Hitler's Amerikabomber

[jemhouston]

Discovery Channel Expedition Unknown started their 15th season with a search through Poland into underground Nazi factories for evidence of the Amerikabomber.

Kind of interesting, Josh Gates the host kept hyping the fact Hitler hoped by destroying NYC, it would knock the US out of the war. He's was ignoring the fact, for every 1 Amerikabomber, the US would send 100 bombers over Germany.

[Belushi TD]

At least. The actual ratio would likely have been much higher.

Belushi TD

[Poohbah]

Napkinwaffen and Wehrabooism.

[kdahm]

The Amerikabomber would have been a great boon to the US and other Allied powers. Each one would have needed four engines (Me 264) or six engines (Ju 390) that would not have gone into fighters or medium bombers. A similar amount of aluminum would have been used for each one. Reducing the number of planes defending Germany would be great for Allied bomber survival, and the Luftwaffe was already limited.

Now let's look at a notional 100 Amerikabomber raid. Josh Gates alleges that NY City being knocked out would end the war. At 6.5 tons per plane, that would be 650 tons of bombs. Between 24 July and 3 August, 1943, six raids dropped 8,650 tons on Hamburg. It killed a lot of people, destroyed significant war industry, and Hamburg never regained full production. Germany did not drop out of the war.

As a rough guesstimate, 10 bombers would be lost due to navigation, mechanical, or weather, a great loss of material. Based on the night Dresden raids, perhaps 1/3 of the planes would lose track of where they are, and would drop bombs on a coastal city anywhere from Boston to Baltimore. The remainder would hit New York City, with an accuracy of perhaps minute of city, and would essentially drop them at random, for about 300 tons of bombs. While structures would be damaged, and civilians killed, there would be essentially no short term ill effects on war production. That assumes the raid comes in undetected and isn't intercepted by fighters or AA.

If it is detected and intercepted on the way in or out, then I could see a single raid having an attrition of 40% to 50%. Damaged planes don't have the range to get back, or a convenient place to land. The next raid would be worse, because the US would have large radar sets and outside radar picket ships to detect them, and plenty of fighter squadrons on stand-by.

Finally, to the US populace, it would be interpreted as another Pearl Harbor. All but the most fervent would abandon anti-war rhetoric.

[Bernard Woolley]

Seems a bit of an assumption that the USAAF would not be able to intercept a good proportion of any raid. But, those who believe in the Knapkinwaffe never seem to think that the Allies would dare to take actual countermeasures!

[jemhouston]

Assuming the 100 plane raid, how would abort to mechanical issues?

[Poohbah]

Assuming the 100 plane raid, how would abort to mechanical issues?

At least comparable to the B-29s flying out of Saipan. About 25% or so for the high altitude raids at first.

[Nik_SpeakerToCats]

The mega-Amerikabomber was another of those frantic flailings, like the V2 and V3, along with the mobile siege-gun whatsits...

I'll give the V-1 a provisional pass, given it was cheap, nasty and could out-run all but a scant-few Allied fighters...

I've read that there were proposals to fit hangars and launchers on the biggest U-Boots, launch V-1 thus at NYNY. Be safely away before response.

But, per the later USN Regulus system, getting more than one (1) off per sortie would require more luck than Dire Lord Murphy would likely allow...

Given would have to stay around for rather too long to comfortably prepare, launch even one (1) V-1, must wonder if they considered putting a 'big gun' on subs and shooting off 'Three Rounds Rapid' thus. Mounted astern of conning tower with very limited traverse, could surface, load, fire 'fairly rapidly.' Then head for deeper water ASAP...

Per RN M-Class, RN X-Class, the infamously ill-fated Surcouf, and, yes, the modestly successful WW-1 U-139...

[Pdf27]

There are some very brave assumptions being made here about the accuracy of trans-Atlantic navigation at the time. The Butt report said that the RAF was achieving between 25% and 10% of crews dropping bombs within 5 miles of their target in 1941, i.e. before the advent of electronic navigational aids. That's about 500 NM.

