace RB-58 series. Started entering service 1998

Bell-Martin GRB-105 Phoenix Manned orbital strategic reconnaissance and space exploration craft based on Dynasoar. Surface-based using YGB-100 manned first stage or based on Manned Orbiting Weapons System (MOWS Space Station). Limited replacement for SR-71 aircraft. Entered service in 1985, replaced from 2000 onwards by RB-107

North American B-106 Aurora Developed single-stage to orbit version of the B-103 with turboscramrockets giving it sub-orbital attack capability. Entering service 2006.

Bell-Martin RB-107 Phoenix Advanced derivative of the GRB-105 equipped with Turboscramrockets to give single stage to orbit capability. Replaced GRB-105, SR-71 and RS-71 aircraft from 2000.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:05 pm

Martin B-10
Introduction
The Martin B-10 was the first all-metal monoplane bomber to enter full production for the US Army. It was also the first bomber to have a performance that exceeded that of contemporary pursuit aircraft.

Early Development
The immediate ancestor of the B-10 was the Martin Model 123, which was designed and built as a private venture by the Glenn L. Martin Company of Baltimore, Maryland. It was a midwing all-metal monoplane. The monocoque fuselage had corrugated top and bottom surfaces with a deep belly. The deep belly carried doors for an internal bomb bay, so the bombs could be carried internally rather than on external racks. The main landing gear retracted backwards into the rear of the engine nacelles, but the lower half of the wheels remained exposed. Four crew members were to be carried. Three of the crew members were seated in separate open cockpits on the top of the fuselage. The nose gunner/bombardier had a transparent aiming position in the lower nose, the pilot sat in an open cockpit abreast of the forward wing, and the rear gunner sat in an open position in the rear dorsal fuselage. The fourth crew member occupied a position inside the fuselage.

The Model 123 flew for the first time at Baltimore on February 16, 1932. It was powered by a pair of 600 hp Wright SR-1820-E Cyclone engines that were enclosed by NACA low-drag cowling rings. The wingspan was 62 feet 2 inches. The Model 123 was delivered to the Army on March 20, 1932. Trials began in July, 1932, during which a maximum speed of 197 mph was recorded at an altitude of 6000 feet. This was a truly spectacular performance for 1932. As a result of these trials, the open-cockpit gun position in the nose was replaced by a transparent, manually-rotated gun turret equipped with a single 0.30-inch machine gun. The pilot's cockpit and the dorsal gunner position remained open. At the same time, more powerful 675 hp R-1820-19 Cyclone engines were installed. These engines were also fitted with full cowlings that extended forward of the wings. A new longer-span wing was fitted, increasing the wingspan to 70 feet 7 inches. Despite an increase of nearly 2000 pounds in the gross weight to 12,230 pounds, the modified aircraft had a maximum speed of 207 mph at 6000 feet making it was faster than any US fighter then in service. On January 17, 1933, the Army ordered 48 production examples of the Martin design under the designation B-10.

The first 14 aircraft were designated YB-10. They were powered by 675 hp Wright R-1820-25 engines. They differed from the prototype primarily in having transparent sliding canopies fitted over both the pilot's cockpit and the rear gunner's position, a concession to the 200 mph-plus speeds that could be attained. The rear cockpit was modified to accommodate a radio operator in addition to the gunner. Armament consisted of a 0.30-inch Browning machine gun in the nose turret, a 0.30-inch gun in a flexible position in the dorsal position, plus a 0.30-inch machine gun in a tunnel position in the fuselage floor behind the bomb bay to guard against attacks from below. The internal bomb bay could carry two 1130-pound bombs or five 300-pound bombs. There were provisions for an external shackle under the right wing for a single 2000 pound bomb. The first YB-10 was delivered to Wright Field in November, 1933. Most of the YB-10s were based at March Field in California with the 7th Bomb Group until December, 1934, when it re-equipped with B-12s. The YB-10s then remained at March Field with the 19th Bomb Group. A turbocharged version of the YB-10 was designated the YB-10A but this proved too unreliable for service.

Variants
Martin B-10B
Production of the Martin bomber was continued by FY 1934 and 1935 Army procurements for a total of 103 examples of the B-10B, the primary service version. The B-10B could be distinguished from the YB-10 by the presence of air intakes on top the nacelle as well as by the relocation of the exhaust pipes from the lower nacelle to outlets at the nacelle top immediately behind the air intakes. It was otherwise quite similar to the service test YB-10. The first B-10B arrived at Wright Field in July 1935. Production deliveries to Langley Field began in December 1935 and were completed by August 1936. The B-10B served with the 2nd Bomb Group at Langley and the 9th at Mitchell Field. The B-10B served (along with YB-10s) with the 19th Bomb Group based at March Field in California. The B-10B also served with the 6th Bomb Group based in the Canal Zone, and was issued to the 28th Bomb Group based in the Philippines.
In January of 1931, the US Army was assigned the responsibility for coastal defense around the United States mainland. The B-10s remained in service with Army bombardment squadrons until the advent of the B-17 and B-18 in the late 1930s. The advances in bomber technology suddenly became so rapid that the B-10, revolutionary though it was, swiftly became obsolete as the 1930s progressed. By 1940, the B-10B was thoroughly out of date and had been largely relegated to secondary roles such as target towing. No US Army B-10Bs participated in any combat during World War 2.

Specification of Martin B-10B:
Two Wright R-1820-33 Cyclone air-cooled radial engines, rated at 775 hp for takeoff and 750 hp at 5400 feet. Maximum speed 213 mph at 10,000 feet, 196 mph at sea level. An altitude of 5000 feet could be attained in 3.4 minutes. Cruising speed 193 mph. Landing speed 65 mph. Service ceiling 14,200 feet. Normal range 590 miles, maximum range 1240 miles, ferry range 1830 miles. Weights: 9681 pounds empty, 14,600 pounds gross, 16,400 pounds maximum. Dimensions: wingspan 70 feet 6 inches, length 44 feet 9 inches, height 15 feet 5 inches, wing area 678 square feet. One 0.30-inch Browning machine gun in nose turret, one 0.30-inch Browning machine gun in flexible mount in dorsal gunner position, and one 0.30-inch Browning machine gun in a ventral tunnel position mounted in the floor of the fuselage behind the bomb bay. 2260 pounds of bombs could be carried.

Martin B-12
The Martin B-12 was a production version of the B-10 that was powered by the Pratt & Whitney Hornet radial instead of the Wright Cyclone. It was common in those days to assign different USAAC model numbers to aircraft of a given type which differed from each other only in the type of engines which powered them. The first YB-12 appeared in February of 1934. Despite their new model number, they were otherwise quite similar to the YB-10. They could be externally distinguished from the B-10 version by the presence of oil cooler intakes on the port side of the engine nacelles. Internally, the B-12A had provision for an extra fuel tank in the bomb bay. This tank had a capacity of 265 US gallons, supplementing the 226 US gallons normal fuel capacity on long flights.

Specification of Martin B-12:
Two Pratt & Whitney R-1690-11 Hornet air-cooled radial engines, rated at 700 hp at 6500 feet. Maximum speed 212 mph at 6500 feet, 190 mph at sea level. Initial climb rate 1740 feet per minute. An altitude of 10,000 feet could be attained in 10.1 minutes. Cruising speed 170 mph. Landing speed 71 mph. Service ceiling 24,600 feet. Absolute ceiling 26,600 feet. Normal range 524 miles, maximum range 1360 miles, Weights: 7728 pounds empty, 12,824 pounds gross Dimensions: wingspan 70 feet 6 inches, length 44 feet 9 inches, height 15 feet 5 inches, wing area 678 square feet. One 0.30-inch Browning machine gun in nose turret, one 0.30-inch Browning machine gun in flexible mount in dorsal gunner position, and one 0.30-inch Browning machine gun in ventral tunnel. 2260 pounds of bombs could be carried.

Martin XB-13
The Martin B-13 was a proposed version of the YB-10 powered by a pair of 650 hp Pratt & Whitney R-1860-17 engines. Twelve examples were ordered but were all cancelled before delivery.

Martin XB-14
The Martin XB-14 was a version of the YB-10 powered by a pair of 950hp Pratt & Whitney YR-1830-9 Twin Wasps. Only one example of this version was built.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:05 pm

Boeing B-17 Flying Fortress
Introduction
The B-17 Flying Fortress is often neglected by histories of the American heavy bomber force that ended the Second World War yet it was this aircraft that the early bomber crews used to develop the tactics and technologies that culminated in The Big One. A total of 945 Fortresses was built before production came to an end in August 1943. Despite its brief service and limited numbers, the B-17 achieved a reputation as being capable of absorbing a tremendous amount of battle damage and still continuing to fly. Significantly, by the standards of its day, it had an excellent high-altitude performance. It was able to win the affection of the crews who flew in it, since it was often able to bring them home safely when other aircraft would have fallen.

Early Development
The origin of the Boeing Fortress can be traced to a February 1934 Army Air Corps requirement for a bomber with a range of 5000 miles at 200 mph while carrying a bombload of 2000 pounds. This became known as "Project A", and was more of a feasibility study than it was a serious proposal for a production bomber. However, there was always a possibility that production examples would be ordered if the design proved successful. Both Martin and Boeing submitted preliminary designs in response to the "Project A" requirement. The Martin project was cancelled before anything could be built, but the Boeing design (assigned the company designation of Model 294) was awarded a contract for a single example under the designation XBLR-1. The XBLR-1 was later redesignated XB-15.

In May 1934, the Army announced another bomber competition. This time, it was for a multi-engined bomber capable of carrying a ton of bombs at more than 200 mph over a distance of 2000 miles. As opposed to the "Project A" requirement, this Army requirement envisaged from the start that the winning design would have a production run of as many as 220 planes. Several manufacturers (including Boeing) were invited to submit bids, with the entries being flown at Wright Field in a final competition to select the winner. Preliminary work by Boeing on the design began on June 18, 1934. Boeing engineers came up with what was basically a scaled-down version of the Model 294. Like the Model 294, it was to be powered by four engines. Four-engined bombers were a novelty at the time, most contemporary bomber designs having only two engines. Construction began on August 16, 1934 under the company designation Model 299.

The Model 299 was based heavily on the company's experience with the all-metal Model 247 commercial airliner. It was basically a marriage between the aerodynamic and structural features used by the Model 247 and the basic four-engined format used by the Model 294 bomber. The aircraft was to be powered by four 750 hp Pratt & Whitney R-1690-E Hornet nine-cylinder air-cooled radials, each driving a three-bladed propeller. The large, thick-section wing was to be mounted low on the cylindrical-section fuselage. The main landing gear was to retract forward into the inner engine nacelles, with the lower edge of the wheel protruding into the airstream.

The Model 299 aircraft carried a crew of 8, a pilot, copilot, bombardier, navigator/radio operator, and four gunners. There were four blister-type flexible machine gun stations, each of which could accommodate a 0.3-inch or 0.5-inch machine gun. One was in a dorsal position in the fuselage just above the wing trailing edge, a second was in a ventral fuselage position just behind the wing trailing edge, and a blister was mounted on each side of the rear fuselage in a waist position. There was an additional station for a machine gun in the nose. All of the guns were manually swung. Up to eight 600-pound bombs could be carried internally. Loaded weight was 43,000 pounds. First flight of the Model 299 took place on July 28, 1935 at Seattle with Boeing test pilot Leslie R. Tower at the controls. According to legend, a reporter having seen the 299 for the first time remarked, "Why, it's a flying fortress!". The name stuck.

After a short period of factory testing, the Model 299 was flown by Boeing test pilot Leslie Tower and three other crewmen out to Wright Field on August 20 for Air Corps evaluation. During this flight, it flew the 2100 miles nonstop at an average speed of 232 mph at an average altitude of 12,000 feet, breaking all records for the distance. On October 30, 1935, the Model 299 crashed during takeoff at Wright Field and burned. Three of the crewmen managed to crawl out of the wreckage with only minor injuries, but pilot Ployer P. Hill (chief of Wright Field's Flight Testing Section) and Boeing test pilot Leslie Tower (who was riding as an observer) both died later of their injuries after being dragged from the burning aircraft. An investigation later showed that the crash was caused by the crew forgetting to unlock the tail surfaces before takeoff, the aircraft losing control immediately after leaving the ground.

Specification of Boeing XB-17
Four Pratt & Whitney R-1690E S1EG Hornet radials rated at 750 hp at 2250 rpm at 7000 feet. Performance: Maximum speed 236 mph at 10,000 feet. Cruising speed 204 mph. Service ceiling 24,620 feet. Range 2040 miles with 2573 pounds of bombs. Maximum range 3101 miles. Dimensions: Wingspan 103 feet 9 3/8 inches, length 68 feet 9 inches, height 14 feet 11 15/16 inches, wing area 1420 square feet. Weights: 21,657 pounds empty, 32,432 pounds normal loaded, 38,053 pounds maximum. Armament: Armed with five 0.30-inch machine guns, with one gun in each of nose, dorsal, ventral, and two waist positions. A maximum of eight 600 pound bombs could be carried in an internal bomb bay.

Variants
Boeing Y1B-17
The Y1B-17 was the initial service test version of the B-17, thirteen of which had been ordered on January 17, 1936. It had initially been designated YB-17, but this was changed to Y1B-17 on November 20, 1936, indicating procurement from "F-1" funds rather than from regular appropriations. The Y1B-17 was basically similar to the Model 299, but had four Wright GR-1830-39 (G2) Cyclone radials in place of the Pratt & Whitney Hornet radials of the Model 299 prototype. The Cyclone was to remain the standard powerplant all throughout the long production run of the Fortress. The crew was reduced to six, and minor changes were made in armament details and in the undercarriage. Perhaps the most readily-noticeable difference was in the the main landing gear, which now had only one leg rather than two. A long carburetor intake on top of the engine nacelles distinguished the Y1B-17 from later models. The first Y1B-17 (36-149) flew on December 2, 1936. All Y1B-17s were delivered between January 11 and August 4, 1937. Twelve of the Y1B-17s were delivered to the 2nd Bombardment Group based at Langley Field, Virginia for evaluation. The thirteenth Y1B-17 was delivered to Wright Field for experimental tests. At this time, the dozen Y1B-17s of the 2nd Bombardment Group comprised the entire heavy bombardment strength of the United States.

The 2nd Bombardment Group spent its time working out the bugs in the B-17. One of the recommendations that they came up with at an early stage was the use of a check list that the pilot and copilot would go through together before takeoff, hopefully preventing accidents such as the one which resulted in the loss of the Model 299. The author of this policy was a young Lieutenant named Curtis Emerson LeMay. Lieutenant LeMay was also the chief navigator for the first international flight by a U.S. strategic bomber group when six planes of the 2nd Bombardment group took part in a good will flight from Langley to Buenos Aires, Argentina, taking off from Langley on February 15, 1938 and returning on February 27. They covered a total of 12,000 miles without serious incident.

In May 1938, Curtis LeMay was again head navigator when Y1B-17s of the Langley-based 2nd Bombardment Group took part in a demonstration in which they "intercepted" the Italian liner *Rex* while it was still 700 miles out to sea. This was meant not only as a demonstration of the Y1B-17's superior range and navigational capabilities, but was also meant to show how useful the plane could be in attacking an enemy invasion force before it came close enough to American shores to do any damage. The Navy was not at all amused by this particular demonstration, and was furious about what it perceived to be an Army intrusion into the Navy's particular mission. Shortly thereafter, a War Department order came down restricting the activities of the Army Air Corps to within a 100-mile range of the US shoreline. The Y1B-17s flew for three years without a serious accident, and were transferred to the 19th Bomb Group at March Field in October 1940.

Specification of Boeing Y1B-17:
Four Wright R-1820-39 Cyclone radials rated at 930 hp for takeoff, 850 hp at 5000 feet, 775 hp at 14,000 feet. Performance: Maximum speed 256 mph at 14,000 feet. Landing speed 70 mph. Cruising speed 217 mph at 70 percent power. Service ceiling 30,600 feet. An altitude of 10,000 feet could be attained in 6.5 minutes. Normal range 1377 miles. Range with 4000 pounds of bombs was 2400 miles and 3320 miles with no bombs. Dimensions: Wingspan 103 feet 9 3/8 inches, length 68 feet 4 inches, height 18 feet 4 inches, wing area 1420 square feet. Weights: 24,465 pounds empty, 34,880 pounds normal loaded, 42,600 pounds maximum. Armament: Armed with five 0.30-inch machine guns with 1000 rpg. One gun was mounted in each of nose, dorsal, ventral, and two waist positions. A maximum bombload of 8000 pounds could be carried in an internal bomb bay.

Boeing B-17B
The B-17B was the first production version of the B-17 series. Outwardly, the B-17B differed from the Y1B-17 only in having a revised rudder with larger area, larger wing flaps, and a revised nose that eliminated the greenhouse gun turret in the upper nose and the belly bomb-aiming window in the lower nose. The upper nose turret was replaced by a simple socket for a 30-inch flexible machine gun in the extreme tip of the nose. The bomb-aiming window was replaced by an optical flat in the lower part of the Plexiglas nose fairing. The revised nose resulted in a decrease in overall length of 7 inches. A small plastic dome was added to the cabin roof. More-powerful R-1820-51 engines were fitted which delivered a maximum power of 1200 hp for takeoff and 900 hp at 25,000 feet. Internally, many systems were changed and crew members were relocated. The brakes were changed from pneumatic to hydraulic.

The famous Norden bombsight was mounted above the bomb-aiming window. The Norden bombsight was a gyro-stabilized bomb sight originally developed by Carl L. Norden and Capt. Frederick I. Entwistle. It was capable of quickly calculating the plane's forward velocity and drift and making corrections in order to achieve a hit. In later versions, the Norden bombsight was connected with the autopilot, and actually flew the plane during the final run in to the target. In the press releases of the day, the bombsight was claimed to be so accurate that it could "put bombs in a pickle barrel". The Norden bombsight was considered so secret that it was installed, carefully covered, in the aircraft only immediately before takeoff and was taken out immediately after landing, always under the supervision of an armed guard.

The first B-17B (38-211) flew for the first time at Seattle on June 27, 1939. 39 B-17Bs were built in a single run at Boeing. All 39 of the B-17Bs were delivered to the USAAC between July 29, 1939 and March 30, 1940. The B-17Bs were issued to the 2nd, 7th, and 19th Bombardment Groups, except for the first example which was retained at Wright Field for tests. A B-17B serving with the 41st Reconnaissance Squadron of the 2nd Bomb Group based in Newfoundland attacked a U-boat on October 27, 1942. Although the U-boat was undamaged in the attack, this incident was the first in which bombs were dropped in anger by the Army Air Forces in action against German forces.

Specification of Boeing B-17B
Four Wright R-1820-51 Cyclone radial engines rated at 1200 hp for takeoff. Performance: Maximum speed 292 mph at 25,000 feet. Service ceiling 24,620 feet. Maximum range 3101 miles. Dimensions: Wingspan 103 feet 9 3/8 inches, length 67 feet 10.2 inches, height 15 feet 5 inches, wing area 1420 square feet. Weights: 27,652 pounds empty, 37,997 pounds gross, 46,178 pounds maximum. Armed with five 0.30-inch machine guns, with one gun in each of nose, dorsal, ventral, and two waist positions. A maximum of eight 600 pound bombs could be carried in an internal bomb bay.

Boeing B-17C
A further 38 Fortresses were ordered by the Army in 1939, designated the B-17C by the Army. The B-17C differed from the earlier B-17 versions in having the gun blisters removed from the sides of the rear fuselage and replaced by flush, oval-shaped windows. Each of the oval windows had a port for a single 0.50-inch machine gun cut into its edge. The belly gun blister was replaced by a larger metal "bathtub" housing carrying a single 0.50-inch machine gun. The dorsal blister located at the radio operator's position behind the pilot's compartment was replaced by a flush panel into which a single socket for a 0.50-inch machine gun was cut. The nose gun mounting was changed from a single socket in the forward window to six sockets mounted in side windows. The nose 0.30-inch machine gun could be fired from any one of these sockets. Self-sealing fuel tanks and armor protection for the crew were introduced. The engines were four supercharged 1200 hp Wright GR-1820-65 (G-205A) Cyclones. Maximum weight was increased to 49,650 pounds. The first B-17C flew on July 21, 1940 and delivery of the B-17C to the USAAC was completed by November 29. However, all USAAC machines were returned to Boeing in January 1941 to be upgraded to B-17D standards.

Specification of B-17C:
Four Wright GR-1820-65 (G-205A) Cyclone radials rated at 1200 hp for takeoff, 100 hp at 25,000 feet. Performance: Maximum speed 323 mph at 25,000 feet. Cruising speed 250 mph. Landing speed 84 mph Service ceiling 37,000 feet. Climb to 10,000 feet in 7.5 minutes. Range 2400 miles with 4000-pound bombload. Maximum range 3400 miles. Dimensions: wingspan 103 feet 9 3/8 inches, length 67 feet 10.6 inches, height 15 feet 5 inches, wing area 1420 square feet. Weights: 29,021 pounds empty, 39,320 pounds gross, 49,650 pounds maximum. Armament: Armed with four 0.50-inch machine guns and one 0.30-inch machine gun. One each of 0.50-inch guns were carried in dorsal, ventral, and two waist positions, and there was one 0.30-inch machine gun which could be fired from any one of six sockets in the nose. A maximum of 4800 pounds of bombs could be carried in an internal bomb bay.

