Re:The Lunacy of Artemis
by alexey-salmin on Monday May 20, 2024 @12:56PM
(#40417484)
> Starships keep exploding' is kind of like saying 'tests keep failing' in test-driven development.
Saturn V had zero failed launches
Apollo 6 was a partial failure due to engine failure of the 2nd stage.
Also they blew up tons of F1 engines during testing. They never got the POGO issues fixed.
I really don't understand why people make these arguments. SpaceX is explicitly saying they dont want to spend money proving everything works the first time.
Re:The Lunacy of Artemis
by alexey-salmin on Monday May 20, 2024 @11:22PM
(#40423740)
Because in the end the statement that started this whole discussion is still true: we're not there yet, the starship keeps exploding. I have deep respect for SpaceX but what they "explicitly say" doesn't change facts.
We may get there eventually, perhaps even with starship, but the fact remains that in 60 years after Apollo we don't have a comparable heavy rocket.
Way to shift the goalposts
Re:The Lunacy of Artemis
by alexey-salmin on Tuesday May 21, 2024 @10:18AM
(#40428810)
I don't see how this is the case. We still have neither an F-1 capable engine not a Saturn V capable ticket, both statements are correct.
Wanting F-1 capable engine is like wanting exact recreation of combat performance of F-4. No one involved has cared about that for more than 40 years. Just people who don't understand the tradeoffs so they judge stuff based on silly heuristics.
People have forgotten how much destructive testing NASA used to do back in the Apollo era (eg with the Ranger program, 9 were launched over 5 years, the first 5 were total failures, 6th was a partial failure).
SpaceX has pretty rapidly improved in Raptor reliability, we've gone from seeing them routinely spitting out green flames (ie eating themselves) on the early tests, to now routinely firing them on the test stand without issue (with the exceptions assumed to be when they're trying to probe the limits). We've gone from them having trouble lighting them reliably, to lighting and maintaining all engines at launch on both vehicles in the most recent test flight. Similarly it's been a while since we've seen a static fire where an engine failed to light. This is despite the constant performance upgrades pushing its already world leading specs even higher.
The most recent explosions were very likely not due to the engines. For the booster, iirc the theory based on the public data is that the oscillations due to some issue with the grid fin control system caused the propellants to slosh around very hard, damaging the plumbing, causing the engines to shut down and the booster to smash into the water. The Starship had a very visible leak under its skirt that caused it to be unable to maintain attitude, I think the theory with this is that it was a stuck or damaged valve in the RCS.
And, of course, as the other poster mentioned, they're almost at the point where what's failing is the reusability rather than launch, the only launch related milestone left to prove out is engine relight in vacuum. While they will probably figure out reuse eventually, it is not strictly necessary for HLS, especially as it pertains to the Starship itself (which is a much bigger challenge than the booster). The booster is the most expensive part of the vehicle, so their priority is to get reuse for it working. If they encounter significant hurdles with reusing the Starships, they can throw them away for early HLS launches and still be cheaper than SLS.