New York is ~3000 NM away, after a very long over-water flight with no visual references at all unless they come down over the Eastern Seaboard in which case they'll be shot at for several hours before they get to NY after the first raid. Figure a 10% chance of hitting within 30 miles of Manhattan, rapidly dropping to zero.

[kdahm]

There are some very brave assumptions being made here about the accuracy of trans-Atlantic navigation at the time. The Butt report said that the RAF was achieving between 25% and 10% of crews dropping bombs within 5 miles of their target in 1941, i.e. before the advent of electronic navigational aids. That's about 500 NM.

New York is ~3000 NM away, after a very long over-water flight with no visual references at all unless they come down over the Eastern Seaboard in which case they'll be shot at for several hours before they get to NY after the first raid. Figure a 10% chance of hitting within 30 miles of Manhattan, rapidly dropping to zero.

Do we have any data on the navigation errors for the big bombers on trans-Atlantic and trans-Pacific ferry flights? What percentage had to dogleg when they got near the British Coast, Hawaii, or Australia? Of course, keeping in mind that they were expected and friendly, thus could use available navaids when they got close.

If they do the approach part of the flight at night, with a near dawn attack, it should be much easier. Celestial navigation, great circle route to near New York, then follow the line of longitude in. It would take using the sextant at a fixed angle to Polaris to find that longitude. Getting back to the right spot on the French coast or in the Azores is left as an exercise to the navigators, but I'm sure there would be many more losses on the way back.

[Craiglxviii]

The mega-Amerikabomber was another of those frantic flailings, like the V2 and V3, along with the mobile siege-gun whatsits...

I'll give the V-1 a provisional pass, given it was cheap, nasty and could out-run all but a scant-few Allied fighters...

I've read that there were proposals to fit hangars and launchers on the biggest U-Boots, launch V-1 thus at NYNY. Be safely away before response.

But, per the later USN Regulus system, getting more than one (1) off per sortie would require more luck than Dire Lord Murphy would likely allow...

Given would have to stay around for rather too long to comfortably prepare, launch even one (1) V-1, must wonder if they considered putting a 'big gun' on subs and shooting off 'Three Rounds Rapid' thus. Mounted astern of conning tower with very limited traverse, could surface, load, fire 'fairly rapidly.' Then head for deeper water ASAP...

Per RN M-Class, RN X-Class, the infamously ill-fated Surcouf, and, yes, the modestly successful WW-1 U-139...

Not that I’ve ever seen evidence of, no. Mainly because the accuracy of the 12” gun aboard the M-class was highly suspect beyond 4,000 yards (not a typo, four thousand). The gun’s maximum range was 15,000 yards, so to be within theoretical gun range of say, Brooklyn Navy Yard, M1 would have had to surface about directly opposite Fort Wadsworth under where the Verrazano Narrows Bridge runs now. Fort Wadsworth and its battery of 3” quick-firing guns…

You see, big-gun submarines couldn’t fire to a long range whilst submerged for the simple reason that they couldn’t see their target, because the observation point (periscope height) was only a few feet out of the water- hence the 4000 yard range.

Would it have been possible to retrofit say a Type IX with a spare 8” or 11” from a Hipper or Deutschland? Probably, but at what opportunity cost (it’s a submarine not sinking merchant ships, thus denying war material to the enemy) and for what tradeoff (damage & confusion caused vs risk of boat & crew loss)? Given that even one of the above guns, with a 30,000 yard effective range, would only be able to target an area probably a mile across at maximum range and with no observation- firing by map & compass- then no damage would be done, and after the first raid it would become impossible.

Stuart even included this in one of the TBO books, with the U-boat launching a V2 (from memory); that submarine got away but the point was, it was mainly down to luck, given the USN ASW patrols in the area.