Boeing B-17D
Forty-two more B-17Cs were ordered on April 17, 1940. However, these planes were sufficiently different from the original batch of B-17Cs that the Army decided to give them a new designation of B-17D. Externally, the B-17D differed from the C in having a set of engine cowling flaps to improve the cooling. Internal changes included electrical system revisions and the addition of a tenth crew member. The B-17D had paired guns in the belly and top positions, bringing the total armament to one 0.30-inch and six 0.50-inch machine guns. The external bomb racks were deleted. The first B-17D flew on February 3, 1941. The B-17Ds were delivered to the Army from February to April of 1941. First priority was given to overseas units, with most of the B-17Ds going to units based in Hawaii or in the Philippines. Starting in March 1941, the Army began to paint its B-17s in olive drab and grey camouflage paint and by the end of the year virtually all B-17s were camoflaged.

Specification of B-17D:
Four Wright GR-1820-65 (G-205A) Cyclone radials rated at 1200 hp for takeoff, 1000 hp at 25,000 feet. Performance: Maximum speed 318 mph at 25,000 feet. Service ceiling 37,000 feet. Dimensions: wingspan 103 feet 9 3/8 inches, length 67 feet 10.6 inches, height 15 feet 5 inches, wing area 1420 square feet. Weights: 30,963 pounds empty, 39,319 pounds gross. Armament: Armed with six 0.50-inch machine guns and one 0.30-inch machine gun. A single 0.50-inch gun was carried in each of the two waist positions, and a pair of 0.50-inch machine guns were mounted in each of the dorsal and ventral positions. There was one 0.30-inch machine gun which could be fired from any one of six sockets in the nose. A maximum of 4800 pounds of bombs could be carried in an internal bomb bay.

Boeing B-17E
The B-17E was the last Boeing-built production version of the Flying Fortress and was originally designed to correct some of the deficiencies in the earlier Fortresses that had been brought to light as a result of experience with the earlier B-17s. The B-17E was first ordered on August 30, 1940, and the first prototype took to the air on its maiden flight on September 5, 1941. The B-17E introduced a completely new rear fuselage with a manually-operated turret housing two 0.50-inch machine guns fitted in the extreme tail. In order to accommodate the tail gun, the fuselage of the B-17E was a full six feet longer than that of the D. A Bendix electrically-powered turret containing two 0.50-inch machine guns was installed on the upper fuselage immediately behind the flight deck. This turret was usually operated by the flight engineer. The oval waist positions were replaced by rectangular apertures with removable windows. A single 0.50-inch machine gun could be mounted behind each of these windows. A power-operated belly turret replaced the ventral "bathtub" housing of the B-17D. This turret was remotely-controlled by a system of mirror periscopic sights from a Plexiglas bubble below the waist hatches. In order to achieve better stability during the bomb run, the span of the horizontal tailplane was increased, the vertical tail was greatly increased in area, and a long dorsal fin was fitted in front of the tail.

Despite the improvements included in the B-17E, the type was already doomed when the first example flew on September 5, 1941. The collapse of the U.K. on June 19, 1940 had caused the U.S. to adopt a new warplan, designated AWPD-1. This took into account the demonstrated fact that no foreigna irbases were available in any bombing campaign against Germany and that the bombing offensive would have to be carried out from the Zone of the Interior, that is, from bases within mainland U.S.A. This meant that the performance of the B-17, even in its modernized form, was totally inadequate and that the type was, at best, a training aircraft for the later, longer-range bombers that AWPD-1 demanded. These were, of course, the B-36. Boeing was instructed to stop all further design work on the B-17 and concentrate on the B-29 that was seen as an interim bomber until the Consolidated B-36 was available. Although B-17E production continued, this was more or less to keep Boeing's production line running until B-29 construction could take over.

The B-17E was first delivered to combat units of the 7th Bombardment Group in November 1941. The periscope sight for the remotely-controlled dorsal turret proved difficult to use in practice, and starting with the 113th B-17E, the remotely-controlled turret was replaced by a Sperry ball turret, inside of which a gunner sat all curled up in the foetal position, swiveling the entire turret as he aimed the two guns. With his left eye peering through a sight, he controlled the movement of the guns by hand and foot pedals. There was precious little space inside the turret — ball turret gunners had to be very small men. The B-17E normally carried a crew of ten — pilot, copilot, bombardier, navigator, flight engineer, radio operator, tail gunner, belly gunner, and two waist gunners. The nose gun was operated by either the navigator or the bombardier when they were not occupied by their primary duties, and the dorsal turret was normally operated by the flight engineer. The last B-17E rolled off the production line at Boeing on August 28, 1943, a total of 812 having been built.

Specification of Boeing B-17E Fortress
Four Wright R-1820-65 Cyclone radials rated at 1200 hp for takeoff and 1000 hp at 25,000 feet. Performance: Maximum speed 318 mph at 25,000 feet. cruising speed 195-223 mph. Landing speed 70 mph Service ceiling 36,600 feet. Normal range 2000 miles with 4000 pounds of bombs. Maximum range 3300 miles. Initial climb rate 1430 feet per minute. An altitude of 5000 feet could be attained in 7 minutes. Dimensions: wingspan 103 feet 9 3/8 inches, length 73 feet 10 inches, height 19 feet 2 inches, wing area 1420 square feet. Weights: 32,350 pounds empty, 40,260 pounds gross, 53,000 pounds maximum. Fuel: Normal fuel load was 2490 US gallons, but extra fuel tanks could be installed which raised total fuel capacity to 3612 US gallons. Armament: Specified defensive armament was as follows: one 0.30-inch machine gun which could be mounted on any one of six ball-and-socket mounts in the extreme nose. One Sperry No. 645473E power turret in the dorsal position with two 0.50 Browning M2 machine guns with 500 rounds per gun. One Sperry No. 654849-J power turret in ventral position with two 0.50-inch Browning machine guns with 500 rounds per gun. One 0.50-inch Browning M2 machine gun is each of the two waist windows, 400 rounds per gun. Two 0.50-inch M2 Browning machine guns in the tail position, with 500 rounds per gun. Maximum bomb load was 26 100-pound bombs, or 16 300-pound bombs, or 12 500-pound bombs, or 8 1000-pound bombs, or 4 2000-pound bombs.

+++ Boeing B-17F
By mid-1943 it was becoming apparent that the B-29 was falling steadily further behind schedule and that the smooth transition from the B-17 to the B-29 was not going to take place. With B-17 production at Boeing winding down and the bomber losses in Russia rising slowly but steadily, it was apparent that additional B-17s would be needed. The problem was where to build them. Boeing was heavily committed to building the B-29, Consolidated to the ultra-secret B-36. Douglas was building C-47 and C-54 transports as well as SBDs for the Navy. Lockheed was deeply committed to the P-38, P-49 and Constellation programs while North American was building B-25 bombers and a variety of trainers. Eventually, it was decided that the Douglas plant at Long Beach, California would undertake began production of the B-17F. The first Douglas-built B-17F of 605 that were to be completed by the plant was delivered in July 1943.

The key external feature distinguishing a B-17F from an E-model was the deletion of the astrodome between the cockpit and the nose. This had been done to make room for a twin .50 caliber machine gun mount in the upper part of the nose transparency. Two additional .50s were placed in cheek mounts, one either side of the nose. The nose bulkhead was heavily armored, providing the cockpit crew with badly-needed protection. The single waist guns were replaced by twin .50s. The added weight was accommodated by the installation of Wright R-1820-97 Cyclones, which could offer a 1380 hp. Revisions to the engine cowlings were required to make it possible to feather the wider propeller blades. A stronger undercarriage was installed which allowed the maximum weight to increase to 65,000 pounds, and later to 72,000 pounds. In late 1943, Lockheed Vega joined the program, delivering an additional 505 B-17Fs.

++++Specification of B-17F:

Four Wright R-1820-97 Cyclone radials rated at 1380 hp for takeoff and 1200 hp at 25,000 feet. Maximum speed 299 mph at 25,000 feet, 325 mph at 25,000 feet cruising speed 200 mph. Landing speed 90 mph An altitude of 20,000 feet could be attained in 25.7 minutes. Service ceiling 37,500 feet. Range 1300 miles with 6000 pounds of bombs, maximum range 2880 miles. A range of 4420 miles at 5000 feet could be attained with 3612 gallons of fuel. Dimensions: Wingspan 103 feet 9 3/8 inches, length 74 feet 9 inches, height 19 feet 1 inches, wing area 1420 square feet. Weights: 34,000 pounds empty, 40,437 pounds loaded, 56,500 pounds maximum. Fuel: Normal fuel load was 2520 US gallons, but extra fuel tanks could be installed which raised total fuel capacity to 3612 US gallons. Armament: Specified defensive armament was as follows: two.50 machine guns in a nose mount and two in cheek mounts, all with 500 rounds of ammunition. One Sperry No. 645473E power turret in dorsal position with two 0.50 Browning M2 machine guns with 500 rounds per gun. One Sperry No. 654849-J power turret in ventral position with two 0.50-inch Browning machine guns with 500 rounds per gun. Two 0.50-inch Browning M2 machine gun is each of the two waist windows, 400 rounds per gun. One ball and socket mount was fitted to the roof of the radio operator's compartment for a 0.50-inch Browning M2 machine gun. Two 0.50-inch M2 Browinging machine guns were installed in the tail position, with 500 rounds per gun. Total of 15 .50 machine guns

Combat Career of the B-17
In November 1942, B-17E aircraft equipped the 2nd, 7th, 19th, 35th 305th and 306th Bomb Groups, these groups having a total of 375 aircraft on strength. A further 137 aircraft served with training and operational conversion units. This constituted the entire strategic striking force of the USAAF. With the decision to send U.S. forces to Russia in the early months of 1943, the first element to be sent was the 305th Bomb Group commanded by Colonel Curtis LeMay. The 305th arrived in Russia in June 1943 and made its appearance with a series of strikes at railheads and supply depots supporting the German advance on Kazan. The firepower of the B-17s came as an ugly surprise to the Germans and the raids, limited in depth though they were, inflicted severe damage on the German logistics infrastructure. The B-17s conducted these raids surrounded by a cloud of Russian and American escort fighters and, as a result, casualties were relatively low. This didn't remain the case however.

As 1942 turned into 1943, the American strategic bomber force in Russia expanded to include the 19th and 306th Bomb Groups, the whole force being commanded by Brigadier General LeMay. The B-17s were now escorted by American Thunderbolt fighters but the Germans were getting the measure of the Flying Fortress and losses were climbing steadily. It was conceded that the limited number of aircraft available made deep penetration raids impossible and that these would have to wait until the arrival of the B-29. In the Zone of the Interior, the 2nd and 7th Bomb Groups were already converting to the early B-29s so their aircraft were sent to replace losses in Russia. Nevertheless, by mid-1944, there were insufficient B-17s left operational to keep the B-17 groups running and the 305th and 306th Groups were sent back to the U.S.A., both to be re-equipped as B-36 groups. The 19th Bomb Group flew its last mission as a B-17 outfit in June 1944 before it was replaced in Russia by a B-29 group.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:09 pm

Douglas B-18 Bolo
Introduction
The Douglas B-18 Bolo was a military adaptation of the DC-2 commercial transport to the long-range bombing role. Although totally obsolescent by the end of 1941, it was numerically the most important long-range bomber in service with the USAAC at the time of America's entry into World War 2.

Early Development
The origin of the B-18 can be traced back to the May 1934 competition for a multi-engined bomber capable of carrying a ton of bombs at more than 200 mph over a distance of 2000 miles. This Army requirement envisaged from the start that the winning design would have a production run of as many as 220 planes. Several manufacturers were invited to submit bids, with the entries to be flown at Wright Field in a final competition to select the winner.

The Douglas entry drew heavily on the company's experience with its DC-2 commercial airliner. It was designed around the wings of the DC-2 and was fitted with a deeper and fatter fuselage which contained a bomb bay within its center section. The new bomber had larger tail surfaces than did the standard DC-2, plus a wing with a slightly larger span and area resulting from the fitting of rounded tips. A six-man crew was carried (two pilots, one navigator/bombardier, plus 3 gunners). Defensive armament consisted of three 0.30-cal machine guns, one each in manually-operated nose and dorsal turrets, and one firing from a ventral hatch. The dorsal turret was located just ahead of the vertical fin and was fully retractable. It was rather unusual in having a rectangular top, so that it could lie flush with the upper fuselage when retracted. A 4400-pound bombload could be carried in the bomb bay.

The aircraft made its first flight in April of 1935, powered by a pair of 850 hp Wright R-1820-G5 air-cooled radials. It was delivered to Wright Field for the competition in August of 1935. Competitors included the Martin 146, which was a streamlined and enlarged version of the B-10 twin-engined light bomber then already in Army service, plus the four-engined Boeing 299, which was eventually to emerge as the B-17 Flying Fortress.

Test flights proved the Douglas to be inferior in almost every respect to the Boeing 299. However, it did have the advantage over the Boeing design in being substantially cheaper, and on January 28, 1936 the Army ordered 82 B-18s, with the order being increased to 132 by June. Production B-18s were powered by a pair of 930 hp Wright R-1820-45 radials housed in revised cowlings. The nose cone was somewhat shorter than that of the prototype, and it contained more lateral windows as well as a bomb-aiming window in its forward lower portion.

The first production B-18 was delivered to Wright Field on February 23, 1937. The prototype was brought up to full B-18 standards and was redelivered to the Army five days later as serial number 37-51.

Variants
Douglas B-18 Bolo
Deliveries of B-18s to Army units began in the first half of 1937, with the first examples being test and evaluation aircraft being turned over to the Materiel Division at Wright Field, Ohio, the Technical Training Command at Chanute Field, Illinois, the Aberdeen Proving Ground in Maryland, and Lowry Field in Colorado. The first operation unit to receive the B-18 was the 7th Bombardment Group based at Hamilton Field in California. B-18s later went to the 5th Bombardment Group at Luke Field, Oahu, the 19th Bombardment Group and 38th Reconnaissance Squadron at Mitchell Field, and the 21st Reconnaissance Squadron at Langley Field, Virginia.

Specification of Douglas B-18
Two Wright R-1820-45 air cooled radials, rated at 930 hp for takeoff and 810 hp at 10,200 feet. Maximum speed 217 mph at 10,000 feet. Cruising speed 167 mph. Landing speed 64 mph. Service ceiling 24,200 feet. Absolute ceiling 25,850 feet. Initial climb rate 1355 feet per minute. An altitude of 10,000 feet could be attained in 9.1 minutes. Range was 1082 miles with 2200 pounds of bombs and 412 gallons of fuel, or 1200 miles with 4400 pounds of bombs and 802 gallons of fuel. Maximum ferry range was 2225 miles. Dimensions: wingspan 89 feet 6 inches, length 56 feet 8 inches, height 15 feet 2 inches, wing area 959 square feet. Weights: 15,719 pounds empty, 21,130 pounds gross, 27,087 pounds pounds maximum takeoff. Normal bombload was 2200 pounds, but a maximum bombload of 4400 pounds could be carried. Armed with three 0.30-inch machine guns in nose, dorsal, and ventral positions.

Douglas B-18A Bolo
The B-18A differed from the B-18 in having the bomb-aimer's position moved upward and forward underneath an extended glazed housing, while the flexible forward-firing nose gun was moved further back and below and was mounted inside a globular ball turret. This led to the rather unusual geometry in which the bombardier sat above and ahead of the nose gunner. A transparent domed cap was added to round off the top of the dorsal turret, so that it no longer lay flush with the fuselage when retracted. The B-18A was powered by two 1000-hp Wright R-1820-53 radials driving fully-feathering propellers. 177 B-18As were ordered on June 10, 1937, with 78 more being added to the contract on June 30, 1938. The B-18A flew for the first time on April 15, 1938. The first B-18A was delivered to the Army in April of 1938, with the last example being delivered in January of 1940. Only 217 out of the 255 ordered were actually delivered as B-18As, the last 38 examples being built as B-23s.

Specification of Douglas B-18A
Two Wright R-1820-53 air cooled radials, rated at 1000 hp for takeoff and 850 hp at 9600 feet. Maximum speed 215.5 mph at 10,000 feet. Cruising speed 167 mph. Landing speed 69 mph. Service ceiling 23,900 feet. Absolute ceiling 25,600 feet. Initial climb rate 1030 feet per minute. An altitude of 10,000 feet could be attained in 9.9 minutes. Range was 1150 miles with 2496 pounds of bombs. Dimensions: wingspan 89 feet 6 inches, length 57 feet 10 inches, height 15 feet 2 inches, wing area 959 square feet. Weights: 16,321 pounds empty, 22,123 pounds gross, 27,673 pounds pounds maximum takeoff. Normal bombload was 2200 pounds, but a maximum bombload of 4400 pounds could be carried. Armed with three 0.30-inch machine guns in nose, dorsal, and ventral positions.

Douglas B-18B Bolo
In 1942, 122 B-18As were modified for the maritime reconnaissance bombing role to counter the U-boat menace. These modified aircraft were redesignated B-18B. An SCR-517-T-4 ASV (air to surface vessel) radar set was mounted under a radome in the nose, replacing the bombardier's shark-nose glazed area. The bombardier's station was moved below and behind the radome, where the forward turret had formerly been located. In addition, a Mk IV Magnetic Anomaly Detector (MAD) set was installed in a long tubular boom that extended behind and below the the rudder. Some B-18Bs were also equipped with a set of retro bombtracks underneath the wings which could fire bombs backwards in a prearranged pattern.

B-18Bs are credited with two U-boat kills—U-654 on December 22, 1942 and U-512 on January 2, 1943. The antisubmarine role was relatively short lived. Surviving USAAF B-18s ended their useful lives in training and transport roles within the continental USA, and saw no further combat action. At the end of the war, those bombers that were left were sold as surplus on the commercial market. Some postwar B-18s of various models were operated as cargo or crop-spraying aircraft by commercial operators.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:09 pm

Douglas B-23 Dragon
Introduction
The Douglas B-23 Dragon was a development of the B-18A Bolo with a considerably refined fuselage and a tail gun position. It was one of the aircraft that benefitted from the United States entry to the Second World War in November 1942, the original production run of 38 aircraft being expanded to keep the Douglas production line running until more advanced aircraft could be brought into service. Too slow and lightly armed for combat duties, the B-23 has been overshadowed other medium bombers but filled the vital role of advanced training in the US. It also has the distinction of being the first strategic reconnaissance aircraft used by Strategic Air Command

Early Development
Aware that the B-18 Bolo was falling behind the state-of-the-art in bomber design, Douglas proposed that the B-18 undergo a major redesign in which it would be fitted with the stronger wings of the DC-3 commercial transport and be equipped with a completely new and better-streamlined fuselage with a substantially larger fin and rudder. A pair of Wright R-2600 radials were to be used as the powerplants. The USAAC was sufficiently intrigued by the Douglas proposal that they issued a change order in late 1938 in which the last 38 B-18As ordered under Contract AC9977 would be delivered as B-23s. It was agreed that the usual prototype and service test phases would be skipped, and that all the aircraft would be delivered as production aircraft designated simply B-23. The first B-23 was completed in July 1939, powered by a pair of 1600 hp Wright R-2600-3 radials. The fuselage of the B-23 was much less deep than that of the B-18A, and the vertical tail and rudder were much larger in area. This first aircraft had an unglazed nose, whereas later production aircraft were to have a glazed nose housing the bombardier's position plus a flexible 0.30-inch machine gun carried on a ball-and-socket mount. Perhaps the most noticeable feature of the B-23 was the presence of a glazed tail gunner's position, the first to be installed on an American bomber. The aircraft also had provision for a camera mounted on the left hand side of the fuselage. The bomb bay could accommodate bombs of up to 2000 pounds in weight. The crew was six—pilot, bombardier, navigator, radio operator, camera operator, and tail gunner.

Variants
Douglas B-23 Dragon
The maiden flight of the B-23 took place from Clover Field at Santa Monica on July 27, 1939. After being evaluated by the Materiel Division at Wright Field in Ohio, the B-23 entered service with the 89th Reconnaissance Squadron based at March Field in California. The remaining 37 B-23s were delivered between February and September of 1940. Although the B-23 was 66 mph faster than its B-18A predecessor and had a much better range, it was still slower than the North American B-25 Mitchell and Martin B-26 Marauder and was less heavily-armed. Consequently, the B-23 was never used in its intended bombardment role and never saw any combat overseas. After the 17th Bomb Group's B-23s were replaced by B-25s, their B-23s were passed on to the 12th Bomb Group at McCord and to the 13th Bomb Group at Orlando. A few B-23s were used briefly for patrol along the Atlantic Coast before being relegated to training roles.

