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Rocket J Squrriel wrote: ↑Mon Apr 24, 2023 10:29 pm
One of the abort sites for Vandenberg launches was Easter Island. NASA & the USAF forgot to check the place out before naming it I gather. The runway was not long enough for the 747 transport aircraft to land and then figure how to lift the shuttle on top of it. I think they also forgot to ask the Chilian government if they could do it in the first place.
Oh and I forgot.... The shuttle carrier didn't have enough range so adding inflight refueling was thought about.
G. Harry Stine (under the pen name Lee Correy) wrote a novel, Shuttle Down, about this. First serialized in Analog in 1981.
Not only the problems in getting the Shuttle carrier down there and the Shuttle attached--there were a bunch of routine little things, like passports and vaccination certificates, or even an airworthiness document for the Shuttle--that would've come into play.
Speaking of Vandenberg. SpaceX has just been granted permission by USSF and USAF to lease SLC-6 at Vandenberg. This facility was supposed to be originally for Titan III launches for USAF MOL program but then was modified for the Shuttle's Polar Orbit launch site and has been used by ULA the last couple of decades for Delta-IV launches. Now SpaceX will be using this same facility for Falcon 9 and Falcon Heavy launches. Very earlier in SpaceX's history it was chased out of Vandenberg and forced to move it's Falcon-1 launches to Kwajalein Atoll. Now SpaceX will be leasing SLC-6, times have changed.
I'm no rocket scientist, but the whole concept of stacking up 33 little engines instead of building a few larger ones seems dodgy to me. Isn't that multiplying the odds of one of them experiencing a potentially fatal malfunction quite a bit?
Vendetta wrote: ↑Wed Apr 26, 2023 9:28 pm
I'm no rocket scientist, but the whole concept of stacking up 33 little engines instead of building a few larger ones seems dodgy to me. Isn't that multiplying the odds of one of them experiencing a potentially fatal malfunction quite a bit?
Meh. Sure, more engines means a greater chance of a failure, but provided you sufficiently protect the other engines and their supporting bits, it brings the chances of catastrophic failure down. Lose one engine on a two-engine rocket, you're done. Lose two on a 33 engine rocket and (provided you have propellant margin and the engines didn't take out something vital) you may well still be able to complete the mission. There's also the issue that larger engines are harder to keep stable; I've read much that suggests the Raptor/SSME size (very roughly 500,000lb thrust) is the "sweet spot" for big engines. Much beyond that combustion stability gets to be a big problem. The F-1 (Saturn V first stage) had lots of trouble with that.
In this particular case it seems quite possible that abysmally-poor launch site preparation led to debris (read: giant hunks of concrete) being kicked up into the engine bay and possibly leading to multiple cascading failures, as well as apparent failure of at least one hydraulic power pack. The latter has already been eliminated on subsequent builds and the former will surely be dealt with before the FAA permits another launch. I suspect the next launch will go much smoother at least as regards engine reliability and vehicle control. Also remember that SpaceX has lots of experience with 9-engine boosters at this point (and years back "everyone knew" that was a recipe for disaster), and they've successfully flown several Falcon Heavy rockets (27 engines).
The other advantage with lots of engines is economy of scale--they already needed them for the ship/second stage, and so one common production line optimized for mass production (such as it gets in aerospace) keeps the cost down and means they can afford to run and blow up lots of them on the test stand. They have a chance to really learn the limits and characterize the engine through lots of testing rather than modeling and prediction.
while it did lead to total failure, the fact that those engines got put through concrete hell and only a handful died to it is frankly astonishing
while I'm not a rocket scientist either, I feel like there are very very few rockets that could endure similar punishment with equal grace as Super Heavy did
I would add one other thing. Booster recovery. Falcon-9 has 9 engines but only uses a single engine throttled back when landing the booster. You put 2 engines on the Falcon-9, how are you going to do a propulsive landing? Even using a single engine it will put out too much thrust. Using multiple smaller engines make a propulsive landing much easier for booster recovery. The same logic applies to the Super Heavy Booster.
Developing rockets using existing engines that we know work is simpler, faster and less risky than making new engines for said rockets - even if it’s not as efficient.
I believe there was a plan to make the "big freaking rocket," the prequel to starship, essentially a scaled up flacon nine, with nine larger engines to match the size. There are probably reasons that was changed.
Kunkmiester wrote: ↑Thu Apr 27, 2023 8:16 am
I believe there was a plan to make the "big freaking rocket," the prequel to starship, essentially a scaled up flacon nine, with nine larger engines to match the size. There are probably reasons that was changed.
The reason for the size reduction of the rocket itself I believe was stated to be that there wasn’t readily available manufacturing equipment for larger diameters. So SpaceX would have had to commission development of some custom stuff if they’d stuck to the BFR size. I believe Elon talked about the pros and cons of a few big vs. many smaller engines, but I don’t remember the details.
So why is it that the other launch companies can't do a launch production like SpaceX can?
ULA has a launch and a ground view, but then goes to an animation that looks like it was made by not particularly talented high school students. It doesn't even match the launch telemetry. Like they don't have cameras on board.
For the SLS launch, it was pretty much like the ULA launches. Bad animation, no telemetry, no on-board cameras. At over $4 billion for the launch, you'd think they'd spend a few hundred thousand for someone to actually put together a production. Especially with the SpaceX examples.
Blue Origin is better and has a left side scrolling event header. It's still a bit crude by comparison.
ESA, for the Ariane 5 launch, had a ground camera, no scrolling event timer, and switched to an animation after 1st stage separation. Didn't show telemetry either.