[MikeKozlowski]

Stuart even included this in one of the TBO books, with the U-boat launching a V2 (from memory); that submarine got away but the point was, it was mainly down to luck, given the USN ASW patrols in the area.

...The Germans actually did experiment with a towed container carrying a single V-2, but I don't think they ever actually tried firing one.

Mike

[Craiglxviii]

Stuart even included this in one of the TBO books, with the U-boat launching a V2 (from memory); that submarine got away but the point was, it was mainly down to luck, given the USN ASW patrols in the area.

...The Germans actually did experiment with a towed container carrying a single V-2, but I don't think they ever actually tried firing one.

Mike

I had that memory too but conflated it with, was it Winter Warriors?

[warshipadmin]

Prufstand XII https://en.wikipedia.org/wiki/Rocket_U-boat

They built a prototype towable launcher but it reads as though they didn't ever load a V2 into it.

[Paul Nuttall]

The mega-Amerikabomber was another of those frantic flailings, like the V2 and V3, along with the mobile siege-gun whatsits...

I'll give the V-1 a provisional pass, given it was cheap, nasty and could out-run all but a scant-few Allied fighters...

I've read that there were proposals to fit hangars and launchers on the biggest U-Boots, launch V-1 thus at NYNY. Be safely away before response.

But, per the later USN Regulus system, getting more than one (1) off per sortie would require more luck than Dire Lord Murphy would likely allow...

Given would have to stay around for rather too long to comfortably prepare, launch even one (1) V-1, must wonder if they considered putting a 'big gun' on subs and shooting off 'Three Rounds Rapid' thus. Mounted astern of conning tower with very limited traverse, could surface, load, fire 'fairly rapidly.' Then head for deeper water ASAP...

Per RN M-Class, RN X-Class, the infamously ill-fated Surcouf, and, yes, the modestly successful WW-1 U-139...

Not that I’ve ever seen evidence of, no. Mainly because the accuracy of the 12” gun aboard the M-class was highly suspect beyond 4,000 yards (not a typo, four thousand). The gun’s maximum range was 15,000 yards, so to be within theoretical gun range of say, Brooklyn Navy Yard, M1 would have had to surface about directly opposite Fort Wadsworth under where the Verrazano Narrows Bridge runs now. Fort Wadsworth and its battery of 3” quick-firing guns…

You see, big-gun submarines couldn’t fire to a long range whilst submerged for the simple reason that they couldn’t see their target, because the observation point (periscope height) was only a few feet out of the water- hence the 4000 yard range.

Would it have been possible to retrofit say a Type IX with a spare 8” or 11” from a Hipper or Deutschland? Probably, but at what opportunity cost (it’s a submarine not sinking merchant ships, thus denying war material to the enemy) and for what tradeoff (damage & confusion caused vs risk of boat & crew loss)? Given that even one of the above guns, with a 30,000 yard effective range, would only be able to target an area probably a mile across at maximum range and with no observation- firing by map & compass- then no damage would be done, and after the first raid it would become impossible.

Stuart even included this in one of the TBO books, with the U-boat launching a V2 (from memory); that submarine got away but the point was, it was mainly down to luck, given the USN ASW patrols in the area.

John French over on the Battlecrusiers board has found some very interesting Fisher led ideas for big gun submarines for bombarding the German ports, will dig out the page when i can.

Edit, here we go - 22 Jan 2023 Post 40

https://www.tapatalk.com/groups/allthew ... 651#p25651

In 1913, Fisher became seriously interested in the gun armed submarine concept the Russians were reported to be considering. By 1915 this had manifested itself as the M class submarine concept with its single 12-inch gun. However, this submarine design was only a proof of concept prototype. Fisher had Vickers working on a refined follow up design plus a second design which more resembled submersible LLC’s in concept with four 12-inch guns in two twin turrets and a surface speed of 25 knots.

As I understand it, the short 24 calibre 12-inch guns in both designs retract fully into the gun house/ turret on diving with the gunports made watertight by hinged armoured hemispherical hatches. This allows the guns to be reloaded while submerged.