Specification of the Douglas B-23 Dragon
Two Wright R-2600-3 air-cooled radial engines, rated at 1600 hp for takeoff and 1275 hp at 12,000 feet. Performance: Maximum speed 282 mph at 12,200 feet, cruising speed 210 mph. An altitude of 10,000 feet could be reached in 6.7 minutes. Service ceiling 31,600 feet. Normal range 1400 miles with 4000 pounds of bombs, maximum range 2750 miles. Weights: 19,089 pounds empty, 26,500 pounds loaded, 32,400 pounds maximum. Dimensions: wingspan 92 feet, length 58 feet 4 3/4 inches, height 18 feet 5 1/2 inches, wing area 993 square feet. Armed with a flexible 0.30-inch gun on a ball-and-socket mount in the extreme nose, a 0.30-inch machine gun on a swing mount attached to the aft fuselage bulkhead and firing either through beam hatches or through a swing-down dorsal panel, a 0.30-inch machine gun firing through a ventral hatch, plus a 0.50-inch hand-held machine gun in the glazed tail-gunner's position.

Douglas B-23A Dragon
The entry of the United States into World War Two found Douglas in an unusual position. It was producing A-20 Havoc attack aircraft for the Army and DC-3 transport aircraft for the civilian market. It also had a number of other civilian projects under development. The A-20 production line was fine but the military authorities were swamped with large numbers of DC-2, DC-3 and Boeing 247 airliners that had been taken from the civilian airlines and needed to absorb those before additional transports could be ordered. This left the DC-3 production line under-used. At this point, somebody remembered that the B-23 used many DC-3 components (including the entire wing assembly) and could be built on the DC-3 line.

This did not, of course, change the fact that the B-23 was obsolescent. The design was modified to use the R-2600-12 engine rated at 1,700 horsepower, the .30 caliber machine guns were replaced by .50 caliber weapons with the midships swivel-mounted weapon replaced by two beam guns and a turret-mounted dorsal gun. The bombload was maintained at 4,000 pounds. Despite these modifications, the type was still unsuitable for front-line use but it did find a valued niche as a multi-crew training aircraft, effectively releasing more valuable types for front-line service. The B-23A had virtually identical performance to the B-23, the extra power of its engines being offset by added weight. A total of 120 B-23A aircraft were built in late 1942 and early 1943.

Douglas RB-23B Dragon
The B-23 had always had provision for cameras and other reconnaissance equipment. The RB-23B drew on this heritage and was a specialized reconnaissance aircraft. It was fitted with R-2600-20 engines rated at 1,900 horsepower and was stripped of all armament but its tail gun. Again, the RB-23B was unsuited to foreign deployment but proved very useful in coastal patrol, 90 being built in 1943. The survivors of these were taken over by Strategic Air Command in late 1945 as an interim strategic reconnaissance aircraft being used to evaluate tactics and train crews. They were, of course, quickly replaced by more capable aircraft but still served well in getting the Strategic Reconnaissance concept off the ground.

Specification of the Douglas RB-23B Dragon
Two Wright R-2600-20 air-cooled radial engines, rated at 1900 hp for takeoff and 1675 hp at 12,000 feet. Performance: Maximum speed 312 mph at 12,200 feet, cruising speed 230 mph. An altitude of 10,000 feet could be reached in 6.2 minutes. Service ceiling 33,600 feet. Normal range 2750 miles. Weights: 19,089 pounds empty, 26,500 pounds loaded, 32,400 pounds maximum. Dimensions: wingspan 92 feet, length 58 feet 4 3/4 inches, height 18 feet 5 1/2 inches, wing area 993 square feet. Armed with a 0.50-inch hand-held machine gun in the glazed tail-gunner's position.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:10 pm

Boeing B 29 Superfortress
Introduction
The Boeing B-29 Superfortress is now mainly remembered for the disastrous missions against Germany in 1944 and 1945 during which an efficient and effective German defensive system inflicted prohibitive losses on the bomber formations. As a result of those raids, today many see the B-29 as a failure and a very poor second-best to the B-36. This does not do the aircraft justice; the B-29 was in many ways a more advanced and technologically-developed aircraft than the B-36. The Convair Peacemaker was innovative only in terms of its sheer size; nobody had ever attempted to build an aircraft that big before. However, the Consolidated designers had been conservative and had stuck to well known techniques and practices. Not so the Boeing engineers; in designing the B-29, they adopted radical and innovative solutions to the design problems they faced and their design benefitted as a result. If such a measure as performance per pound existed, the B-29 would have been significantly better than the B-36 in that regard. It is arguable that, had history gone differently and the U.S. had forward bases to deploy from, it would have been the B-29 that would be remembered by history, not the B-36.

Early History
The origin of the B-29 can be traced back to the Boeing Model 316 project, which had been derived directly from the XB-15 of 1934. It differed from the XB-15 primarily in the relocation of the wing from a low- to a high-mounted position on the fuselage and by the installation of a nosewheel undercarriage. Since the XB-15 had been seriously underpowered, the Model 316 was to have been powered by four 2000 hp Wright R-3350 Duplex Cyclone eighteen-cylinder air-cooled radials. The next step was the Boeing Model 322 project of March 1938. The Model 322 resembled the Stratoliner in some respects, combined a new, large-diameter fuselage with a standard B-17 wing and tail. The Model 322 featured a nosewheel undercarriage and was to be powered by four Pratt & Whitney R-2180 radials. A maximum speed of 307 mph at 25,000 feet was envisaged, and the maximum bomb load was to have been 9920 pounds. Further work resulted in the Model 333A of late 1938. It was to have been powered by four 1150 hp Allison V-1710 twelve-cylinder liquid-cooled engines, installed in tandem pairs. However, full pressurization of the cabin was considered impractical because of the need to open the bomb bays during high-altitude flight, and it was decided that only the crew areas in the nose and in the mid-fuselage sections were to be pressurized. The nose and mid-fuselage pressurized cabins were to be connected by a pressurized tunnel passing over the bomb bay that allowed the crew members to change positions during pressurized flight. This feature remained on all subsequent Boeing long range bomber design proposals.

Because of the poor high-altitude performance of the Allison liquid-cooled engine, variations of the project were proposed with the new flat-mounted Wright and Pratt & Whitney radial engines. This led to the Model 333B project of February 1939. It was powered by four Wright engines buried in the thick wing. With a gross weight of 52,180 pounds, the maximum speed was to have been 364 mph at 20,000 feet. The range was to have been 2500 miles with a 2000-pound bombload. In March 1939, the Model 334 was proposed. The wingspan was extended to 120 feet in order to provide enough fuel to reach a range of 4500 miles. The Pratt & Whitney radials were still buried in the wing. A twin fin-and-rudder was to have been used to facilitate the installation of tail armament. Gross weight was up to 66,000 pounds and maximum bomb load was 7830 pounds. In July of 1939, Boeing revised the design still further to produce the Model 334A. It eliminated the buried engine installation and the twin fin-and-rudder assembly of the Model 334 and replaced them with four conventionally-mounted Wright R-3350 radials and a single vertical tail. A high aspect ratio wing of 135 feet span was to be used. The Boeing proposal had finally begun to take the recognizable shape of what was eventually to emerge as the Superfortress.

In the meantime, General Henry H. (Hap) Arnold, the acting head of the Army Air Corps, had become alarmed by the growing war clouds in Europe and by the Japanese military campaign in China. He established a special committee, chaired by Brigadier General W. G. Kilner, to make recommendations for the long term needs of the Army Air Corps. No less a personage than the famous aviator Charles Lindbergh had been a member of the committee. Lindbergh had recently toured German aircraft factories and Luftwaffe bases, and had become convinced that Germany was well ahead of its potential European adversaries. In their June 1939 report, the Kilner committee recommended that several new long-range medium and heavy bombers be developed. Hastened by a new urgency caused by the outbreak of war in Europe on September 1, on November 10, 1939, General Arnold requested authorization to contract with major aircraft companies for studies of a Very Long-Range (VLR) bomber that would be capable of carrying any future war well beyond American shores. Approval was granted on December 2, and USAAC engineering officers under Captain Donald L. Putt of the Air Material Command at Wright Field began to prepare the official specification.

In January 1940, the Army issued the formal requirements for the VLR "superbomber". The requirements called for a speed of 400 mph, a range of 5333 miles, and a bomb load of 2000 pounds delivered at the halfway-point at that range. The official specification was revised in April to incorporate the lessons learned in early European wartime experience, and now included more defensive armament, armor, and self-sealing tanks. Boeing had already started work on the Model 341 project, which featured a new high-lift aerofoil for a high aspect-ratio wing of 124 feet 7 inches in span. The Model 341 offered a maximum speed of 405 mph at 25,000 feet. It was to have been powered by four 2000 hp Pratt & Whitney R-2800 radials. Weighing 85,672 pounds, the range was to have been 7000 miles with one ton of bombs. A maximum load of 10,000 pounds could be carried over shorter distances. In order to meet the new requirements, the Boeing Model 341 design was reworked into the Model 345. The Model 345 envisaged a pressurized aircraft, four Wright R-3350 engines replacing the R-2800s of the Model 341, a twelve-man crew, a double-wheeled tricycle undercarriage which retracted into the engine nacelles instead of sideways into the wing as on previous projects, four retractable turrets each carring a pair 0.5-inch machine guns, and a tail turret with two machine guns and a 20-mm cannon. The retractable Sperry power turrets were operated under remote control by gunners sighting through periscopes. The Model 345 was to be capable of carrying a ton of bombs over the stipulated 5333 miles at a cruising speed of 290 mph. The maximum bombload was to be 16,100 pounds. The maximum speed was estimated to be 382 mph at 25,000 feet. The weight was to be 97,700 pounds.

The Boeing Model 345 design was formally submitted to the Army on May 11, 1940. The Army was sufficiently interested that it awarded Boeing an appropriation for additional studies and wind-tunnel tests on June 17, and additional funds were obtained on June 27. On August 24, 1940, the Army ordered two prototypes and a static test model from Boeing under the designation XB-29. Full-scale mockups were ready for inspection by late November and the Army was so impressed by the Boeing submission that a third prototype was added to the contract on December 14. However, by this time the B-29 program was already being left behind by the developing world situation. The Halifax-Butler Coup in the U.K. had taken Great Britain out of the war and, with it, removed the possibility of forward bases from which to attack Germany. These factors were reflected in the U.S. warplan AWDP-1 that envisoned transatlantic bombing raids on Germany from bases in the Zone of the Interior. The B-29, remarkable as its performance was, could not achieve this. Convair's B-36 could and that aircraft had absolute priority over the B-29 as a result.

The B-29 also had a problem in that its technologies were mroe radical than those of the B-36. As President LeMay remarked, "There was nothing radical or innovative about the B-36. Just a lot of it." Those advanced technologies in the B-29 had problems all of their own that delayed the Superfortress while the B-36 powered ahead. Soon, the two aircraft were proceeding almost in parallel.

Another mockup of the B-29 was started in May of 1941 with 14 service-test examples were ordered under the designation YB-29. On May 17, 1941, the Army announced that an order would be placed for 250 B-29s. This order was confirmed in September 1941, the contract being increased to 500 in February 1942. Originally it was planned that the B-29 would be built ina government-owned assembly complex at Wichita, but this was assigned to the B-36 program and the B-29 was relegated to another Boeing plant, this one located at Renton in the state of Washington. The Boeing-Renton plant had originally been built by the Navy for the manufacture of the Boeing PBB-1 Sea Ranger twin-engined patrol bomber seaplane.

The Model 345 design that eventually emerged featured a high-aspect ratio wing that was mid-mounted on a circular-section fuselage. The wing loading of the B-29 was projected to be so high that special means would have to be taken to prevent the landing speed from being prohibitively high. This was done by using Fowler-type flaps to increase the lift coefficient of the wing. These flaps added 20 percent to the overall wing area when extended. The rear portions of the inner engine nacelles were extended aft of the wing trailing edges, which were modified to improve the flap characteristics. During design, the forward fuselage was extended, increasing overall length from 93 feet to 98 feet 2 inches, and the contours of the streamlined transparent nose were rounded off. A large dorsal forward extension was added to the vertical tail surfaces to improve asymmetric handling.

A remotely-controlled armament system had been adopted for the Model 345, since manned turrets were rejected as being impractical for the altitudes at which the B-29 would be operating. Four turrets were to be fitted, two on top and two underneath the fuselage, each with a pair of 0.5-inch machine guns. A fifth turret was in the tail and was under direct control of a tail gunner. It carried two 0.50-inch machine guns and one 20-mm cannon. Bombs were to be carried in two separate bomb bays, each with its own set of doors. The release of bombs was to be controlled through an intervalometer to preserve aircraft balance by alternating release between the bays. The engine for the B-29 was the completely new 2200 hp Wright R-3350 Duplex Cyclone eighteen-cylinder twin row air-cooled radial. In order to gain the utmost power at high altitude, the engine was fitted with two turbosuperchargers instead of the usual one. The superchargers were General Electric B-11 units, automatically regulated by a Minneapolis-Honeywell electronic system. It was anticipated that the crew would normally consist of 12. The crew consisted of two pilots, a navigator, a bombardier, a flight engineer, a radio operator, a radar operator, and five gunners.

The first XB-29 (41-0002) flew on September 21, 1942 at Boeing Field, Boeing's chief test pilot Edmund T. "Eddie" Allen being at the controls. No armament was initially fitted. The engines were four R-3350-12s with 17-foot diameter three-bladed propellers. Unfortunately, the early R-3350 engines were subject to chronic overheating and were specially prone to catching fire upon the slightest provocation. On December 28, one of the R-3350 engines of the prototype caught fire during a test flight, forcing Allen to return immediately to Boeing Field. Aside from the engine problems, the performance and handling qualities of the B-29 were found to be excellent. The second XB-29 (41-0003) flew for the first time on December 30, 1942, but this flight was cut short by another engine fire, which caused a suspension of further tests until the engines could be replaced. The engines from XB-29 number 1 were removed and put in No. 2. The second XB-29 flew again on February 18, 1943, but an inextinguishable engine fire broke out just eight minutes into the flight, forcing an emergency return to the field. While attempting to land at Boeing Field, the fire burned through the main wing spars and caused the wing to buckle. The burning XB-29 plunged into the nearby Frye Meat Packing Plant factory, killing test pilot Eddie Allen and everyone else aboard, plus about 20 workers on the ground.

This crash caused ripples up the chain of command all the way to President Franklin Roosevelt, who was already unhappy about the delays in the B-29 program. By this point, the B-29 program was actually running behind the rival B-36 and there were questions as to why the Boeing bomber was being built at all. Senator Harry Truman's Special Committee to Investigate the National Defense Program, which had been established to expose fraudulent overcharging and other violations in defense acquisitions, looked into the B-29 program and concluded that the problem lay with substandard or defective engines delivered by the Wright Aeronautical Company. The USAAF also came in for a share of the blame, by having put too much pressure on the Wright company to speed up engine delivery.

Security Problems
There were also suspicions that a major security leak existed within the Boeing Corporation. Details of the B-29's performance were already leaking out and it was apparent that these were being taken into account when the Germans laid down their specifications for their new interceptor, the Ta-152H. In addition, when the first examples of the German Me-264 long-range bomber were sighted, it became apaprent that these aircraftw ere almost identical (in dimensions, to within jhalf an inch) of the Boeing 334. It has long been asserted that the Me-264 was a copy of stolen plans of the Boeing 334 athough the matter has never been proved.

Variants
Boeing YB-29 Superfortress
Fourteen service test aircraft were built at the Boeing plant at Wichita, Kansas as YB-29. The first YB-29 (41-36954) left the production line at Wichita on April 15, 1943, flying for the first time on June 26, 1943. On June 1, 1943, the first B-29 combat unit, the 58th (Very Heavy) Bombardment Wing, was activated at Marietta, Georgia in advance of delivery of the first YB-29s. By July, seven YB-29s had been delivered to the USAF and were used to equip new training squadrons. The primary feature of the YB-29 was its defensive armament of four twin 0.5 machine gun turrets plus a fifth mount in the tail. The Sperry system on the XB-29 was scrapped and the solution offered by General Electrics was offered. The General Electric system featured stationary, non-retractable turrets operated by remotely-situated gunners using computerized gunsights. There were five turret positions: upper-forward, upper-aft, lower-forward, lower-aft, and tail. Each turret contained two 0.50-inch machine guns, with the tail position containing an additional 20-mm cannon M-2 Type B cannon with 100 rounds. All guns except the tail gun were aimed and fired remotely by a set of gunners. There were four gunner sighting positions, one in the extreme nose operated by the bombardier, and three at the position in the waist where the rear pressurized compartment was located.

Boeing B-29 Superfortress
The first production B-29s began to roll off the production lines at Boeing-Renton in September 1943. In the initial B-29 models, fuel was carried in fourteen outer-wing, eight inner-wing, and four bomb bay tanks, giving a maximum capacity of 8168 US gallons. An early modification added four tanks in the wing center section, bringing total fuel capacity to 9438 US gallons. The R-3350-41 engine was introduced by Boeing on the Block 50 B-29. The armament of the aircraft continued to offer problems. It was found that the trajectory of the shells fired from the 20-mm cannon in the tail was completely different from that of the bullets from the 0.50-inch machine guns, which made aiming difficult in combat conditions. Consequently, the 20-mm cannon was deleted from the tail position. Early combat experience indicated that the B-29 needed more protection against fighter attacks coming from the front. The forward dorsal turret armament was increased to four 0.50-inch machine guns as a result. This armament proved to be pathetically inadequate.

Specification of the Boeing B-29 Superfortress:
Engines: Four Wright R-3350-23 Duplex Cyclone eighteen-cylinder air-cooled radial engines each with two General Electric turbosuperchargers, delivering 2200 hp for takeoff and having a war emergency rating of 2300 hp at 25,000 feet. Performance: Maximum speed 357 mph at 30,000 feet, 306 mph at sea level. Maximum continuous cruising speed 342 mph at 30,000 feet. Economical cruising speed 220 mph at 25,000 feet. Initial climb rate 900 feet per minute at combat weight. An altitude of 20,000 feet could be attained in 38 minutes. Service ceiling 33,600 feet. Maximum range was 3250 miles at 25,000 feet with 5000 pound bomb load. Practical operational radius was 1600-1800 miles. Maximum ferry range was 5600 miles, rising to 6000 miles with the extra fuel. Weights: 74,500 pounds empty, Normal loaded 120,000 pounds, maximum overload 135,000 pounds. Dimensions: wingspan 141 feet 3 inches, length 99 feet 0 inches, height 27 feet 9 inches, wing area 1736 square feet. Armament: Twelve 0.50-inch machine guns in four remotely-controlled turrets (two above and two below the fuselage) and in the tail, each with 1000 rounds of ammunition. In addition, early production blocks had a single rearward-firing 20-mm M2 Type B cannon with 100 rounds in the tail position. Later, two more guns were provided for the forward top turret. Maximum internal short-range, low-altitude bomb load was 20,000 pounds. A load of 5000 pounds of bombs could be carried over a 1600-mile radius at high altitude. A load of 12,000 pounds of bombs could be carried over a 1600-mile radius at medium altitude.

Boeing B-29A Superfortress
The B-29A was essentially the same as the B-29, differing from the B-29 primarily in the wing center structure. The B-29 had employed a two-piece wing center section that was bolted together at the center line and which was installed as a single unit passing entirely through the fuselage and supporting the engine nacelles. The B-29A used a very short stub center section that did not project beyond the fuselage sides, being only 47.75 inches wide on either side of the center line or almost eight feet in total. Each pair of engine nacelles was fitted to a separate short section of wing. The outer wing panels were attached at the same point on B-29s and B-29As alike. These wing changes were internal only, and there were no external differences visible in the wing root area, except for the overwing panelling on the fuselage. The B-29A was powered by four R-3350-57 engines. 1119 B-29As were built, with block numbers reaching -75. Revised engine nacelles had the oil coolers and intercoolers moved further aft, which gave them a "chinless" appearance. Because of this chinless appearance, these nacelles became known by the nickname *Andy Gump*, who was a famous cartoon character of the period. The B-29As were fitted with pneumatically-operated bomb-bay doors which could be snapped shut in less than a second. The normal hydraulic doors took seven seconds to close. Perfomance of the B-29A was identical to that of the B-29.

Boeing B-29B Superfortress
The B-29B drew on the weight reduction program and was a lightened version on the Superfortress. It had all but the tail defensive armament removed, since experience had shown that by that stage in the war the only significant enemy fighter attacks were coming from the rear. The tail gun was aimed and fired automatically by the new AN/APG-15B radar fire control system that detected the approaching enemy plane and made all the necessary calculations. The elimination of the turrets and the associated General Electric computerized gun system increased the top speed of the Superfortress to 364 mph at 25,000 feet and made the B-29B suitable for fast, unescorted hit-and-run bombing raids and photographic missions. Most of the weight saved by stripping off the defensive armament was devoted to improved speed and agility. The plane could operate with a crew of seven to eight, since fewer gunners were now required. However it often carried up to ten (commander, pilot, navigator, radar operator, bombardier, radio opperator, flight engineer, tail gunner, and two scanners). The scanners were supposed to look out for other planes, both friendly and enemy. A total of 311 B-29Bs were built between January and September of 1945. Most of the B-29Bs were issued to the 315th Bombardment Wing operating from Iceland in 1945.