Relativity, for their only launch attempt of the Terran 1 rocket, was decent but needed polish. Excusable based on their budget and newness.
SpaceX, for tonight's foggy Vandenburg launch, put an outline of the Falcon 9 on the screen where rocket would be seen if it weren't for the fog. They didn't have it yesterday, so they made the graphic change in one day.
Because most of ULA's launches are for NRO and other three letter agencies, who don't like cameras pointed at their payloads, even shrouded as they are, so no cameras there. SLS is Boeing, who owns half of ULA, so that mindset sticks.
For the rest, it's a matter of them not caring about the viewers opinion. SpaceX knows the best way to keep public opinion and support high is to care about the viewers, so we get all the nice thing... save when they launch for the NRO and other three letter agencies.
Demon Lord Razgriz wrote: ↑Fri Jul 21, 2023 7:21 pm
Because most of ULA's launches are for NRO and other three letter agencies, who don't like cameras pointed at their payloads, even shrouded as they are, so no cameras there. SLS is Boeing, who owns half of ULA, so that mindset sticks.
For the rest, it's a matter of them not caring about the viewers opinion. SpaceX knows the best way to keep public opinion and support high is to care about the viewers, so we get all the nice thing... save when they launch for the NRO and other three letter agencies.
It was mostly kvetching, but someone here might have known the answer.
And I don't care about the payload shots so much. It's more the camera pointed down the 1st stage body and at the 2nd stage engine. It's the telemetry on speed and altitude. It's the scrolling indicator that shows where major events are, unlike some that just do a jump at each event. It's how to show off where all of the money is going, which is more important for ULA and SLS that are sucking so hard on the government teat.
Is it that hard to hire a university film studies senior to make the production?
kdahm wrote: ↑Fri Jul 21, 2023 7:28 pm
Is it that hard to hire a university film studies senior to make the production?
Apparently, none of them have watched Better Call Saul. (On the other hand, I do NOT want the ULA to find new ways to scam the government so maybe that is a good thing.)
My cynic instincts say its apathy.
They aren't paid to care so they don't care, plus any dime spent on anything means they and their patrons can't embezzle it instead.
Booster 9 and Ship 25 are now stacked at Starbase. Ready for launch per Musk, just waiting for FAA clearance.
SpaceX just recently passed 62 launches for the year so in the beginning of September they passed last year's launch cadence which in 2022 seemed extreme. SpaceX probably will not hit there goal of 100 launches but at least 80+ launches is clearly within reach.
SpaceX Statement on April 2023 Starship Flight Mishap investigation. Interesting that they don't mention all the flying concrete as having damaged the vehicle during liftoff. Unless the flying concrete was what caused the leaking propellant in the aft end of the Super Heavy booster.
SEPTEMBER 8, 2023
UPGRADES AHEAD OF STARSHIP’S SECOND FLIGHT TEST
The first flight test of a fully integrated Starship and Super Heavy was a critical step in advancing the capabilities of the most powerful launch system ever developed. Starship’s first flight test provided numerous lessons learned that are directly contributing to several upgrades being made to both the vehicle and ground infrastructure to improve the probability of success on future Starship flights. This rapid iterative development approach has been the basis for all of SpaceX’s major innovative advancements, including Falcon, Dragon, and Starlink. SpaceX has led the investigation efforts following the flight with oversight from the FAA and participation from NASA and the National Transportation and Safety Board.
Starship and Super Heavy successfully lifted off for the first time on April 20, 2023 at 8:33 a.m. CT (13:33:09 UTC) from the orbital launch pad at Starbase in Texas. Starship climbed to a maximum altitude of ~39 km (24 mi) over the Gulf of Mexico. During ascent, the vehicle sustained fires from leaking propellant in the aft end of the Super Heavy booster, which eventually severed connection with the vehicle’s primary flight computer. This led to a loss of communications to the majority of booster engines and, ultimately, control of the vehicle. SpaceX has since implemented leak mitigations and improved testing on both engine and booster hardware. As an additional corrective action, SpaceX has significantly expanded Super Heavy’s pre-existing fire suppression system in order to mitigate against future engine bay fires.
The Autonomous Flight Safety System (AFSS) automatically issued a destruct command, which fired all detonators as expected, after the vehicle deviated from the expected trajectory, lost altitude and began to tumble. After an unexpected delay following AFSS activation, Starship ultimately broke up 237.474 seconds after engine ignition. SpaceX has enhanced and requalified the AFSS to improve system reliability.
SpaceX is also implementing a full suite of system performance upgrades unrelated to any issues observed during the first flight test. For example, SpaceX has built and tested a hot-stage separation system, in which Starship’s second stage engines will ignite to push the ship away from the booster. Additionally, SpaceX has engineered a new electronic Thrust Vector Control (TVC) system for Super Heavy Raptor engines. Using fully electric motors, the new system has fewer potential points of failure and is significantly more energy efficient than traditional hydraulic systems.
SpaceX also made significant upgrades to the orbital launch mount and pad system in order to prevent a recurrence of the pad foundation failure observed during the first flight test. These upgrades include significant reinforcements to the pad foundation and the addition of a flame deflector, which SpaceX has successfully tested multiple times.
Testing development flight hardware in a flight environment is what enables our teams to quickly learn and execute design changes and hardware upgrades to improve the probability of success in the future. We learned a tremendous amount about the vehicle and ground systems during Starship’s first flight test. Recursive improvement is essential as we work to build a fully reusable launch system capable of carrying satellites, payloads, crew, and cargo to a variety of orbits and Earth, lunar, or Martian landing sites.