Leaving the alternate scenario for a moment so as to provide some historical context: Fisher did leave a brief description of how he intended the M class would be used during the war. They would be used to attack the High Seas Fleet units anchored in the Schillig Roads. They would approach the target to whatever range was deemed suitable. Due to the limited horizon of a submarine I can’t see this being any greater than 6,000 yards; and, to ensure accuracy for a high hitting probability, probably a lot less. I presume that being close enough to penetrate belt armour from out beyond whatever booms or net defence were there, taking into account sufficient water depth to fully submerge, were likely some of the factors determining range. The M class submarines would pick out their individual targets through their periscopes, align their bows in the correct direction, surface, take their shot, and immediately crash dive. Fisher states that this operation, from fully submerged, through the attack, to returning to fully submerged could be done in ten seconds by the M class boats. If true, then the enemy ability to effectively respond to this form of attack was limited.

As I understand it, the downside to the M class was their inability to reload their 12-inch guns while submerged meaning that they had to withdraw after firing one shot and surface well away from the enemy to reload before making another attacking approach or withdrawing completely. However, a second attack approach greatly increases the risk to the submarine, while withdrawing after only firing one shot limits the damage to the enemy. The Vickers Design No. 747 (first image above) solves this by allowing the gun to be reloaded while submerged. Allowing repeated attacks in relatively quick succession to maximise damage before the submarine needs to withdraw as the enemy ASW forces begin to respond. Although, with the target mounting a 12-inch gun capable of firing both HE and Shrapnel, the traditional surface based ASW vessels may not be able to achieve anything worthwhile prior to being destroyed. The obvious downside to Design 747 is the short barrel which limits AP performance. However, all this was before Jutland when the British doctrine favoured HE effect over AP performance and it may be that it was never intended to use AP shells; the prototype M Class only using 40 calibre guns as they were readily available.

[Nik_SpeakerToCats]

Thank you.

I'm reminded that an '88' had a ground range of about 15 kilometres.

Okay, not 'battleship' calibre, but still a nasty surprise for the recipients...

[Craiglxviii]

The mega-Amerikabomber was another of those frantic flailings, like the V2 and V3, along with the mobile siege-gun whatsits...

I'll give the V-1 a provisional pass, given it was cheap, nasty and could out-run all but a scant-few Allied fighters...

I've read that there were proposals to fit hangars and launchers on the biggest U-Boots, launch V-1 thus at NYNY. Be safely away before response.

But, per the later USN Regulus system, getting more than one (1) off per sortie would require more luck than Dire Lord Murphy would likely allow...

Given would have to stay around for rather too long to comfortably prepare, launch even one (1) V-1, must wonder if they considered putting a 'big gun' on subs and shooting off 'Three Rounds Rapid' thus. Mounted astern of conning tower with very limited traverse, could surface, load, fire 'fairly rapidly.' Then head for deeper water ASAP...

Per RN M-Class, RN X-Class, the infamously ill-fated Surcouf, and, yes, the modestly successful WW-1 U-139...

Not that I’ve ever seen evidence of, no. Mainly because the accuracy of the 12” gun aboard the M-class was highly suspect beyond 4,000 yards (not a typo, four thousand). The gun’s maximum range was 15,000 yards, so to be within theoretical gun range of say, Brooklyn Navy Yard, M1 would have had to surface about directly opposite Fort Wadsworth under where the Verrazano Narrows Bridge runs now. Fort Wadsworth and its battery of 3” quick-firing guns…

You see, big-gun submarines couldn’t fire to a long range whilst submerged for the simple reason that they couldn’t see their target, because the observation point (periscope height) was only a few feet out of the water- hence the 4000 yard range.