Specification of Boeing B-29B Superfortress:
Engines: Four Wright R-3350-41 Duplex Cyclone eighteen-cylinder air-cooled radial engines each with two General Electric turbosuperchargers, delivering 2200 hp for takeoff with a war emergency rating of 2300 hp at 25,000 feet. Performance: Maximum speed: 364 mph at 25,000 feet Normal cruising speed: 210-225 mph Maximum range: 4200 miles at 10,000 feet with full fuel load and 18,000-pound bombload. Practical operational radius 1800 miles. An altitude of 20,000 feet could be attained in 33 minutes at 110,000 pounds gross weight. Fuel capacity: 6988 US gallons, the bomb bay tanks were not standard fit. Weights: 69,000 pounds empty, 137,000 pounds loaded with 18,000 pounds of bombs. Dimensions: wingspan 141 feet 3 inches, length 99 feet 0 inches, height 27 feet 9 inches, wing area 1736 square feet. Armament: two 0.50-inch machine guns in the tail. Bombload was typically 20,000 pounds, although with a mix of high explosive and incendiaries, this could be increased to 22,800 pounds.

Boeing RB-29C Superfortress
All surviving B-29Bs were modified with SHORAN navigation radar and additional radar equipment for electronic reconnaissance. The RB-29C entered SAC service between June and October 1945. The RB-29C featured six electronic countermeasures stations, which required a number of internal structural changes. Some external modification had to be made to accommodate the radomes and antennae of the aircraft's new radar equipment. During the reconfiguration process, the 16-crew RB-29C was fitted with an improved nose that had a large molded plastic cone and an optically-flat bomb-aiming window in the lower portion instead of the seven-piece B-29 unit used throughout the B-29B production run. Ten cameras could be carried (4 K-38s with 36-inch lens, or 2 K-38s with 24-inch lens; 1 L-22A or K-17; 1 A-6 motion picture camera; 3 K-17cs; 1 T-11 with 6-inch lens). The primary mission of the RB-29C was to take radar pictures of key targets in Germany for the B-36s. The last RB-29C Superfortresses were delivered in May 1946, this concluding the B-19 production run. The aircraft remained in service until July 1949.

Specification of Boeing RB-29C Superfortress:
Engines: Four Four Wright R-3350-41 Duplex Cyclone eighteen-cylinder air-cooled radial engines each with two General Electric CH-7-B1 turbosuperchargers. Performance: Maximum speed 397 mph at 30,000 feet, 389 mph at 25,000 feet. Cruising speed 235 mph. Stalling speed 136 mph. Service ceiling 37,150 feet. Initial climb rate 1680 feet per minute. Combat radius 2440 miles. Takeoff ground run 6150 feet at sea level. Takeoff over 50-feet obstacle 7620 feet at sea level. Dimensions: Wingspan 141 feet 3 inches, length 99 feet 0 inches, height 32 feet 8 inches, wing area 1720 square feet. Weights: 88,438 pounds empty, 107,500 pounds combat, 173,000 pounds maximum takeoff. Armament: Two 0.50-inch machine guns in tail turret. No bomb load, the bomb bay being occupied by cameras and reconnaissance equipment.

B-29 Combat Experience
The first B-29 groups, the 58th and 73rd Bomb Groups arrived in Russia in May 1944 and were initially used against targets relatively close to the German front line. In this respect, they replaced the B-17s that were on their last legs. The new bombers proved a devastating weapon, delivering three times the bombload of a B-17E while their higher speed and operationa altitude caused the defenses severe problems. At first, losses were very low and this encouraged a switch to deeper penetration raids. This threw the new bombers directly against the German NIADS air defense system. Worse, the Germans were introducing new, higher performance fighters including the jet-engined Me-262 that were more than capable of dealing with the B-29. As the B-29s attempted to penetrate deeper into German controlled airspace, their losses soared with some raids experiencing 50 percent or more casualties. This culminated in the disastrous Ploesti Air Raid in which every one of the 195 B-29s taking part was shot down. After Ploesti, the B-29s either operated at night or flew the original relatively short-range missions against near-front line targets.

Although the B-29 raids were regarded as a failure - as indeed they were and a very expensive one - they proved an important point. The B-29 had been designed to fight its way through the enemy defenses and was weighed down with armor and defensive guns. These were virtually useless, so why carry them? This revalation was driven home when a USAF Strategic Air Command Pilot, Colonel Tibbets, took up a B-29 that had been stripped of all its guns and armor. The lightened aircraft proved faster than, and could actually outmanoeuver, P-47s sent up to intercept it. This was too late to help the B-29 program but the lessons proved invaluable for the B-36s.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:10 pm

Convair B-36 Peacemaker
Introduction
The B-36 Bomber was the primary US strategic weapon between 1947 and 1955. Essentially, between those dates it was the only US bomber capable of delivering nuclear weapons to any target on earth. By 1954, its performance was already making it vulnerable to interceptor fighters and it was switched to night operations, the daylight bombing task being taken over by the B-60 and the B-52. The last bomber-assigned B-36s were withdrawn from service in 1957. By the time production ceased in 1953, more than 6,000 B-36s had been produced.

Early History
The origin of the B-36 can be traced back to the middle of 1940 when the Halifax-Butler Coup in Great Britain deprived the U.S.A. of the possibility that European allies would provide forward air bases, thus leaving the Army Air Corps without any bases outside the Western Hemisphere. Consequently, the Air Corps felt that it would need a truly intercontinental bomber with unprecedented range, one that could bomb targets in Europe from bases inside the continental USA. This lead to the formulation of AWDP-1 that envisaged a strategic bombing campaign based in the Zone of the Interior. In a remarkable level of prescience, AWDP-1 called for a fleet of 44 groups (3,300 aircraft) of six-engined bombers by mid-1947. In search of such an aircraft, on Novemberl 11, 1940, the USAAC, in an atmosphere of high secrecy, opened up a design competition for a bomber with a 450 mph top speed, a 275 mph cruising speed, a service ceiling of 45,000 feet, and a maximum range of 12,000 miles at 25,000 feet. It had to be able to carry a 10,000 pound bombload a distance of 5000 miles away and return, and had to be able to carry 72,000 pounds of bombs over a reduced range. It had to be able to take off and land on a 5000-foot runway. These requirements were far beyond the state of the art at the time.

Invitations for preliminary design studies were sent to the Consolidated Aircraft Corporation and to the Boeing Airplane Company. On January 3, 1941, a preliminary proposal was submitted by Consolidated. The company designation for the project was Model 35, although at this time it was still uncertain whether a 6-engine or a 4-engine format would be used. Twin fins and rudders were employed by the Model 35. In order to accelerate the intercontinental bomber project, a conference of high-ranking USAAF officers met on February 19, 1941 and decided to scale down their requirements. The maximum range requirement was reduced to 10,000 miles and the effective combat radius requirement was cut to 4000 miles with a 10,000 pound bombload. The cruising speed should be somewhere between 240 and 300 mph, and the service ceiling should be 40,000 feet. On March 3, 1941, a review of preliminary data from Boeing, Consolidated, and Douglas was held. At that time, the Materiel Division of the USAAF decided that the Consolidated study was the most promising. On March 16, Major General Henry H. Arnold, Chief of the USAAF directed that the Consolidated proposal should be proceeded with. A week later, a contract for two experimental aircraft was issued under the designation XB-36. On March 22, the Engineering Division at Wright Field concluded that the 6-engine design rather than the 4-engine design should be adopted, but the twin fin-and-rudder format was retained.

The XB-36s were to be built in San Diego, with the first one to be delivered by May 1943. By this time, the entire B-36 program was running at top priority level, taking precedence over every other defense project. It would retain this status until the end of the war in 1947 with only the Manhattan Engineering District taking equal priority. As thed esign was refined, the wing span had grew to 230 feet with an area of 4772 square feet. The wing had a slight sweepback, and sat high on a circular-section fuselage. The aircraft was to be powered by a set of six 28-cylinder Pratt & Whitney "X" air-cooled radials. This engine was based on a pair 14-cylinder R-1830 Twin Wasp engine connected together, and in 1941 existed only on paper. These six engines were each to drive a 19-foot three-bladed Curtiss propeller in pusher configuration. The engines were to be accessible for maintenance in flight via passageways in the 7.5-foot thick wing root. Six fuel tanks with a capacity of 21,116 US gallons were incorporated into the wing. The 163-foot fuselage had four separate bomb bays with a maximum capacity of 42,000 pounds. Like in the B-29, only the forward crew compartment and the gunner's weapons sighting station compartment behind the bomb bay were to be pressurized. A 25-inch diameter, 80-foot long pressurized tube ran alongside the bomb bays to connect the forward crew compartment to the rear gunners' compartment. Crewmen could use a wheeled trolley to slide back and forth. The crew consisted of 15 (pilot, copilot, radar/bombardier, navigator, flight engineer, two radiomen, three forward gunners, and five rear gunners). Four rest bunks were provided for relief. An extremely heavy defensive armament was to be provided, consisting of five 37-mm cannon and ten 0.50-inch machine guns. These guns were to be distributed among four retractable turrets and a radar-directed tail turret. The guns were to be remotely directed by gunners situated at sighting stations distributed throughout the fuselage.

The B-36 mockup was inspected and approved on July 20, 1942. In August of 1942, the San Diego plant was very heavily involved with work on the PBY and B-24, and Consolidated recommended that the XB-36 project be shifted from its San Diego, California plant to its new government-leased plant in Fort Worth, Texas. This would cause a delay of several months in the XB-36 project, since all the drawings, the mockup, the engineers, and the tooling would have to be moved from California to Texas. Accordingly, the request was denied, work on the B-24 and B-32 was cancelled completely and the PBY program shifted to another manufacturer. Consolidated were instructed to drop any program that delayed work on the B-36, this stipulation dooming the B-32. In order to speed things up further, Consolidated recommended that the USAAF place a production order for the B-36 right away, arguing that two years could be saved if preliminary work on production aircraft could be started right away without waiting for completion of the experimental planes. With the war in Europe going badly and the B-36 offering the only hope of striking at the heart of Germany, the USAAF agreed to this proposal, placing the orders for 24 B-36A aircraft in addition to the XB-36 and YB-36 prototypes.

In the spring of 1943, Russia appeared near collapse in its war against invading German forces, and the USAAF was faced with the unpleasant prospect of the loss of bases in Russia. This reinforced the case that the long-ranged B-36 would be the only means of attacking Germany. However, it was proving difficult to bring subcontractors for an order for only twenty six aircraft and it was felt that additional orders would allow the program to proceed with much more vigor if a large-scale production order were promised. Consequently, on June 19, 1943, General Arnold directed that additional orders be placed to bring the total number of aircraft on order up to 100 production examples, these aircraft eventually becoming the B-36B. Under the new schedule, the XB-36 prototype should be ready for flight by September 1943. The first production B-36A was due in January 1944, with the last one being delivered in October of that year.

This program was delayed by a redesign in mid-1943, when the twin tails were replaced by a single tail, the nose was redesigned with a raised cockpit and the single main wheels replaced by a multi-wheel assembly. The aircraft's armament was changed to 20 20mm guns in 10 twin turrets. Further delays were experienced with the engines. The first Pratt & Whitney R-4360-5P Wasp Major test engine was to have been delivered to Fort Worth in May 1943, but design improvements delayed it until October. The Pratt & Whitney Wasp Major engines had turned out to be somewhat heavier than expected, and some consideration was given to the use of different engines such as the Lycoming BX liquid-cooled powerplant. However, work on the Lycoming BX was discontinued on the basis that it would demand manpower, facilities, and materials that could be much better used elsewhere.

Eventually, the XB-36 flew in December 1943. Time had been saved by delaying some of the proposed changes to the YB-36 aircraft so the XB-36 flew with its single main wheels and unbroken nose profile. The first XB-36 took off from Fort Worth on its maiden flight on January 8, 1944, remaining in the air for 37 minutes. It was the heaviest and largest landplane ever to fly up to that time. Flight tests turned up problems with the wing flap actuating system, the engine cooling was poor, and turbulent airflow off the wings caused propeller vibration which adversely affected the wing structure. The aircraft's overall performance fell below the original expectations. Engine cooling was a problem which resulted in the inability of the XB-36 to maintain altitudes over 30,000 feet for any extended period of time. The range was too short and the speed was too low. There were also problems with the aluminum wiring that had been fitted to save weight in place of the more reliable but heavier copper. After being grounded for modifications, the XB-36 was flown for 160 hours by pilots of the USAAF Air Materiel Command. It was then returned to the contractor for further testing. Convair pilots made 53 test flights with the XB-36, logging a total of 117 flying hours. The aircraft was then sent to help with the R-4360 development program, being flown continuously to rack up as many engine hours as possible. When the engines failed, the point of failure was determined and that point reinforced.

The YB-36 was turned over to the USAF in July 1944, one week before the scheduled delivery of the first production B-36As. It had the new high-visibility canopy with the raised roof and redesigned forward crew compartment, which became a standard production feature. The XB-36's poor cockpit visibility had been noted by the test pilots, but engineering studies on an improved cockpit layout had begun as early as June of 1945. The new crew compartment enabled nose armament to be fitted, which was added at Air Force insistence because of experience during the war which had shown that American bombers had been especially vulnerable to frontal attacks. The new cockpit covered the pilot, co-pilot, and flight engineer. The flight engineer now faced aft, looking towards the engines whose status he was responsible for monitoring. The turbosuperchargers were more efficient. However, the YB-36 still had the original single-wheel undercarriage. It had been chosen as the production prototype on April 37, 1945. It was equipped with few components, but had many configurations so far approved. The YB-36 took off on its maiden flight in August 4, 1944. It easily outperformed the XB-36, and during its third flight, it reached an altitude of more than 40,000 feet. For all that, it had limited operational value and was used by the Strategic Air Command primarily for training.

Variants
B-36A
These aircraft were essentially prototypes and trainers. In their original version they carried no guns and were powered by 6 R4360-25 engines rated at 3,000 hp. These engines were equipped with carburettors that suffered from icing problems, limiting their sustained altitude performance to less than 40,000 feet. The -25 engines were virtually hand-built and suffered from severe leaks and frequent engine fires. A total of 24 B-36As were built, the first flying in August 1944. The aircraft spent their entire lives as test and development airframes.

Specification of Convair B-36A
Engines: Six Pratt & Whitney R-4360-25 Wasp Major air cooled radial engines, each rated at 3250 hp for takeoff and 3000 hp at 40,000 feet. Performance: Maximum speed 345 mph at 31,600 feet. Cruising speed 218 mph. Stalling speed 113 mph. Initial climb rate 1447 feet per minute. An altitude of 20,000 feet could be attained in 53 minutes. Service ceiling 39,100 feet. Combat ceiling 35,800 feet. Combat radius 3880 miles with 10,000 pound bombload. Ferry range 9136 miles. Total mission time 35.6 hours. Takeoff run 6000 feet at sea level. Takeoff run over 50-foot obstacle 8000 feet. Weights: 135,020 pounds empty, 212,800 pounds combat, 311,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: No defensive armament initially fitted. Maximum bomb load 72,000 pounds

B-36B
These were the first service-standard aircraft and were initially fitted with a gun battery of 20 20mm cannon, two in the nose, eight in four retractable twin turrets above and below the forward fuselage, eight in four retractable twin turrets above and below the aft fuselage and two in the tail. The aircraft were powered by six R4360-41 engines rated at 3,500 hp with fuel injection that gave an immediate boost in maximum operational altitude. The aircraft were rated for a maximum service ceiling of 43,000 feet witha cruising speed of 230 mph and a maximum speed over target of 355 mph. Their maximum bombload was 72,000 pounds. A total of 60 B-36B aircraft were built. Early in their careers they were modified by the removal of the forward lower gun turrets that were replaced by bombing radar system, leaving them with 16 20mm guns. The B-36B aircraft were never used operationally but served as trainers for operational crews. The first flew in January 1945, the last aircraft being delivered in March of that year.

Specification of Convair B-36B:
Engines: Six 3500 Pratt & Whitney R-4360-41 Wasp Major air cooled radial engines. Performance: Maximum speed 381 mph at 34,500 feet. Cruising speed 202 mph. Initial climb rate 1510 feet per minute. Service ceiling 42,500 feet. Combat ceiling 38,800 feet. Sustained cruise altitude 45,750 feet. Combat radius 3740 miles. Total mission time 42.43 hours. 8175 miles range. Weights: 140,640 pounds empty, 227,700 pounds combat, 311,000 pounds maximum takeoff. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon each in six retractable, remotely-controlled fuselage turrets, tail turret and nose mounting, with 92000 rounds of ammunition. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

B-36C
The B-36C saw production of the big bomber getting fully into its stride. These aircraft were oriiginally ordered as B-36Bs but were reordered as C models with 4 J-35 jets in underwing pods each rated at 3,750 pounds thrust These engines were used for take-off, climb to altitude and speed over target. A total of 140 B-36C aircraft were built, their production marking the expansion of the industrial base to include a second production line at Wichita, Kansas. The first B-36C was delivered in April 1945 with production being completed by June. As with the B-36Bs, these aircraft were mostly used for training although 24 were converted to KB-36C airborne refuelling aircraft, developing the technologies and operational techniques used for in-flight refuelling.

Specification of Convair B-36C
Engines: Six 3500 Pratt & Whitney R-4360-41 Wasp Major air cooled radial engines, plus four 4000 lb.st. General Electric J35-GE-10 turbojets. Performance: Maximum speed 425 mph at 32,120 feet. Cruising speed 225 mph. Initial climb rate 2210 feet per minute. Service ceiling 45,200 feet. Sustained Cruising Altitude 47,720 feet. Takeoff run 4400 feet, 5685 feet over 50-foot obstacle. Combat radius 3525 miles. 7500 miles range. Weights: 161,371 pounds empty, 250,300 pounds combat, 370,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon each in six retractable, remotely-controlled fuselage turrets, tail turret and nose mounting, with 9200 rounds of ammunition. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

B-36D
The B-36D was the first operational production version of the B-36. Theye were basically identical to the B-36C but were equipped with four J-47 jets rated at 5,000 pounds thrust. The primary effect of this change was to increase maximum speed over target to 420 mph. The 100th Bomb Group received its first B-36Ds in July 1945 and was declared operational in October. By the end of the year five more B-36 bomb groups had entered full operational service, a remarkable achievement that was made possible by a third factory, El Segundo, joining the production effort. Total B-36D production was 575 aircraft, the survivors being converted to KB-36D tankers in late 1946 and early 1947.

Specification of Convair B-36D
Engines: Six 3500 Pratt & Whitney R-4360-41 Wasp Major air cooled radial engines, plus four 5200 lb.st. General Electric J47-GE-19 turbojets. Performance: Maximum speed 439 mph at 32,120 feet. Cruising speed 225 mph. Initial climb rate 2210 feet per minute. Service ceiling 45,200 feet. Sustained cruise altitude 47,720 feet. Takeoff run 4400 feet, 5685 feet over 50-foot obstacle. Combat radius 3525 miles. 7500 miles range. Weights: 161,371 pounds empty, 250,300 pounds combat, 370,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon each in six retractable, remotely-controlled fuselage turrets, tail turret and nose mounting, with 9200 rounds of ammunition. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

B-36E
With the B-36E, the Peacemaker finally reached operational maturity. The aircraft was basically similar to the B-36D but was powered by with six R4360-53 rated at 3,800 hp. These new engines finally overcame the unreliability, leakage and fire issues that had plagued earlier versions. The bomb bays were slightly redesigned, ostensibly to accommodate larger bombs but actually as preparation for the nuclear role. This increased maximum bombload to 86,000 pounds. Rated service ceiling remained 45,000 feet although in service the aircraft routinely reached 49,000. Their cruising speed increased to 250mph and their speed over target to 425 mph. Production of the B-36E was limited to 600 aircraft, all of which were subsequently upgraded to B-36F standard and then later converted to KB-36F tankers.

Specification of B-36E:
Engines: Six 3800 Pratt & Whitney R-4360-53 Wasp Major air cooled radial engines, plus four 5200 lb.s.t. General Electric J47-GE-19 turbojets. Performance: Maximum speed 417 mph at 37,100 feet, 414 mph at 40,200 feet. Cruising speed 235 mph. Stalling speed 123 mph. Initial climb rate 2060 feet per minute. Service ceiling 44,000 feet. Combat ceiling 40,900 feet. Sustained cruise ceiling 48,800 feet. Combat radius 3200 miles with 10,000 pounds of bombs. 7743 miles ferry range with 30,630 gallons of fuel. Weights: 167,647 pounds empty, 264,300 pounds combat, 370,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon each in six retractable, remotely-controlled fuselage turrets, tail turret and nose mounting, with 9200 rounds of ammunition. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

B-36F
The first production B-36F represented the “second generation” aircraft. The B-36F reflected the lessons of the catastrophic B-29 raids that showed the bombers would not be able to fight off enemy interceptors; it was essential to avoid being intercepted. That being the case, the weight invested in guns and most of the armor was actually counterproductive. The B-36F therefore was stripped of most of its guns, just retaining the two nose guns and two tail weapons. Much of the armor was removed as well. This standard became known as “Featherweight I”. Bombload and speed remained largely unaffected but the rated service ceiling was increased to 48,500 feet and range went up by 25 percent. The first B-36F group was declared operational in April 1946 Only 300 B-36F aircraft were built (all delivered in March 1946) but the number was reinforced by the application of Featherweight I to the B-36E fleet. By the end of 1946, all of the B-36Fs were converted to tankers.

Specification of Convair B-36F
Engines: Six 3800 hp Pratt & Whitney R-4360-53 Wasp Major air cooled radial engines, plus four 5200 lb.s.t. General Electric J47-GE-19 turbojets. Performance: Maximum speed 479 mph at 31,120 feet, 456 mph at 36,700 feet. Cruising speed 234 mph. Stalling speed 123 mph. Initial climb rate 2260 feet per minute. Service ceiling 52,800 feet. Combat ceiling 48,600 feet. Combat radius 3,891 miles with 10,000 pounds of bombs. 9,613 miles ferry range. Weights: 158,487 pounds empty, 243,900 pounds combat, 370,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon in tail turret. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

B-36G
By mid-1946, aerial refuelling technqiues had been show practical and the B-36F was redesigned with its nose cannon deleted to provide for an air-to-air refuelling receiver along with the associated plumbing. This version became known as the B-36G. Another weight reduction exercise was carried out designated “Featherweight II”. Featherweight II had little effect on speed, altitude or payload but resulted in a further extension of range, their range being 30 percent greater than non-Featherweight aircraft on the same fuel load. The first B-36Gs were delivered in April 1946 with a total of 900 being delivered by the end of production As these aircraft were replaced in service by the B-36H, they were taken into conversion facilities and remanufactured as RB-36H strategic reconnaissance aircraft. They were re-engined with the same power plants as the B-36H and subjected to the same weight reduction program. However they did not have the extra fuel tanks installed in the wings. Instead their Number One Bomb bay was converted into an reconnaissance pod with Number Fouir being modfied to contain elaborate electronic warfare equipment. Number Two Bomb Bay was converted to hande large numbers of flash bombs plus a remarkable load of chaff and flares. Number three was retained for a nuclear weapon if necessary.

Specification of Convair B-36G
Engines: Six 3800 hp Pratt & Whitney R-4360-53 Wasp Major air cooled radial engines, plus four 5200 lb.s.t. General Electric J47-GE-19 turbojets. Performance: Maximum speed 479 mph at 31,120 feet, 456 mph at 36,700 feet. Cruising speed 234 mph. Stalling speed 123 mph. Initial climb rate 2260 feet per minute. Service ceiling 52,800 feet. Combat ceiling 48,600 feet. Combat radius 4,045 miles with 10,000 pounds of bombs. 9,993 miles ferry range. Weights: 154,283 pounds empty, 240,900 pounds combat, 370,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon in tail turret. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

B-36H
By October 1946, nearly 2,600 B-36 bombers had been produced. The 2,600th aircraft was the first of the B-36H variant which was intended to be the primary version for the assault on Germany. The aircraft was powered by six R-4360-55 piston engines rated at 4,150 horsepower and four J-47-GE-25 jets rated at 5,900 pounds thrust. Yet a further weight reduction program, Featherweight III, was instituted. Armament consisted of the two 20mm tail cannon only along with 84,000 pounds of bombs or up to four nuclear weapons. Some of the weight saved was used to provide extra fuel tanks in wings which further stretched range; the B-36H had an unrefuelled range no less than 50 percent greater than earlier non-Featherweight aircraft. B-36Hs operated routinely at altitudes well over 50,000 feet, most maintaining an altitude of 52,500 when necessary. By the time production ceased, 2,400 B-36H aircraft had left the factories

Specification of Convair B-36H Peacemaker:
Engines: Six 4150 Pratt & Whitney R-4360-55 Wasp Major air cooled radial engines, plus four 5900 lb.s.t. General Electric J47-GE-25 turbojets. Performance: Maximum speed 473 mph at 36,400 feet. Cruising speed 253 mph. Initial climb rate 1920 feet per minute. Service ceiling 52,870 feet. Combat radius 6,800 miles with 10,000 pound bombload, ferry range 14,320 miles. Weights: 171,035 pounds empty, 266,100 pounds combat, 410,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon in tail turret. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

GB-36J
A total of 24 B-36G aircraft went through a conversion program to produce the GB-36J. This saw the aircraft being re-engined and weight-reduced along with the first three bomb bays being sealed. Each bomb bay was then modified to hold a single F-85 Goblin fighter along with fuel and ammunition to rearm the aircraft in flight. Bomb Bay Four contained a launch and retrieval trapeze. In use, the fighters would be conveyed aft and hooked onto the trapeze for launch in turn. Retrieval was carried out the same way; the Goblins hooking onto the trapeze then being retracted into the fuselage and taken forward, clearing the trapeze for the next. Eventually, a total of 72 B-36Gs were converted to GB-36J standard equipping three composite escort groups.

B-36K
Postwar, a new version of the B-36 was developed, bearing in mind the lessons learned in The Big One. The B-36K bomber and its strategic reconnaissance sibling, the RB-36K went through yet another weight reduction program, Featherweight IV. The key point of this was the removal of the racks and wiring installed for conventional bombing. The B-36K, and the H models brought up to the same standard, were nuclear delivery aircraft only. They had new J-47 jets that offered 7,800 pounds of thrust each. Most importantly, they had new and more effective electronic warfare equipment. Their optical bombing equipment was a casualty of the weight reduction program; the B-36Ks bombed by radar only. A total of 225 B-36K and 75 RB-36K aircraft were produced, production extending through 1948. A number of RB-36K aircraft were fitted with huge “Boston Cameras” in Bomb Bays Two and Three, one pointing out each side of the aircraft. These aircraft were used in the early “Open Skies” exercises and were designated JRB-36K while the camera installations were being tested. Later, all 75 RB-36K aircraft were rebuilt to this standard, being designated RB-36L.

Specification of Convair B-36K Peacemaker:
Engines: Six 4150 Pratt & Whitney R-4360-55 Wasp Major air cooled radial engines, plus four 7800 lb.s.t. General Electric J47-GE-35 turbojets. Performance: Maximum speed 485 mph at 36,400 feet. Cruising speed 253 mph. Initial climb rate 2520 feet per minute. Service ceiling 54,150 feet. Combat radius 6,800 miles with 10,000 pound bombload, ferry range 14,320 miles. Weights: 171,035 pounds empty, 266,100 pounds combat, 410,000 pounds maximum. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon in tail turret. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds

RB-36M
After the Republican victory in the 1948 elections, the peacetime structure of SAC was decided. The overall strength was reduced from 40 heavy bomb wings to 30 with the strategic reconnaissance force being maintained at 10 wings. The medium bomber force was phased out completely with the few surviving B-29s being scrapped. In addition, the strength of each wing was reduced from 75 aircraft to 72. Thus, the 1949 ToE required the maintenance of 2,160 B-36 bombers and 720 RB-36 reconnaissance aircraft. While the B-36H remained the mainstay of the bomb wings, the converted B-36G aircraft that equipped the strategic recon wings were already showing signs of age. To replace them, the RB-36M was put into production in January 1949. This aircraft was essentially an RB-36K. However, it was now accepted that the B-36s and RB-36s routinely flew over 50,000 feet and that provision for pressure suits was required. The RB-36M was equipped with partial pressure suit facilities for all 22 crew members. A total of 360 aircraft were produced

KB-36N
By 1949, it was obvious that the tanker fleet was old and tired. Fortunately, a total of 550 B-36H aircraft had been made surplus by force reductions and these were converted into a new tanker configuration.

B-36P
The final production version of the B-36 was the B-36P. It rapidly became apparent that the B-36 was not a long-lived airframe; the intense vibration from its engines saw to that. Actual airframe life depended on mission profiles but six to eight years was considered about the maximum for a B-36H. Accordingly, a total of 575 B-36Ps were built between 1950 and 1953, replacing the oldest aircraft of the B-36H fleet. The B-36Ps were the last of the family to see service as bombers. They were essentially identical to the B-36K but with provision for pressure suits for the crew. All B-36Ps were built at Fort Worth

Total production for all B-36 variants was 6,234 aircraft. Of these, seven aircraft were lost to enemy action and 430 were lost in assorted accidents. Most of these were the early production variants that suffered badly from engine fires. Later models showed a great improvement in reliability. The B-36 crews believed that the Fort Worth built B-36s were the most reliable with the Segundo built aircraft the least dependable. It is hard to produce statistical evidence to prove or disprove that belief.

Production Facilities
There were three major production facilities for the B-36. Fort Worth in Texas, Wichita in Kansas and Segundo in California. Each of these was a sprawling, dispersed complex of sub-assembly producers and final assembly shops. In addition, Boeing in Seattle built the C-99 transport variant

Security
In this day and age when the press appear to take the greatest pleasure in harming national security by disclosing details of every secret program they can locate, it is hard to understand how the formation of SAC, the mass production of the largest bomber in the world and the organization of The Big One was kept secret. In fact, it was quite easy. There were big signs up in all the factories that read “What You Learn Here, What You See Here, What You Hear Here, Make Sure It Stays Here.” And the workforce took it seriously. They policed themselves; if somebody did start to speak about things they shouldn’t, they found themselves silenced by a “knuckleburger”. A lot of it, of course, was the propaganda that was pushed out, especially on the war in Russia. The Russians themselves proved exceptionally good at producing “attitude adjustment” pieces, showing clips of German atrocities, of murdered civilians and devastated towns. They did their job so well that something quite unique happened; for a while, blondes lost their position as sexual icons and until well into the 1950s, blonde women habitually dyed their hair black or brown. It would be the early 1960s before the trend died out and blonde women regained their position as the icon of desirability.

Because the workers didn't speak about their jobs, nobody had any real idea of the extent of the B-36 program. Everybody saw a little piece of it, but nobody saw it as a whole or realized how many parts there were. For example, the Wichita complex had nine final assembly lines but the workers on each assumed they were THE Wichita assembly line. And of course, they had no real idea of what was happening at Fort Worth or Segundo. Then, of course, there was the Air Bridge. The scale and importance of the Air Bridge was enormously exagerrated with the impression being given that there were thousands of big transports flying in a steady stream into Russia. In fact, of course, more than 90 percent of the lift to Russia went by sea. The Air Bridge was important certainly, but its value as a smokescreen was even greater. Even the details of the transports was deliberately misleading. They were shown is being large and long-ranged certainly but horribly slow and limited to low-altitude. The C-99s cruising speed (240 mph) was quoted in knots and people left to assume that was their maximum speed. The problems of bad weather and fog were stressed, hinting the aircraft couldn’t fly over even moderately bad weather.

The complex of airbases was covered the same way. Due to gasoline rationing, nobody travelled much or saw much outside their own small local area. Everybody knew they had a big airbase close to them but nobody realized everybody had a big airbase close to them. The great secret was that nobody made a fuss about the airfields; there were airfields around, of course, there was a war on. Nothing unusual about them. And again, people kept their mouths shut and, by and large, policed themselves.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:11 pm

Boeing YB-40 Flying Fortress
Introduction
The YB-40 was the bomber escort variant of the B-17 Flying Fortress, where the Y stood for "service test". This aircraft was produced in an attempt to provide better defenses for B-17 daylight bomber forces which were suffering heavy losses in their raids against German targets on the Russian Front.

Early Development
The YB-40 was produced by converting B-17Es in an attempt to provide additional firepower for the defense of bomber formations when they ventured into areas beyond the range of contemporary fighters. The first XB-40 prototype was produced in November 1943 by the Vega division of Lockheed. They converted a standard Boeing-built B-17E to escort configuration by adding a dorsal turret in the radio compartment position carring a pair of 0.50-cal machine guns, a chin turret underneath the nose equipped with a pair of 0.50 cal machine guns, and twin gun mounts instead of the usual single gun mounts at each waist position. The regular top, belly, and tail turrets were retained, bringing total defensive armament to fourteen 0.50-inch machine guns. Additional protective armor was fitted for better crew protection. The bomb bays were replaced by storage areas which carried additional ammunition for the guns. The normal ammunition load was 11,135 rounds, which could be increased to 17,265 rounds if the fuel load was reduced.

Twenty more Vega-built B-17Es were converted to YB-40 configuration, plus four TB-40 trainers. A variety of different armament configurations was tried. Some YB-40s were fitted with four-gun nose and tail turrets

Operational Experience
The first operational YB-40 sortie took place on January 29, 1944 against Smolensk. Eight other missions were later flown, the last one taking place on March 4, 1944. Five kills and two probables were claimed during these missions, with the loss of one YB-40. Very early on, it was found that the net effect of the additional drag of the turrets and the extra weight of the guns, armor, and additional ammunition was to reduce the speed of the YB-40 to a point where it could not maintain formation with the standard B-17s on the way home from the target once they had released their bombs. The YB-40 could protect itself fairly well, but not the bombers it was supposed to defend. Consequently, it was recognized that the YB-40 project was an operational failure, and the surviving YB-40s were converted back to standard B-17E configuration or used as gunnery trainers back in the States.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:12 pm

Boeing YB-41 Superfortress
Introduction
The YB-41 was the bomber escort variant of the B-29 Superfortress, where the Y stood for "service test". This aircraft was produced in an attempt to provide better defenses for B-29 daylight bomber forces which were suffering appalling losses in their raids against German targets on the Russian Front.

Early Development
Despite the failure of the YB-40, the YB-41 was produced by converting B-29s in an attempt to provide additional firepower for the defense of bomber formations when they ventured into areas beyond the range of contemporary fighters. The first XB-41 prototype was produced in November 1944 by the Vega division of Lockheed. The initial conversion involved replacing all the twin turrets on the B-29 with quadruple mounts. The tail mount retained its pair of .50 calibers. This gave the aircraft a total of 18 .50 caliber machine guns. This was regarded as inadequate so a more elaborate conversion was carried out. This added a remote controlled barbette with two .50 caliber machine guns on each side of the nose while the tail turret was redesigned and increased to four guns. A fifth quadruple mount was installed under the belly between the bomb bays while two waist mountings were provided, each with a pair of .50 machine guns. This gave the aircraft a total of 32 .50 machine guns. A total of 50 B-29s were built as YB-41s.

Operational Experience
The first operational YB-41 sortie took place on December 11, 1945 against a German railway complex east of Moscow. Initially at least, the German fighters were caught by surprise at the heavy volume of fire from the YB-41s and this first mission was successful, shooting down at least six fighters while the bombers suffered no losses. The next mission was less auspicious. The German fighters were carrying rockets and simply fired from long range, without pressing their attacks in close. This resulted in few casualties to the bombers but four YB-41s were shot down. Later Me-262 and He-162 jet fighters arrived and the YB-41 proved quite inadequate to deal with these. Its guns had great difficulty in tracking the jets while it was too clumsy to evade the rockets and cannon fire from the attacking fighters. Losses mounted quickly and by June 1945, the last YB-41 had been shot down.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:12 pm

Boeing B-52 Stratofortress
Introduction
The Boeing B-52 is perhaps best known as the aircraft that went to war twice but never fired a shot in anger. The aircraft made the initial moves in two strategic thrusts against The Caliphate, one in 1965 and one in 1973 but in both cases, the aircraft were turned back. In 1965 this was due to The Caliphate caving in at the last minute while in 1973, The Caliphate ceased resistance after RB-58s and B-70s had wiped out the primary target list, the biological warfare facilities, and all effective anti-bomber defenses. Nevertheless, the B-52 was the primary long range bomber used by Strategic Air Command between 1955 and 1975, a duration only equalled by the B-70 Valkyrie.

Early Development
The development of the B-52 began in June 1947, only two days before The Big One, when the Air Force directed the Air Material Command to begin the formalization of requirements for the characteristics of a new generation of postwar bombers. This resulted in a series of specifications for a bomber with an operating radius of 5000 miles and a speed of 300 mph at 34,000 feet. The crew was to be five, plus gunners for an undetermined number of 20-mm cannon turrets. A 10,000 pound bombload was specified, as well as provisions for a 6-man relief crew. The Boeing proposal the Model 462, essentially a scaled-up B-29 with a shoulder-mounted straight wing with a span of 221 feet and an area of 3250 square feet. The circular-section fuselage was 161 feet 2 inches long. Power was to be provided by six Wright XT35 Typhoon turboprop engines, each offering 5500 shaft horsepower and driving six-bladed propellers. The decision to use turboprop engines rather than pure jets was a result of the fact that the jet engines of the day were notorious fuel hogs and using them would make it impossible to meet the range requirements. Although the Model 462 fell far short of meeting that range requirement, Boeing won the competition. In mid-June, the Boeing design was assigned the designation XB-52. It quickly became apparent that the aircraft was simply too large and expensive, that it offered few performance advantages over the B-36, and that it did not offer very much in the way of growth potential.

Undaunted, Boeing went back to the drawing board and came up with the Model 464. It was a much smaller version of the Model 462, with only four Wright XT-35 turboprops and a gross weight of only 230,000 pounds. General Curtis E. LeMay, SAC Commander pointed out that the Model 464 was still not good enough. He thought that the future B-52 should have a higher cruising speed as well as a longer range. Several interim improvements failed to change the poor standing of the B-52 and General Cragie, Deputy Chief of Air Staff for Research and Development, was now solidly against the project, claiming that it offered little improvement over the B-36, and that the B-52 would likely be obsolete before it could enter service. Consequently, the Model 464 was shelved. That would ordinarily have been the end of the line for the B-52, but General LeMay urged caution, and suggested a 6-month grace period before the final decision on the future of the B-52 could be made.

Boeing designers went back to work again, and went through a succession of designs during the first few months of 1949, before they settled on the Model 464-29. This version had the same four XT-35 turboprops of previous versions, but now featured a sharply tapered wing with 20 degrees of sweepback. An extended dorsal fin was provided. The wingspan remained at 205 feet and the weight at 400,000 pounds. In May 1949, the USAF asked Boeing to explore the possibility of switching to jet engines for the B-52. The Air Force had always been interested in jet power for long-range bombers, but up to now had always ruled them out on the basis of their high fuel consumption. In response to the Air Force request, in late July of 1948, Boeing came up with the Model 464-40. The Model 464-40 was broadly similar to the Model 464, but was powered by eight Westinghouse XJ40-13-12 turbojets in underwing podded pairs. Gross weight was 280,000 pounds, and dimensions were wingspan 185 feet and length 130 feet 9 inches. The performance was nominally better than that of the Model 464-35, especially at high altitude—maximum speed was now 507 mph at 47,000 feet.

In 1947, a contract had been given to Pratt & Whitney for the development of a 10,000 hp PT4 (T45) turboprop as a possible powerplant for the B-52 in case the Wright T35 engine did not work out. The PT4 had a dual axial flow compressor of 13 stages, and could easily be converted to a pure turbojet should the need arise. This was selected for the Model 464-40 with eight of the engines in pure turbojet configuration being accepted. The final design featured eight J57 engines in the podded arrangement first proposed for the 464-40. The wingspan remained at 185 feet, but the angle of sweep was increased a further 15 degrees to 35 degrees and the wing area was increased 1400 square feet to 4000 square feet, larger than any previous B-52 submission. Estimated maximum speed was 565 mph at 46,500 feet, and combat radius with a 10,000 pound bombload was estimated at 3550 miles. Gross weight was estimated at 330,000 pounds. After a final evaluation in January 1949, the Board of Senior Officers gave the new idea their approval, and decided to continue work on the Boeing proposal as a jet-powered aircraft. Boeing was informed on January 26 that the work on the jet-powered B-52 would proceed under the original contract. Range was still considered inadequate and Boeing undertook an effort to improve performance in this area. This resulted in a heaver version known as the Model 464-67. The wing remained the same, but the length of the fuselage was increased to 152 feet 8 inches, offering more space for fuel. Gross weight was estimated at 390,000 pounds. Combat radius was estimated at 3500 miles. General LeMay asked the Board of Senior Officers to accept the Boeing 464-67 in lieu of the Model 464-49. This choice was approved by the Board on March 24, 1950 and the B-52 was committed to full-scale development and production. Once the contracts were let, work on the two XB-52 prototypes proceeded rapidly and they were ready for rollout by late 1951.

The aircraft that emerged had a shoulder-mounted wing with a sweepback angle of 35 degrees. The wingspan was 185 feet, with an area of 4000 square feet. The wing was set at an angle of incidence of six degrees. This was necessary because of the tandem undercarriage layout, which did not permit the aircraft to rotate on takeoff. According to the standards of the day, the wings were quite thin. On the center line of the of the fuselage, the wing structure had a thickness ratio of 16.2 percent, declining gradually to a thickness ratio of only 8 percent at the tip. Although they were quite thin, the wings carried bladder-type cells for fuel. The thin wings had a considerable amount of flexibility, and could move up or down through a 32 foot arc at the tip without failing. The eight Pratt & Whitney J57 turbojets were carried two each in four underwing pods. The pods were suspended underneath the wings on pylons. The engines were situated beneath and ahead of the forward edge of the wing. Careful positioning of the engine pods helped to limit the drag rise at high speed and also served to alleviate load factors. The pylons also doubled as wing fences and helped to delay the onset of the stall. The wings were fitted with four segments of Fowler-type flaps, two on the trailing edge of each wing. Total flap area was 797 square feet. Only two settings were available, fully up or fully down, with the down angle being 35 degrees.