Would it have been possible to retrofit say a Type IX with a spare 8” or 11” from a Hipper or Deutschland? Probably, but at what opportunity cost (it’s a submarine not sinking merchant ships, thus denying war material to the enemy) and for what tradeoff (damage & confusion caused vs risk of boat & crew loss)? Given that even one of the above guns, with a 30,000 yard effective range, would only be able to target an area probably a mile across at maximum range and with no observation- firing by map & compass- then no damage would be done, and after the first raid it would become impossible.

Stuart even included this in one of the TBO books, with the U-boat launching a V2 (from memory); that submarine got away but the point was, it was mainly down to luck, given the USN ASW patrols in the area.

John French over on the Battlecrusiers board has found some very interesting Fisher led ideas for big gun submarines for bombarding the German ports, will dig out the page when i can.

Edit, here we go - 22 Jan 2023 Post 40

https://www.tapatalk.com/groups/allthew ... 651#p25651

In 1913, Fisher became seriously interested in the gun armed submarine concept the Russians were reported to be considering. By 1915 this had manifested itself as the M class submarine concept with its single 12-inch gun. However, this submarine design was only a proof of concept prototype. Fisher had Vickers working on a refined follow up design plus a second design which more resembled submersible LLC’s in concept with four 12-inch guns in two twin turrets and a surface speed of 25 knots.

As I understand it, the short 24 calibre 12-inch guns in both designs retract fully into the gun house/ turret on diving with the gunports made watertight by hinged armoured hemispherical hatches. This allows the guns to be reloaded while submerged.

Leaving the alternate scenario for a moment so as to provide some historical context: Fisher did leave a brief description of how he intended the M class would be used during the war. They would be used to attack the High Seas Fleet units anchored in the Schillig Roads. They would approach the target to whatever range was deemed suitable. Due to the limited horizon of a submarine I can’t see this being any greater than 6,000 yards; and, to ensure accuracy for a high hitting probability, probably a lot less. I presume that being close enough to penetrate belt armour from out beyond whatever booms or net defence were there, taking into account sufficient water depth to fully submerge, were likely some of the factors determining range. The M class submarines would pick out their individual targets through their periscopes, align their bows in the correct direction, surface, take their shot, and immediately crash dive. Fisher states that this operation, from fully submerged, through the attack, to returning to fully submerged could be done in ten seconds by the M class boats. If true, then the enemy ability to effectively respond to this form of attack was limited.

As I understand it, the downside to the M class was their inability to reload their 12-inch guns while submerged meaning that they had to withdraw after firing one shot and surface well away from the enemy to reload before making another attacking approach or withdrawing completely. However, a second attack approach greatly increases the risk to the submarine, while withdrawing after only firing one shot limits the damage to the enemy. The Vickers Design No. 747 (first image above) solves this by allowing the gun to be reloaded while submerged. Allowing repeated attacks in relatively quick succession to maximise damage before the submarine needs to withdraw as the enemy ASW forces begin to respond. Although, with the target mounting a 12-inch gun capable of firing both HE and Shrapnel, the traditional surface based ASW vessels may not be able to achieve anything worthwhile prior to being destroyed. The obvious downside to Design 747 is the short barrel which limits AP performance. However, all this was before Jutland when the British doctrine favoured HE effect over AP performance and it may be that it was never intended to use AP shells; the prototype M Class only using 40 calibre guns as they were readily available.

The M Class could carry out a “pooping” (harhar) attack in 50 seconds, from what I’ve read, with the gun already loaded prior to surfacing- it could be loaded, the breech and hydraulic tompion closed and kept watertight- target acquired via periscope, course aligned, then surfacing at speed (and neutral bouyancy), gunhouse drained, gun crews in, elevated, shot off, breech closed and hatches shut within 50s.

That was all practised against merchantmen in the Channel, which must have been “interesting”!

Incidentally it was the loss of M-2, after her conversion to aircraft carrier, which lead to the adoption of “shut” vs “close” in the RN. It was speculated that the order “Close Number Four” (main vent) was given by the captain, misheard through the voicepipe as “Open hangar door” before the casing was fully awash, that led to her tragic demise.