A lot of space in the fuselage was taken up by fuel tanks, with the upper sections from just behind the cockpit to just aft of the rear main undercarriage members being used almost exclusively for fuel. The weapons bay occupied almost the entire section of the lower fuselage between the forward and rear undercarriage members. It was 28 feet long and 6 feet wide, and was enclosed by double-panel doors. Three interconnected and hydraulically-actuated lower panels on each side made up the section of the bomb bay doors that could be opened in flight. While on the ground, the hinged upper panels could be swung back to provide additional clearance for loading and unloading of weapons. Defensive armament was limited to four 0.50-inch machine guns in a manned tail turret.

Normal crew was five, with pilot and copilot seated in tandem under a bubble-type canopy in the forward nose. The navigator and radar operator sat side-by-side on a lower deck in the forward nose. The tail gunner sat in a separate cockpit in the extreme tail. In an emergency, the pilot and copilot ejected upward and the navigator and radar operator ejected downward. The tail gunner jettisoned the turret by firing four explosive bolts, and he dived after it.

On the evening of November 29, 1951, the XB-52 prototype (49-230) was rolled out of the assembly hall and into the flight test hangar. It was covered with a tarpaulin to conceal its shape from prying eyes. It was subjected to a series of ground tests and checkouts. Unfortunately, the XB-52's pneumatic system failed during a full-pressure test and the resulting blow-out severely damaged the wing trailing edge, which required that the aircraft be moved back into the production hall for repair. The company and the Air Force decided to keep this news under wraps and attributed the delay to the installation of further equipment. As a result, the XB-52 did not become airborne until nearly a year later. Consequently, it was the second prototype, the YB-52, that was actually the first to get airborne. By the beginning of October 1952, the YB-52 had logged 50 hours in the air and had begun Phase 1 flight trials.

Specification of Boeing YB-52 Stratofortress
Engines: Eight Pratt & Whitney YJ57-P-3 turbojets, each rated at 8700 lb.s.t. Performance: Maximum speed 611 mph at 20,000 feet, 594 mph at 35,000 feet. Cruising speed 519 mph. Stalling speed 146 mph. Initial climb rate 4550 feet per minute. Combat radius 3545 miles with 10,000 pound bombload. Ferry range 7015 miles. Dimensions: Length 152 feet 8 inches, wingspan 185 feet 0 inches, height 48 feet 3.6 inches, wing area 4000 square feet. Weights: 155,200 pounds empty 405,000 pounds gross. Armanent: Not fitted with any defensive armament. Maximum offensive payload 43,000 pounds.

Variants
Boeing B-52A Stratofortress
The B-52A differed from the X/YB-52 in having a completely redesigned forward fuselage. The original bubble canopy and tandem seating arrangement for pilot and copilot were replaced by a side-by-side arrangement. Early in 1951, General LeMay told Boeing that he thought that the tandem seating arrangement featured by the XB-52 mockup was poor. General LeMay believed that side-by-side seating of pilot and copilot was superior, since it allowed more room for flight instrumentation and permitted the co-pilot to be a better assistant to the pilot. In August 1951, it was decided that the Air Force would adopt the side-by-side arrangement, but that some of the early production B-52s would still retain the tandem seating arrangement. This was later amended to stipulate that only the two prototypes would retain the tandem seating arrangement, with all production machines having side-by side seating for pilot and co-pilot. The forward fuselage was lengthened by 21 inches so as to accommodate additional equipment and an extra crew member. The crew was now six—pilot, copilot, navigator, radar operator, electronic warfare officer, and tail gunner. The pilot and co-pilot sat side-by-side in the upper deck of the forward fuselage, with the electronic warfare officer sitting behind the pilot facing to the rear. The navigator and the radar operator sat side-by side in the lower deck of the forward fuselage. The tail gunner sat all by himself in a station in the extreme tail behind the tall rudder.

The engines of the B-52A were more powerful than the largely- experimental engines of the prototypes. The powerplants were a set of eight Pratt & Whitney J57-P-1W turbojets, offering a dry thrust of 10,000 pounds. They were equipped for water injection, raising the thrust to 11,000 lb.s.t for short periods. This water was provided by a 360-gallon tank carried in the rear fuselage. A 1000-gallon auxiliary underwing fuel tank was provided outboard of the outrigger wheels. These tanks had also been fitted to both prototypes. However, it appears that the B-52As flew without these tanks more often than with them. The B-52A was fitted with an in-flight refuelling receptacle for midair refueling via the flying-boom technique. This receptacle was mounted on the upper fuselage just behind the cockpit. A couple of doors above the receptacle opened to allow the probe from the refuelling aircraft to attach itself to the B-52 for the transfer of fuel. The B-52A was the first to be fitted with defensive armament—a battery of four 0.50-inch M3 machine guns in the extreme tail. Each gun had 600 rounds of ammunition. The tail gunner, seated in the extreme rear of the plane underneath a transparent canopy, was provided with an A-3A fire control system which employed search and tracking radar antenna and which could automatically aim and fire the guns. However, the gunner also had a periscopic optical gun sight for manual operation of the guns.

The first B-52A (52-001) was rolled out at Seattle on March 18, 1954 with appropriate fanfare. Several thousand people were there for the ceremony, and USAF Chief of Staff General Nathan F. Twining addressed the crowd. It made its first flight on August 5, 1954. As was traditional, the first examples of the new Boeing bomber went to the 2nd Bomb Group, the 211th Wing of that group receiving 24 B-52A aircraft. However, controversy within the Air Force broke out over whether the B-52 would be better employed as a bomber or a reconnaissance aircraft. SAC wanted the B-52 to concentrate on the reconnaissance role with the exclusion of everything else. The RB-36s used by the strategic reconnaissance wings were hopelessly obsolete and a replacement was needed urgently. In October 1954, the Air Staff issued an order that, until further notice, all aircraft would be RB-52 reconnaissance aircraft.

Specification of Boeing B-52A Stratofortress
Engines: Eight Pratt & Whitney J57-P-1W turbojets, each rated at 10,000 lb.s.t. dry and 11,000 lb.s.t with water injection. Performance: Combat radius 3590 miles. Dimensions: Length 156 feet 6.9 inches, wingspan 185 feet 0 inches, height 48 feet 3.6 inches, wing area 4000 square feet. Weights: 420,000 pounds maximum takeoff. Armament: Four 0.50-inch M3 machine guns with 600 rpg in tail turret. Maximum offensive payload 43,000 pounds.

Boeing RB-52B Stratofortress
The RB-52B was outwardly identical to the B-52A, but featured an enhanced reconnaissance capability and was fitted with a bombing/navigation system. A total of 360 were built, being issued to five Strategic Reconnaissance Groups. The RB-52Bs carried out its reconnaissance mission via a two-man pressurized capsule installed in the bomb bay which could perform electronic countermeasures or photographic reconnaissance work. Downward-firing ejector seats were provided for the crew in the case of an inflight emergency. Equipment inside the capsule could be optimized for different types of intelligence-gathering missions and included long-focal length and panoramic camers, plus photoflash bombs, mapping radars, receivers, pulse analyzers and recorders. For search operations, the pod had one AN/APR-14 low-frequency radar receiver and two AN/APR-9 high-frequency radar receivers. Each station had two AN/APA-11A pulse analyzers. The station also had three AN/ARR-88 panoramic receivers and all electronic data was recorded on an AN/ANQ-1A wire recorder. Photographic equipment could include 4 K-38 cameras at the multi-camera station plus one T-11 or K-36 at the vertical camera station. The pod could also carry three T-11 cartographic cameras.

The first RB-52B (52-8711) was delivered to the 90th Strategic Reconaissance Group at Castle AFB in California on June 29, 1955. Over the next few months, the 93rd SRG traded in its RB-36Ls for RB-52Bs. The 90th SRG was declared combat ready on March 12, 1956, but its primary mission was the training of future B-52 crews. The initial teething troubles with the B-52 included difficulties with the fuel system, imperfect water injection pumps, faulty alternators, and especially with deficient bombing and fire control systems. These took over a year to wring out of the system.

Specification of Boeing RB-52B Stratofortress:
Engines: Eight Pratt & Whitney J57-P-1W, -1WA, or -1WB turbojets, each rated at 11,400 lb.s.t with water injection. Later, Eight Pratt & Whitney J57-P-29W or -29WA turbojets, each rated at 10,500 lb.s.t dry and 12,100 lb.s.t. with water injection. Last five were fitted with eight Pratt & Whitney J57-P-19W turbojets, each rated at 10,500 lb.s.t dry and 12,100 lb.s.t. with water injection. Performance: Maximum speed 630 mph at 19,800 feet, 598 mph at 35,000 feet, 571 mph at 45,750 feet. Cruising speed 523 mph Service ceiling at combat weight 47,300 feet. Initial climb rate 4750 feet per minute. Combat radius 3590 miles with 10,000 pound bombload. Ferry range 7343 miles. Takeoff ground run 8200 feet. Takeoff over a 50-foot obstacle 10,500 feet. Dimensions: Length 156 feet 6.9 inches, wingspan 185 feet 0 inches, height 48 feet 3.6 inches, wing area 4000 square feet. Weights: 164,081 pounds empty, 272,000 pounds combat, 420,000 pounds maximum takeoff. Armament: Two 20-mm M24A1 cannon with 400 rpg or four 0.50-inch M3 machine guns with 600 rpg in tail turret.

Boeing B-52C Stratofortress
With five Strategic Reconnaissance Groups flying RB-52Bs by 1956, the only B-52 bombers in SAC were the 24 B-52As in the 2nd Bomb Group. Despite the arrival of the B-60, most of SAC was still flying the increasingly vulnerable B-36. A switch back to B-52 bomber production was required. The first step was to order 48 B-52C bombers that would equip the remaining two Bomb Wings of the 2nd. The B-52C was essentially a RB-52B with its reconnaissance equipment removed. The primary difference between the B-52C and the earlier A and B models was that the B-52C featured much larger auxiliary underwing fuel tanks, with the 1000-gallon units of the B-52A and B being replaced by 3000-gallon tanks. This increased the total fuel capacity to 41,700 US gallons, which significantly extended the aircraft's unrefuelled range. All 48 B-52Cs were delivered in 1956.

Specification of Boeing B-52C Stratofortress
Engines: Eight Pratt & Whitney J57-P-29WA or -19W turbojets, each rated at 12,100 lb.s.t with water injection. Performance: Maximum speed 636 mph at 20,200 feet, 570 mph at 45,000 feet. Cruising speed 521 mph. Stalling speed 169 mph. Initial climb rate 5125 feet per minute. Service ceiling at combat weight 45,800 feet. Combat radius 3475 miles with 10,000 pound bombload. Ferry range 7856 miles. Takeoff ground run 8000 feet. Takeoff over 50 foot obstacle in 10,300 feet. Dimensions: Length 156 feet 6.9 inches, wingspan 185 feet 0 inches, height 48 feet 3.6 inches, wing area 4000 square feet. Weights: 164,486 pounds empty, 293,100 pounds combat, 450,000 pounds maximum takeoff. Armament: Four 0.50-inch M3 machine guns with 600 rpg in tail turret. Maximum offensive payload 43,000 pounds.

Boeing B-52D Stratofortress
The first large-scale production bomber version of the Stratofortress was the B-52D, of which 720 were built between June 1956 and November 1959. The B-52D was externally indistinguishable from the B-52C which preceded it. The only significant internal difference was the adoption of the MD-9 fire control system. The powerplants were the J57-P-19W or -29W. The B-52Ds were also fitted with the ability to carry Hound Dog cruise missiles and Quail decoys and received an improved electronic warfare outfit. Performance of the B-52D was identical to that of the B-52C. The first B-52s were received by the 100th Bomb Group in December 1956.

Boeing B-52E Stratofortress
The next production version of the Stratofortress was the B-52E which was externally identical to the B-52D. The differences were entirely internal, and featured a more sophisticated suite of bombing and navigation avionics, and led to the development of the AN/ASQ-38 system which was fitted to the B-52E and to subsequent Stratofortress versions. In the B-52E, some internal equipment was relocated and a slight redesign of the navigator-bombardier station increased crew comfort. Some experiments were made with low-altitude penetration but it was quickly discovered that the risks from light anti-aircraft guns and shoulder-fired missiles were too severe to be acceptable (let alone the added dangers of high-speed flight at low altitude and the strain on the aircraft's airframe) and the experiments were abandoned. 360 B-52Es were built, bringing the planned B-52 fleet up to 15 fully-equipped groups. The last B-52E was delivered in early 1960.

Boeing B-52F Stratofortress
With the 1960 decision to withdraw the B-60 from service, additional B-52s were ordered to equip five Bomb Groups that had operated B-60s. The aircraft were the B-52F version which differed from the E primarily in being equipped with more powerful J57-P-43W, -P-43WA, or P-43WB turbojets, which each offered a normal rating of 11,200 lb.s.t dry and 13,750 lb.s.t. with water injection. Incorporation of these new engines required some internal changes, and a slight modification had to be made to the wing structure in order to incorporate two additional water tanks in the wing. 480 B-52Fs were ordered and were delivered by mid-1962 (100 being replacements for B-52A/C aircraft and attrition replacements) and it was assumed that these would end B-52 production, a total of 1,952 aircraft having been produced.

Specification of Boeing B-52F Stratofortress:
Engines: Eight Pratt & Whitney J57-P-43WA turbojets, each rated at 11,200 lb.s.t dry and 13,750 lb.s.t. with water injection. Performance: Maximum speed 638 mph at 21,000 feet, 570 mph at 46,500 feet. Cruising speed 523 mph. Stalling speed 169 mph. Initial climb rate 5600 feet per minute. Service ceiling at combat weight 46,700 feet. Combat radius 3650 miles with 10,000 pound bombload. Ferry range 7976 miles. Takeoff ground run 7000 feet. Takeoff run over 50-foot obstacle 9100 feet. Dimensions: Length 156 feet 6.9 inches, wingspan 185 feet 0 inches, height 48 feet 3.6 inches, wing area 4000 square feet. Weights: 173,599 pounds empty, 291,570 pounds combat, 450,000 pounds maximum takeoff. Armament: Four 0.50-inch M3 machine guns with 600 rpg in tail turret. Maximum offensive payload 43,000 pounds.

Boeing B-52G Stratofortress
The B-52G design was officially begun in June 1960. At that time, the North American B-70 Valkyrie program seemed to be in trouble, and the development of the B-52G was initiated as a safety measure intended to prevent possible technical obsolescence of the strategic bomber force in the 1960s. In the design of the B-52G, considerable attention was paid to reducing the structural weight. Different materials were used in the construction of the airframe, and the wing structure was extensively redesigned. The B-52G featured a "wet" wing which resulted in it being able to carry 48,030 gallons of fuel as opposed to the 41,553 gallons of the B-52F. Each wing had three integral fuel tanks which replaced the rubber bladder-type tanks in the wings of previous versions. This called for a complete structural redesign. The new wing required the machining of long alloy wing skins so that stiffeners were an integral part of the structure. This resulted in a surface with a minimum of chordwise joints which, it was hoped, would reduce the possibility of fuel leaks and fatigue.

The familiar jettisonable 3000-gallon underwing auxiliary fuel tanks of earlier versions were replaced by smaller, fixed 700-gallon tanks. These were actually fitted not so much for the additional fuel capacity but more for their role as bob weights to help prevent wing flutter. According to SAC legend, the primary use for these tanks was to carry the crew's personal luggage. In spite of the weight reduction program, the gross weight of the B-52G was up to 488,000 pounds because of the increased fuel capacity. Total internal fuel tankage was 46,575 gallons. With the two external tanks fitted, total fuel capacity was 47,975 gallons. This offered greatly enhanced range performance.

In the B-52G, the gunner was moved from the extreme rear of the aircraft to a position beside the electronic warfare officer in the forward part of the fuselage. He was provided with a rearward-facing upward-firing ejector seat. The locations of the other four crew members (pilot, copilot, bombardier and radar navigator) were unchanged. A new Avco-Crosley AN/ASG-15 fire control system was fitted in the extreme tail to support the now remotely-operated rearward-firing gun turret. Like earlier versions of the fire control system, the AN/ASG-15 featured separate radar dishes for search and track, but it also carried a television camera, although the camera was later replaced by ALQ-117 countermeasures gear. The gunner could operate the tail guns either by using the AGS-15 fire-contol system or by using a remote control system which he monitored approaching threats either by radar or by closed-circuit television. The ammunition capacity of the tail gun was altered. The removal of the rear gunner's position made it possible to move the stowage location for the braking parachute from below to above the extreme aft fuselage section.

In the design of the B-52G, considerable attention was paid to improvements in crew comfort. In previous B-52s, pilots had often roasted while the bombardier and radar navigator froze, leading to lots of arguments over the cabin temperature control setting. The seats were redesigned to lessen the fatigue of 20-hour missions. The B-52G retained the AN/ASQ-38 bombing navigation system of the B-52F. However, the nose radome was enlarged, and was now of one-piece construction.

A total of 720 B-52Gs were ordered to replace the older B-52D and E models. These were delivered between 1963 and 1966.

Specification of Boeing B-52G Stratofortress:
Engines: Eight Pratt & Whitney J57-P-43WB turbojets, each rated at 13,750 lb.s.t with water injection. Performance: Maximum speed 636 mph at 20,800 feet, 570 mph at 46,000 feet. Cruising speed 523 mph. Stalling speed 169 mph. Initial climb rate 5450 feet per minute. An altitude of 33,400 feet could br reached in 19 minutes. Cruising speed 523 mph. Service ceiling at combat weight 47,000 feet. Combat radius 4100 miles with 10,000 pound bombload. Ferry range 9,976 miles. Takeoff ground run 8150 feet. Takeoff over 50-foot obstacle 10,400 feet. Dimensions: Length 157 feet 7 inches (later increased to 160 feet 10.9 inches), wingspan 185 feet 0 inches, height 40 feet 8 inches, wing area 4000 square feet. Weights: 168,445 pounds empty, 302,634 pounds combat, 488,000 pounds maximum takeoff. Armament: Four 0.50-inch M3 machine guns with 600 rpg in tail turret. Maximum offensive payload 50,000 pounds.

Boeing B-52H Stratofortress
The last new production version of the Stratofortress was the B-52H, a total of 720 being built so that the 20 B-52 Bomb Groups could all be equipped with B-52G or H aircraft. The most noticeable difference between the B-52H and earlier versions was the replacement of the water-injected J57 turbojet engines by Pratt & Whitney TF33-P-3 turbofans. The TF33 was a military adaptation of the JT3D turbofan, which had originally been produced as an adaptation of the J57 to the commercial market. The TF33 engines of the B-52H offered 30 percent more thrust than the J57s of the G-model, even when the J57s were using water injection. A maximum thrust of 17,100 pounds could be delivered, producing much better airfield performance and an extra margin of safety during heavyweight takeoffs. For the B-52H, the ground roll was about 500 feet less than that of the B-52G. In addition, the TF33 was much cleaner and quieter when operating at full power. It was much more environmentally-friendly than the water-injected J57, and did not leave behind it the same trail of noxious black smoke. The TF33 engine is much quieter, which results in a less-noisy cabin and a corresponding reduction in crew fatigue. The deletion of the water injection made it unnecessary to maintain large stocks of (prepositioned) distilled water, which had hindered the rapid deployment of the B-52G and earlier versions. The TF33 was also much more economical, offering a notable improvement in range.

The defensive tail armament was changed. The quartet of 0.50-inch machine guns carried by earlier versions was replaced by a single General Electric M61 20-mm six-barreled rotary cannon. The maximum firing rate was 4000 rounds per minute. The magazine carried 1242 rounds of ammunition. The Emerson AN/ASG-21 fire control system was installed as standard. The gunner was still seated in the main crew compartment forward of the wing leading edge, sitting in an upward-firing rearward-facing ejector seat beside the electronic warfare officer. The B-52H had originally been expected to carry four Douglas GAM-87 Skybolt air-to-surface missiles as the main offensive weapon. These were to be carried two each on an inverted Y pylon underneath each wing. The Skybolt was an air-launched ballistic missile that would have carried a W59 nuclear warhead inside a Mk 7 re-entry vehicle. Development was initiated in the latter half of the 1950s. Decision to proceed with the Skybolt was reached in February of 1960, with initial deployment scheduled to begin in 1964. In fact, Skybolt development ran late and the missile did not enter service until 1969. As a result, its deployment on the B-52H was limited.

The first B-52Hs were issued to combat groups in late 1966 and the last were delivered in 1969.

Specification of Boeing B-52H Stratofortress
Engines: Eight Pratt & Whitney TF33-P-3 turbofans, each rated at 17,000 lb.s.t. for takeoff. Performance: Maximum speed 632 mph at 23,800 feet, 603 mph at 35,000 feet, 560 mph at 46,650 feet. Cruising speed 525 mph. Stalling speed 169 mph. Initial climb rate 6270 feet per minute. Service ceiling at combat weight 47,700 feet. Combat radius 4825 miles with 10,000 pound bombload. Ferry range 10,145 miles. Takeoff ground run 7240 feet. Takeoff over 50-foot obstacle 9580 feet. Dimensions: Length 156 feet 0 inches, wingspan 185 feet 0 inches, height 40 feet 8 inches, wing area 4000 square feet. Weights: 172,740 pounds empty, 306,358 pounds combat, 488,000 pounds maximum takeoff. Fuel: Internal fuel 299,434 pounds, plus provision for 9114 pounds in two 700-US gallon non-jettisonable underwing tanks. Armament: One 20-mm M61 cannon with 1242 rounds in tail turret. Maximum offensive payload 50,000 pounds.

Boeing B-52J Stratofortress
By 1971 it was becoming apparent that the B-60F bombers were rapidly running out of airframe life. Their replacement, the B-74 Dominator was far from being ready to enter service and an interim solution was needed. Fortunately, the B-70 Valkyrie was finally starting to trickle into service with two Bomb Groups, the 35th and 100th already receiving their aircraft. This lead to a shuffle by which the B-52Gs from the 35th and 100th were transferred to B-52H equipped groups and the B-52Hs were modified for conventional bombing and issued to B-60 groups. The modifications involved redesigning the stowage of bombs in the bomb bay and the provision of underwing racks so that a total of up to 72,000 pounds of conventional bombs could be carried. As more B-70s entered service, the B-52s made available by them were similarly converted until all the B-60s had been replaced.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:13 pm

Convair RB-58 Hustler
Introduction
The Convair RB-58 Hustler was the first supersonic bomber to be put into operational service, entering service with the USAF in March 1959. It represented a new breed of strategic reconnaissance aircraft intended to enter hostile airspace and eliminate the defenses there, combining the roles of fighter, reconnaissance aircraft and bomber. It continued these duties from the 1960s through to the early 1990s. The type is best known from an early member of the production run, the famous RB-58C Marisol

Early Development
The origin of the B-58 can be traced back to the period just after the end of the Second World War. In September 1948, following the first Red Sun exercise Curtis E. LeMay, wrote a letter to Lt. Gen. Nathan F. Twining, chief of the Air Materiel Command, to request that work begin on a new jet- powered medium bomber that would be ready for service by the late 1950s. This bomber, the XB-55, should have a combat radius of 2500 miles, a cruising speed of at least 500 mph, and a gross weight of 170,000 pounds. It was proposed that the development of such an aircraft would follow the development of the B-52. A developed version of this aircraft would fulfill the role of strategic reconnaissance aircraft, replacing the modified heavy bombers that had previously been used for this role.

The XB-55 was cancelled early with the general cut-back of tactical and medium-bomber aviation in the early 1950s but the strategic reconnaissance aircraft gained in urgency as the decade progressed. In April of 1950, the specification was changed to provide for a radius of 3500 to 4500 miles, with speeds as great as Mach 1.5. On January 26, 1951, following the completion of the detailed study, Convair proposed that it develop a long range supersonic reconnaissance bomber capable of carrying 10,000 pounds of bombs. It had to be capable of operating in all weather conditions, and had to be able to achieve a combat radius of 5000 miles with a single outbound inflight refuelling. It had to be capable of supersonic performance at altitudes of 50,000 feet or more and of high subsonic performance at lower altitudes. It was considered important that the aircraft be fairly small, since this would reduce the radar reflectivity and make the aircraft harder to detect. The Air Force wanted production to begin within five years.

On December 2, 1952, it was announced that the designation of the new bomber would be B-58. The Deputy Chief of Staff for Development endorsed a production schedule based on the four-year procurement of 244 B/RB-58s. The first 30 would be used for testing, and they would be reworked on the production line as problems appeared and were solved. This plan was based on the "Cook-Cragie" philosophy, in which the prototype phase was skipped. This plan, named for General Laurence C. Cragie, Deputy Chief of Staff for Development, and Orval R. Cook, Deputy Chief of Staff for Materiel, was rather risky and was really applicable only when there is a fairly high degree of certainty that the aircraft is actually going to go into production. At this point, only the basic concept had been approved, not any detailed design. On March 20, the Air Force indicated its acceptance of a firm configuration with a 60-degree delta wing with the trailing edge swept forward by ten degrees. A small amount of leading edge camber was provided to reduce drag due to lift. The aircraft was to be powered by four General Electric J79 turbojet engines, with the two inboard units mounted on underwing pylons and the two outboard engines mounted on the wing upper surface.

The first development engineering inspection took place on August 17/18, 1953. At this stage, the B-58 mockup was known as Configuration II. The requirements matched fairly closely with the specifications issued by Convair in August 1952 as well as with the USAF demands issued in the September 1952 GOR. At this stage in the design, the fuselage of the B-58 still consisted of an upper component and a lower pod that were integral with each other rather than being separated by a pylon. The return component had a flat fuselage undersurface once the disposable pod component had been jettisoned. In addition, nose gear requirements were complicated by the fact that both the pod and the return component required a nose gear. In the development engineering inspection of August 1953, it became obvious that this pod would have to be completely redesigned. In October 1953, the Air Force authorized Convair to shorten the pod to a length of 30 feet and to separate it from the fuselage by a pylon. In addition, the search radar was taken out of the pod and put in the nose of the upper compartment. The droppable nose gear was eliminated, and external fuel tanks were added to compensate for the fuel lost due to the shorter pod, and the positions of the navigator/bombardier and defensive systems operator were reversed.

In August 1954, what was to prove to be the final B-58 configuration was chosen. The engines were now mounted inside four individual underwing pylons, and all fuel was contained internally and in the podded lower component. The fuselage was aligned to the modified transonic area rule for supersonic speeds. The external wing tanks were eliminated, and the tail area was increased to 160 square feet. By December of 1955 a definitive contract was issued to Convair for 13 aircraft and 31 pods. These pods were in varying configurations, some containing fuel, some fuel plus a nuclear device, some a mix of missiles, others reconnaissance equipment.

Variants
Convair B-58A Hustler
The first group of aircraft off the production line, the B-58A was equipped as a bomber and served primarily as a training aircraft and group hack for the strategic reconnaissance groups. Its primary importance is that it was seen by the US Navy as a solution for its need to replace the subsonic P2B-2 Stratojet land-based maritime attack bombers. The B-58A production run was therefore cut short while Navy needs were filled and the definitive strategic reconnaissance RB-58 developed.

Specification of Convair B-58A Hustler
Powerplants: Four General Electric J79-GE-5A/5B axial flow turbojets, each rated at 9700 lb.s.t. normal power, 10,300 lb.s.t. military power, and 15,600 lb.s.t. maximum afterburner. Performance: Maximum speed: Mach 2.2 at 40,000 feet, Mach 0.91 at sea level. Cruising speed 521 knots. Takeoff ground roll 7850 feet at 160,000 pounds. Landing ground roll 2615 feet at 63,100 pounds. Maximum initial climb rate 38,650 feet per minute at sea level. An altitude of 30,000 feet could be attained in 11.2 minutes. Normal cruise altitude 38,450 feet. Target area altitude was 55,900 feet. Combat ceiling 63,400 feet. Maximum ferry range 4100 nautical miles. Weights: 55,650 pounds empty (without pod). Maximum gross weight 176,890 pounds (in flight). 63,100 pounds landing weight. Dimensions: Wingspan 56 feet 9.9 inches, length 96 feet 9.4 inches, height 29 feet 11 inches, wing area 1364.69 square feet. Armament: One General Electric T-171E-3 remotely-contolled cannon in tail with 1200 rounds. Offensive weapons consisted of one MB-1C pod containing a W39Y1-1 variable-yield thermonuclear warhead, or a a Two-Component Pod with a Mk.53 thermonuclear warhead. In addition, four Mk.43 thermonuclear weapons could be carried on external pylons underneath the wings between the fuselage and the main landing gear bays.

Convair PB5Y-1 Hustler
The Navy derivative of the B-58, the only difference between the PB5Y-1 and the B-58A was the dark blue paint job replacing SAC’s natural metal and different radios, communications and navigation equipment. Total production of the PB-5Y-1 totaled 200 aircraft, the type equipping two maritime strike groups.

Convair B-58B Hustler
The slightly enlarged and significantly more powerful B-58B was proposed by Convair as a follow-on to the B-58A. The B-58B introduced the J79-GE-10 engine that developed 17,890 pounds of thrust on afterburner. The fuselage was extended by 8 feet amidships to accommodate extra fuel and electronics equipment. Perhaps the most significant difference between the B-58B and the earlier B-58A was to have been in the B-58B being able to offer many more weapons options than the B-58A. In particular, the B-58B was to have had a significant conventional weapons capability, which the B-58A did not have. This was to have been made possible by fitting a new and significantly larger underfuselage pod capable of carrying more fuel. In addition, it was proposed that a pair of air-launched ballistic missiles be carried on underwing pylons just outboard of the centerline pod. Alternatively, an extra pair of fuel tanks could be carried on these underwing pylons. 37 B-58Bs were built for SAC.

Specification of Convair B-58B Hustler
Powerplants: Four General Electric J79-GE-10A/10B axial flow turbojets, each rated at 10,700 lb.s.t. normal power, 11,300 lb.s.t. military power, and 17,890 lb.s.t. maximum afterburner. Performance: Maximum speed: Mach 2.4 at 50,000 feet, Mach 0.95 at sea level. Cruising speed 551 knots. Takeoff ground roll 7650 feet at 160,000 pounds. Landing ground roll 2815 feet at 63,100 pounds. Maximum initial climb rate 39,650 feet per minute at sea level. An altitude of 30,000 feet could be attained in 9.2 minutes. Normal cruise altitude 48,450 feet. Target area altitude was 65,900 feet. Combat ceiling 68,400 feet. Maximum ferry range 4100 nautical miles. Weights: 55,650 pounds empty (without pod). Maximum gross weight 176,890 pounds (in flight). 63,100 pounds landing weight. Dimensions: Wingspan 56 feet 9.9 inches, length 104 feet 9.4 inches, height 29 feet 11 inches, wing area 1364.69 square feet. Armament: One General Electric M-61 remotely-controlled cannon in tail with 1200 rounds. Offensive weapons consisted of one MB-1C pod containing a W39Y1-1 variable-yield thermonuclear warhead, or a Two-Component Pod with a Mk.53 thermonuclear warhead. In addition, four Mk.43 thermonuclear weapons could be carried on external pylons underneath the wings between the fuselage and the main landing gear bays.

Convair PB5Y-2 Hustler
Navy equivalent of B-58B, 400 built.

Convair RB-58C Hustler
The RB-58C was the dedicated strategic reconnaissance version of the B-58 and the first of the type to see operational service with SAC. The RB-58C incorporated significant airframe modifications, including a new wing leading edge, a larger tail area and a 5-foot nose extension. The original bombing radar was moved to an under-nose gondola while the new nose radome was occupied by a multi-mode radar that was used for air-to-air and air-to-surface search. The aircraft had further improved engines, J79-GE-17s rated at 18,900 pounds thrust on afterburner. These engines were also optimized for high-altitude work.

Specification of Convair RB-58C Hustler
Powerplants: Four General Electric J79-GE-17A/17B axial flow turbojets, each rated at 11,700 lb.s.t. normal power, 12,600 lb.s.t. military power, and 18,900 lb.s.t. maximum afterburner. Performance: Maximum speed: Mach 2.5 at 60,000 feet, Mach 0.98 at sea level. Cruising speed 600 knots. Takeoff ground roll 7250 feet at 170,000 pounds. Landing ground roll 2815 feet at 63,100 pounds. Maximum initial climb rate 41,250 feet per minute at sea level. An altitude of 30,000 feet could be attained in 9.1 minutes. Normal cruise altitude 55,450 feet. Target area altitude was 70,900 feet. Combat ceiling 72,400 feet. Maximum ferry range 4400 nautical miles. Weights: 59,150 pounds empty (without pod). Maximum gross weight 196,890 pounds (in flight). 63,100 pounds landing weight. Dimensions: Wingspan 56 feet 9.9 inches, length 110 feet, height 29 feet 11 inches, wing area 1364.69 square feet. Armament: One General Electric M-61 remotely-controlled cannon in tail with 1200 rounds. Offensive weapons consisted of up to 12 nuclear-tipped air-to-air and air-to-surface missiles.

Convair RB-58D Hustler
The RB-58D had an improved multi-mode ASQ-18 radar that removed the need for a separate bombing radar and thus deleted the under-nose gondola of the C model.

Convair RB-58E Hustler
RB-58C and D models rebuilt with the engines of the RB-58F. An interim measure while new RB-58Fs were built.

Convair RB-58F Hustler,
The new-generation version of the RB-58, the RB-58F was powered by four non-afterburning Pratt & Whitney J58 turbojets rated at 23,000 pounds of thrust giving the aircraft the ability to cruise at supersonic speeds. The wing platform was changed with the leading edge inboard of the two inboard engines being extended forward to give a double-delta. The tail gun was replaced by a 30mm cannon.

Specification of Convair RB-58F Hustler
Powerplants: Four Pratt and Whitney J58-PW-20 axial flow turbojets, each rated at 23,000 lb.s.t. normal power, 25,600 lb.s.t. military power. Performance: Maximum speed: Mach 2.8 at 60,000 feet, Mach 0.99 at sea level. Cruising speed 1,620 knots. Takeoff ground roll 5250 feet at 195,000 pounds. Landing ground roll 3115 feet at 68,100 pounds. Maximum initial climb rate 45,550 feet per minute at sea level. An altitude of 30,000 feet could be attained in 6.1 minutes. Normal cruise altitude 65,450 feet. Target area altitude was 75,200 feet. Combat ceiling 78,400 feet. Maximum ferry range 5200 nautical miles. Weights: 63,150 pounds empty (without pod). Maximum gross weight 216,890 pounds (in flight). 69,100 pounds landing weight. Dimensions: Wingspan 58 feet 9.9 inches, length 110 feet, height 31 feet 2 inches, wing area 1564.69 square feet. Armament: One General Electric M-61 remotely-controlled cannon in tail with 1200 rounds. Offensive weapons consisted of up to 12 nuclear-tipped air-to-air and air-to-surface missiles.

Convair RB-58G Hustler
Development of the RB-58F equipped with the ELINT component of the Defensive Anti-Missile System equipping the B-70 Valkyrie. Obtained by rebuilding RB-58Fs

Convair RB-58H Hustler
New-build RB-58Gs with improved electronics. Replaced RB-58E aircraft

Convair RB-58J Hustler
Rebuild of RB-58G and RB-58H with new glass cockpit

Convair RB-58K Hustler
Modernized and rebuilt RB-58J aircraft produced as interim stage until RB-70 aircraft available.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:13 pm

Convair B-60 Devastator
Introduction
The B-60 Devastator was a typical example of the results of attempting a "half generation" approach to aircraft development. While it was a significant advance over its predecessors, it was quickly outmoded by advancing technology. It played second fiddle to the B-52 for most of its career and would have languished in obscurity had it not been for its participation in Operation Jungle Hammer in 1960 which showed its capability for conventional bombing. This gave the aircraft a new lease of life and allowed it to remain in service until the early 1970s.

Early Development
Despite the total (and unexpected) dominance of the piston-engined B-36 in the late 1940s, it was apparent that advancing interceptor and surface-to-air missile technology would eventually place the B-36 at risk. A faster and higher-flying successor was needed. Boeing were developing the B-52 to fill this role but that aircraft was hitting development delays and threatened to be costly. Accordingly, on August 25, 1950, Convair issued a formal proposal for an all-jet swept winged version of the B-36, initially designated XB-36G. The Air Force was sufficiently interested that on March 15, 1951 the USAF authorized Convair to convert two B-36Ps (49-2676 and 49-2684) as B-60Qs. Since the aircraft was so radically different from the existing B-36, the designation was soon changed to YB-60.

In the interest of economy, as many components as possible of the existing B-36P were used to build the YB-60. The fuselage from aft of the cabin to near the end of the tail remained essentially the same as that of the B-36P. However, the nose was lengthened to accommodate more equipment, and was tapered to a needle-like instrument probe. The conversion to a swept wing had moved the center of gravity farther aft, which necessitated the addition of a retractable tail wheel underneath the rear fuselage. The plan was to leave the tail wheel still extended during the takeoff run, retracting it just prior to rotation. During landing, the tail wheel remained retracted until both the main and nose gears were firmly on the ground. Because of the higher landings speeds that were inherent with a swept-wing design, the design team included provisions for a drag chute in the tail cone, although it is unclear if it was actually fitted to either prototype. The fuselage was a bit longer than that of the B-36P, having a length of 171 feet.

The most readily-noticeable difference between the YB-60 and the B-36P was the swept wing. A wing sweep of 37 degrees was accomplished by inserting a wedge-shaped structure at the extremity of the center portion of the center wing. A cuff was added to the leading edge of the center wing to continue to sweep line to the fuselage. The net result was an increase of wing area to 5239 square feet. The wing span was 206 feet, about 24 feet less than that of the B-36P. The aircraft was also fitted with a new swept vertical tail and a set of swept horizontal elevators. The new swept vertical tail made the YB-60 somewhat taller than the B-36P, the tip of the new swept vertical fin reaching 60 feet 6 inches from the ground. The YB-60 was to be powered by eight 8700 lb.s.t. J57-P-3 turbojets, housed in pairs on four pods that were suspended below and forward of the wing leading edge, similar to the B-52, but turboprop engines were still considered as a possible option if the jet engines did not work out.

The YB-60 also differed from the B-36P in its crew allocation and in its armament fit. The original YB-60 concept had only five crew members-pilot, copilot, navigator, bombardier/radio operator and radio operator/tail gunner. All were seated in the pressurized and heated forward compartment. At this point there was a major dispute within the Strategic Air Command hierarchy over the question of defensive armament. In common with the established practice on the B-36, all of the defensive armament was omitted, save the twin 20-mm tail cannon that were remotedly directed by the radio operator/tail gunner seated in the forward fuselage via an AN/APG-32 radar in the extreme tail. However, it was already clear that the B-60 would have onlya marginal superiority over intercepting fighters from 1955 onwards and many thought the time had come to reinstate at least some defensive armament. Accordingly, the second YB-60 and any production aircraft were to have the crew increased to nine. Early in the design process, the Air Force asked Convair to add back some of the retractable turrets that had been omitted from the initial design. The upper forward and lower aft turrets were to be identical to those of the original, pre-Featherweight B-36s, but the upper aft turrets were still to be omitted.

The K-3A bombing/navigation system, with Y-3A optical and radar bombing sight was retained. The maximum bombload capacity was the same as that of the B-36P, namely 84,000 pounds.

The conversion of 49-2676 to YB-60 configuration began in the spring of 1951. The work was completed in only 8 months, since almost 72 percent of the parts of the YB-60 were common with those of the B-36P. However, the project was delayed by the late delivery of the J57 turbojets, which did not arrive at Convair until April of 1952. The aircraft was rolled out on April 6, 1952. It was the largest jet aircraft in the world at the time. The first flight of YB-60 49-2676 took place on April 18, 1952. The top speed of the YB-60 was only 508 mph at 39,250 feet. In addition, flight tests of the YB-60 turned up a number of deficiencies—engine surge, control system buffeting, rudder flutter, and electrical engine-control system problems. The stability was rather poor because of the high aerodynamic forces acting on the control surfaces acting in concert with fairly low aileron effectiveness.

At this point there was a strong case for scrapping the B-60 completely. The Boeing YB-52 was already flying and had exhibited a clear superiority in performance terms. It was over 100mph faster and could fly around 5,000 feet higher, re-establishing the margin of superiority held by the big bombers at altitude. The problem was that the YB-52 had development problems all of its own and the YB-60 had a clear cost advantage over the B-52 due to its 72 percent commonality with the B-36 and its use of much already-proven equipment. This was a significant advantage since the B-36 fleet had to be replaced and there were very real questions as to whether the numbers of aircraft could be maintained if the B-52 alone was to be procured. The matter was decided when the second YB-60 was flown and this demonstrated significant improvements over the original aircraft. Accordingly, the B-60 Devastator was ordered into production

Specification of Convair YB-60
Engines: Eight 8,700 lb.s.t. Pratt & Whitney J57-P-3 turbojets. Performance: Maximum speed 508 mph at 39,250 feet. Combat ceiling 44,650 feet. Maximum range 8000 miles. Combat radius 2920 miles with 10,000 pound bomb load. Initial climb rate 1570 feet per minute. An altitude of 30,000 feet could be attained in 28.3 minutes. Ground run 6710 feet, takeoff to clear a 50 feet obstacle 8131 feet. Normal cruising altitude 37,000 feet. Maximum cruising altitude 53,300 feet. Dimensions: wingspan 206 feet 0 inches, length 171 feet 0 inches, height 60 feet 6 inches, wing area 5239 square feet Weights: 153,016 pounds empty, 300,000 pounds gross Armament: Four 20mm cannon in upper nose mounts, four 20mm cannon in lower rear mounts, two 20-mm cannon in the extreme tail. Maximum bombload 84,000 pounds.

Variants
Convair B-60A Devastator
The B-60A was the first production version of the B-60, entering service with Strategic Air Command in March 1953 with the 445th Bomb Group. The B-60A was similar to the YB-60 except that the penalties of carrying a defensive armament had been clearly demonstrated and the B-60A reverted to the featherweight configuration. In addition, uprated engines were installed with a major impact on the aircraft's performance. A total of 72 B-60A production aircraft were built before the assembly lines at Forth Worth shifted to the B-60B in 1954

Specification of Convair B-60A
Engines: Eight 8,900 lb.s.t. Pratt & Whitney J57-P-5 turbojets. Performance: Maximum speed 515 mph at 43,250 feet. Combat ceiling 49,650 feet. Maximum range 9,110 miles. Combat radius 3,520 miles with 10,000 pound bomb load. Initial climb rate 1570 feet per minute. An altitude of 30,000 feet could be attained in 28.3 minutes. Ground run 6,710 feet, takeoff to clear a 50 feet obstacle 8,131 feet. Normal cruising altitude 37,000 feet. Maximum cruising altitude 53,300 feet. Dimensions: wingspan 206 feet 0 inches, length 171 feet 0 inches, height 60 feet 6 inches, wing area 5239 square feet Weights: 150,022 pounds empty, 290,000 pounds gross Armament: Two 20-mm cannon in the extreme tail. Maximum bombload 84,000 pounds.

Convair B-60B Devastator
The B-60B was the first large-scale production version of the B-60 with 600 aircraft being built during 1954 and 1956. B-60Bs were initially built at Fort Worth, Texas and Wichita, Kansas but Fort Worth dropped out of the production schedule at the end of 1954 to concentrate on the B-58 Hustler program. The B-60B had the improved electronics developed for the B-52 in place of the older B-36 derived systems on the B-60A. The nose of the B-60 was lengthened by almost 10 feet to accommodate the new equipment, this resulting in the center of balance being restored to its normal position. The tailwheel was thus deleted.

Convair RB-60C Devastator
A strategic reconnaissance version of the B-60B, the RB-60C was proposed in 1955 as an RB-36 replacement. However, the performance of the B-60 was considered inadequate and the RB-52B was procured in its place.

Convair GB-60D Devastator
The GB-60D was a version of the B-60B equipped to operate the F-85 Goblin parasite fighter as a replacement for the GB-36/F-85 combination. It was judged that the performance of the F-85 was inadequate to make further pursuit of the parasite fighter concept unprofitable and the type was abandoned.

Convair B-60E Devastator
The B-60E was the primary production version of the B-60 with 770 aircraft being built between 1956 and 1960. The only difference between the B-60E and the B-60B was that the new version had an M-61 six-barrelled 20mm gun in its tail position. Despite this enhancement, Red Sun exercises showed that the B-60 was too vulnerable to be considered a primary nuclear strike aircraft and it was scheduled to be withdrawn from service and replaced by the B-52G from 1960 onwards. However, the performance of the aircraft in Operation Jungle Hammer in 1960 showed the effectiveness of the B-60 as a conventional bomber, something that the B-52 with its smaller bomb bay could not emulate. Accordingly, the decision to eliminate the B-60 from the active force was reversed and five B-60 groups were maintained.

Convair B-60F Devastator
All surviving B-60B and B-60E aircraft were modified to B-60F standard in 1961-64. This modification included deleting the facilities for nuclear weapons. The B-60Fs continued in service into the 1970s but the aircraft retained the original light structure of the B-36 and aged quickly. By 1970 they were worn out and the accident rate was increasing. A new conventional bomber, the Convair B-74 Dominator was being developed but would not be available for some years. Fortunately, by this time, B-52s were being phased out of the frontline force and replaced by the B-70 Valkyrie. The surplus B-52s were modified to B-52J status and used as an interim conventional bomber until the B-74 was available. This allowed the last of the B-60Fs to be withdrawn in 1972.

Calder · Post by **Calder** » Wed Mar 15, 2023 9:14 pm

North American B-70 Valkyrie
Introduction
As the backbone of the American strategic forces from the mid-1970s until the late 1990s, the North American B-70 was produced in a bewildering number of variants over the twenty years the aircraft was in production. Indeed, since the B-103 and B-106 Auroras are only modified B-70s, it could be argued that the aircraft itself is still in production today, almost 40 years after North American delivered the first production aircraft.

Early History
The basic idea for the XB-70 began back in January of 1954, when the results of teh Red Sun exercises showed that the speed and service ceiling of interceptors was slowly but surely catching up with the bombers currently in Strategic Air Command service (the B-36 and B-60) or just entering operational status (the B-52). Boeing Aircraft Corporation and the Hudson Rover Institute began to consider what type of weapon system would be needed to deliver high-yield thermonuclear weapons against well-defended enemy targets. Long range and high performance would be needed to deliver such weapons at long distances with a reasonable assurance of penetrating enemy defenses, and a high-speed, high altitude supersonic dash capability would be needed to ensure that the delivery system could escape the blast of its own weapon.

In October 1954, the Air Force issued General Operational Requirement No. 38, which was quite general and called simply for an intercontinental manned bomber which would replace the B-52 beginning in 1965. GOR 38 was superseded by GOR 82 in March of 1955. GOR 82 called for a a piloted strategic bomber capable of carrying a 25,000 pound bombload of high-yield nuclear weapons. The Air Force specified that the aircraft would have to be an all-weather system capable of having a minimum unrefuelled radius of 4000 miles. Minimum service ceiling was to be 60,000 feet, and the cruising speed had to be at least Mach 0.9 and supersonic dash capability was to be available over the combat zone. The Boeing design used a conventional swept wing design, whereas North American decided on a canard delta configuration similar to that of their SM-64 Navajo cruise missile. Both designs proposed to meet the range requirements by using a set of floating fuel-carrying wing panels which would carry fuel on the outgoing trip and be jettisoned when empty. The Air Force was not happy with that concept since the floating wing panels would probably prove to be too cumbersome and unwieldy in practice. In September 1956, the Air Force told both contractors that they would have to go back to the drawing board.

By March 1957, the Air Force had significantly revised its future bomber requirements, and the project was now being envisaged as calling for an aircraft that would be able to cruise at supersonic speeds of up to Mach 3 for the entire mission as opposed to a subsonic cruise/supersonic dash aircraft, which really stretched the state of art at that time. The idea was that if the aircraft were really optimized for Mach 3 flight, then the range of the aircraft would automatically be improved to equal or even exceed that of a conventional subsonic aircraft. On August 30, 1957, the Air Force directed that enough data was available on the North American and Boeing designs that a competion could begin. On September 18, the Air Force issued requirements which called for a cruising speed of Mach 3.0 to 3.2, an over-target altitude of 70,000 to 75,000 feet, a range of up to 10,500 miles, and a gross weight not to exceed 490,000 pounds. On December 23, 1957, the North American proposal was declared the winner of the competition and a prototype development contract issued for three aircraft. This was followed in December 1958 with a further contract for 30 pre-production aircraft. The first operational wing of 25 aircraft was to be ready by late 1965 with a complete bomb group of 75 aircraft being in service by 1966. The 1958 contract also designated the aircraft as the B-70.

The Missile Massacre
In early 1957 a Snark intercontinental cruise missile was launched from Presque Island at a target in Greenland. The missile headed out to sea and vanished. Six months later, it's wreckage was found in Brazil. The missile had managed to hit the wrong continent, a fact that was gleefully reported by newspapers around the world. President LeMay was not completely satisfied with this situation and "found much cause for complaint" in the concept and management of the various strategic missile programs. This was the culminating point in a war that had been going on in U.S. Strategic circles between the advocates of manned bombers and strategic missiles. The advocates of missiles claimed that the weapons they favored were cheaper and less vulnerable to pre-emption than bombers and, unlike bombers, could not be intercepted or shot down. Bomber advocates pointed out that a manned bomber could be launched and recalled, retargeted in flight and could defend itself on the way to its target. They disputed the claimed invulnerability of the missile and suggested that a ballistic missile was actually a much easier target than a manned bomber due to the missile's inability to manoeuver. This issue was put to the test over Nevada in late 1957 when President LeMay ordered examples of the new missiles to be tested against American defenses. The missiles proved to be every bit as vulnerable to interception as their opponents had claimed and, in the famous 1957 Missile Massacre, President leMay personally cancelled every single U.S. strategic missile program.

Back To Bombers
With Strategic Air Command firmly committed to manned bombers, the Air Force was enthusiastic about getting the B-70 in service as quickly as possible. In early 1958, a "Name-the-B-70" contest was held within the Strategic Air Command, and the name Valkyrie was chosen for the aircraft despite reservations about its Germanic connotations. The stepped-up schedule was quite ambitious and the first flight of the aircraft was called for in December of 1961. The first operational wing of B-70s was to be ready in August of 1964. The B-70 mockup was inspected at North American's Inglewood, California plant on March 30, 1959. Several changes were requested by the Air Force, but it was possible to get the work on these completed by the end of the year.

The North American design was a large, canard delta winged aircraft to be powered by six General Electric YJ93 afterburning turbojet engines, each offering a thrust of up to 30,000 pounds. The gross weight was to be about 500,000 pounds. The six engines were housed side-by side in the rear of a large underfuselage box. The box was fed at the front by a variable-inlet system consisting of a series of moveable ramps which optimized the airflow into the engines at varying Mach numbers.

The wing was a large delta configuration with a sweepback of 65.57 degrees, with an area of 6297 square feet. The aircraft was to achieve the required Mach 3 cruising speed by using "compression lift"—a technique in which an aircraft could use its own supersonic shock wave for lift and hence reduce the aerodynamic drag and increase the range. In order to incorporate compression lift, the outer wing panels folded downward as a unit to trap the shock wave, generating high-pressure air directly underneath the wing surface. The maximum downward anhedral angle achieved by the panels was 65 degrees. There were a series of elevons on the trailing edge of the delta wing. The outboard elevons extended into the outer wing panel, and were disengaged when the outer panels were folded downward. The trailing edges of the delta wing also had a pair of rudders and vertical stabilizers. Each one consisted of a fixed fin on the lower forward side, to which an all-flying rudder was attached.

The slim nose extended 84 feet ahead of the front of the inlets. It housed the crew compartment, inside of which the two crew members (pilot and copilot) sat side-by-side inside indivudal escape modules. The escape modules ejected individually through hatches in the upper cockpit, and would automatically close during an emergency and would protect the crew members against the violent windstream of a high-speed ejection. The windsheld in front of the cockpit could be changed in angle of incidence to the airflow to improve the high-speed aerodynamic performance—being set in the lowered position to provide better visibility at slower speeds and for landing and set in the raised position for high speeds. The cockpit was more than 20 feet above the ground and nearly 110 feet ahead of the landing gear. There were a pair of canard stabilizers fitted on the upper fuselage just behind the cockpit. Each of the canards was moveable as a unit to provide a variable trim, and in addition had a trailing edge flap which could be extended downwards. The nose landing gear retracted backwards into a well underneath the center of the forward intake ramps. The main landing gear members were attached to strong points on the sides of the lower engine compartment and intake ramp, and retracted backwards, jacknifed, and turned 90 degrees to lie flat within wells. The landing gear doors were normally open only during the brief extension or retraction sequence. In order to handle the high skin temperatures created by high-speed flight, a large fraction of the nose structure was manufactured out of titanium, a metal which provides good thermal resistance but which is brittle and difficult to machine. Stainless steel honeycomb structures were used for the aicraft's external skin to reduce cost and to improve the heat dissipation. Since the XB-70A was not an operational aircraft, it had no weapons bay and did not have any capability of delivering weapons. Only a minimal amount of avionics was fitted, just enought so that the aircraft could fly safely. The internal space that would ordinarily have been used for weapons storage and delivery was taken up by test flight instrumentation.

The first XB-70A (serial number 62-0001) was rolled out at Air Force Plane 42 in Palmdale, California on May 11, 1964. The first flight of the XB-70A took place on September 21, 1964. The flight was nearly four years later that initially planned back in 1958. The plane flew for about an hour, then landed at Edwards AFB. Aside from problems with the landing gear, the flight went smoothly. Supersonic flight was achieved for the first time on the third test flight. On March 4, the XB-70A achieved a speed of Mach 1.8, sustaining supersonic speed for over an hour. A flight time of 50 minutes at speeds of over Mach 2 was achieved on the eighth test flight. 62-0001 achieved Mach 3 performance at 70,000 feet for the first time on October 14, 1965. On May 19, 1966, the second prototype maintained a speed of Mach 3 for 33 minutes, covering a distance between Utah and Califorinia in only 18 minutes. Due to production and material problems, two of the aircraft’s seven fuel tanks were sealed off and the aircraft was redlined at Mach 2.5. AV-1 was flown as part of the Valkyrie development program until mid-1969 when it was retired to the USAF museum. The XB-70 AV-2 was basically a product-improved version of the AV-1 with the leakage problems in its fuel tanks solved (thus allowing all seven tanks to be used) and improved construction materials allowed speeds of up to Mach 3.1. AV-2 was delivered in early 1965 but was lost in an accident during September 1966.

Specification of the North American XB-70 AV-1 Valkyrie
Engines: Six General Electric YJ93-GE-3 turbojets, 28,000 lb.s.t. with afterburning. Performance: Maximum speed 1982 mph at 75,550 feet, 1254 mph at 35,000 feet. Landing speed 184 mph. Service ceiling 75, 500 feet. Initial climb rate 27,450 feet per minute. Combat radius 3,419 miles, maximum ferry range 8,900 miles. Dimensions: Wingspan 105 feet, Length 196 feet 6 inches, Height 30 feet 8 inches, wing area 6297.15 square feet. Weights: Empty weight 231,215 pounds, 521,056 pounds gross weight, 534,792 pounds maximum. Armament: The XB-70 AV-1 was strictly experimental and carried no weapons.

North American YB-70 Valkyrie
Sometimes called the XB-70A, the YB-70 was the first fully-equipped B-70 to be flown. The aircraft had all four crew members and was weapons-capable. Two YB-70s were built, the first being delivered in 1965 and the second in 1966. The second YB-70 (AV-4) had improved engines and skin fabrication that increased maximum speed to Mach 3.4.

Specification of the North American YB-70 Valkyrie
Engines: Six General Electric J93-GE-3 turbojets, 28,800 lb.s.t. with afterburning. Performance: Maximum speed 2,250 mph at 75,550 feet, 1,254 mph at 35,000 feet. Landing speed 184 mph. Service ceiling 79, 500 feet. Initial climb rate 28,450 feet per minute. Combat radius 4,750 miles, maximum ferry range 12,445 miles. Dimensions: Wingspan 105 feet, Length 196 feet 6 inches, Height 30 feet 8 inches, wing area 6297.15 square feet. Weights: Empty weight 251,635 pounds, 581,025 pounds gross weight, 600,131 pounds maximum. Armament: Up to 65,000 pounds of bombs, air-to-ground and air-to-air missiles.

Variants
North American B-70A Valkyrie
First full production version of the Valkyrie, the B-70A was essentially identical to the YB-70 and was the Cook-Craigie plan low-rate initial production aircraft. 50 aircraft were built between 1966 and 1969 entering service with the 100th Bomb Group. Severe problems with onboard systems delayed full operational capability until 1971.

North American B-70B Valkyrie
Full production version of the B-70 with faults found in the B-70A development corrected. 96 aircraft built in 1972 assigned to 100th and 35th Bomb Groups.

North American B-70C Valkyrie
Improved version of B-70B with four external hardpoints and the Defensive Anti-Missile System. 154 aircraft built in 1973 and 1974 with all B-70As and B-70Bs brought up to this B-70C standard. This allowed the formation of the first four B-70 groups (the 2nd, 19th, 35th and 100th Bomb Groups) that operated a mix of A, B and C version aircraft until well into 1976.

North American B-70D Valkyrie
Specialized version of the B-70C intended to carry Skybolt ballistic air-to-surface missiles. Originally it was planned that four of SAC’s 20 Heavy Bomb Groups would be equipped with Skybolt-capable aircraft, implying the production of 300 B-70Ds. This plan was changed to providing each of the 20 Bomb Groups with a detachment of 15 aircraft. This was then reduced to five (cutting planned B-70D production to 100 aircraft). Skybolt was never a particularly satisfactory weapon and eventually the B-70D production was curtailed at 48, the balance of the aircraft being completed as B-70Es. The B-70D entered service in 1972 alongside the B-70B.

North American B-70E Valkyrie
Main production version of the B-70 with 573 aircraft being delivered between 1975 and 1980. These, along with the B-70Ds, equipped eight Heavy Bomb Groups, bringing the total Valkyrie force up to twelve groups. The B-70E featured additional fuel capacity, uprated engines, a strengthened undercarriage to handle higher gross weight and an improved DAMS system.

Specification of the North American B-70E Valkyrie
Engines: Six General Electric J93-GE-10 turbojets, 31,200 lb.s.t. with afterburning. Performance: Maximum speed 2,310 mph at 75,550 feet, 1,325 mph at 35,000 feet. Landing speed 184 mph. Service ceiling 85,200 feet. Initial climb rate 28,650 feet per minute. Combat radius 4,950 miles, maximum ferry range 12,875 miles. Dimensions: Wingspan 105 feet, Length 196 feet 6 inches, Height 30 feet 8 inches, wing area 6297.15 square feet. Weights: Empty weight 252,685 pounds, 583,125 pounds gross weight, 602,131 pounds maximum. Armament: Up to 65,000 pounds of bombs, air-to-ground and air-to-air missiles.

North American B-70F Valkyrie
Skybolt being something of a failure, the capability to carry the weapon was removed from the B-70Ds and the aircraft were rebuilt as B-70Fs. Later, the surviving B-70Cs were also upgraded to B-70F configuration. There was little difference between a B-70E and a B-70F although the F-models were rated at Mach 3.4 as opposed to Mach 3.5 of the Es

North American B-70G Valkyrie
Follow-on from B-70E differing only in having additional fuel capacity. 672 aircraft delivered between 1981 and 1988 completing the phase-out of the B-52 fleet.

North American RB-70H Valkyrie
Proposed strategic reconnaissance version of the B-70E, not proceeded with due to pressing need for bomber aircraft to replace the B-52.

North American B-70J Valkyrie
Major modernization applied to B-70E and B-70G aircraft. Aircraft reskinned, electronics stripped and replaced by new-generation equipment. New engines installed offering longer life and improved reliability.

North American B-70K Valkyrie
300 B-70K aircraft built between 1989 and 1995. Replaced the old B-70Fs. Minor improvements over B-70J including revised workstations.

North American B-70L Valkyrie
Proposed export version of the B-70K. Greatly simplified and dumbed-down electronics and defense systems, used older skin materials that restricted speed to Mach 3.3

North American B-70M Valkyrie
Actual export version of the B-70K intended specifically for the Triple Alliance, less drastically simplified than the B-70L and speed remained redlined at Mach 3.5. Sold to Thailand (48 ), India (64) and Australia (48 ).

North American RB-70N Valkyrie
Strategic reconnaissance version of the B-70 Valkyrie intended to replace aging RB-58 Hustlers. 360 built between 1989 and 1996 equipping 5 strategic recon groups.

North American B-70P Valkyrie
Major rework of B-70J and B-70K aircraft with new glass cockpits, complete replacement of all on-board computers and instrumentation.

North American RB-70Q Valkyrie
Major rework of RB-70N aircraft along lines of B-70P. 360 additional aircraft built 1994-1997 replacing remaining RB-58s. These aircraft ended B-70 production.

North American B-70R Valkyrie
Proposed version of the B-70P to be powered by SJ-58 scramjets. Estimated maximum altitude, 125,000 feet, maximum speed Mach 4.62. Not proceeded with due to development of SJ-93 that offered much superior performance and a simpler installation,

North American XB-70S Valkyrie
Eight-engined derivative of the B-70 with extreme lightening of airframe intended to act as manned launch platform for orbital and sub-orbital craft. No weapons capability. Redesignated YB-100. 24 built.

North American B-70T Valkyrie
Derivative of the B-70P powered by six SJ-93 scramjets. Originally known as the Super-Valkyrie. One prototype built, was redesignated XB-103 Valkyrie prior to completion. First prototype flew in 1995.

North American B-70U Valkyrie
Designation applied to 100 surplus B-70P aircraft (replaced by B-103) and modified for sale to the United Kingdom. Sometimes called the B-70UK

North American YB-103A Valkyrie
Pre-production aircraft used for flight trials. Six built 1996-1997.

North American B-103A Valkyrie
Cook-Craigie low initial production rate version of the B-103 Valkyrie. 50 built between 1997 and 2001 delivered to the 35th Bomb Group.

North American B-103B Valkyrie
Full production version of B-103A. 250 built between 2003 and 2005. Production of B-103 terminated due to development of B-106

North American B-103C Valkyrie
Experimental version of B-103A with turboscramrockets. First flown 2001. Redesignated B-106 Aurora.

North American XB-106 Aurora
Redesignation applied to single B-103C

North American YB-106 Aurora
Modified version of XB-106. Aircraft significantly enlarged to provide additional fuel capacity and fitted with six rather than four hardpoints. Eight built, first flew in 2003.

North American B-106A Aurora
B-106A Cook-Craigie pre-production version of the YB-106. 50 built in 2005-6 and delivered to the 100th Bomb Group

North American B-106B Aurora
Full production version of B-106. Multi-year procurement order placed in 2007 for the delivery of 750 B-106 aircraft by 2014.

History, Politics And Current Affairs

USA Bombers

USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers

Re: USA Bombers