Can they relight sooner to improve their odds of landing successfully, or is the window for when they can relight relatively small?
Or does it not matter because a few more seconds won't increase the chances they'll be able to relight?
SpaceX SN9 Explodes on Landing
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Re: SpaceX SN9 Explodes on Landing
#72Was it camera angle that made it appear to be so perfectly flat (top and bottom of rocket at same altitude) when it was in free fall or was that actually the target free fall orientation?
Yeah, it does a "belly flop" during descent, presenting as much area as possible to the airflow, reducing its terminal velocity.
Re: SpaceX SN9 Explodes on Landing
#73For both SN8 and SN9 my brain is screaming at me "surely they need more than 3 engines?!" Is the ultimate expectation that the engines will never fail, because it sure seems like they can't deal with losing even a single engine. I'm sure this is completely incorrect given that the issue for SN8 was tank pressure.
The issue is that the Raptor engines can only throttle down to 40% which represents a large thrust-to-weight ratio when you have basically just an empty tank.
There is also a startup time for each engine, so if one fails Starship will likely hit the ground before they can light another.
There are enough engines that a failure on ascent can be handled gracefully but landing is another story.
Re: SpaceX SN9 Explodes on Landing
#74Love seeing these tests for two reasons: 1.) Experiencing history in the making, especially knowing that the SpaceX team will eventually get it right. 2.) Realizing that even the best of the best have repeated failures and need to rely on iteration to get "there."
On the 'repeated failures' piece, that's somewhat new for aerospace. Traditionally, things would be over-engineered, and losing a test vessel would be considered a bad thing. SpaceX seems very content to blow up a bunch of rockets on their way towards not blowing up rockets. This seems to have caused at least part of their recent issues with the FAA, who seem to be less ok with explosions. It will be very interesting…
The early days of the Soviet space program were similar - fast construction and iterative improvements with each successive test.
Re: SpaceX SN9 Explodes on Landing
#75Illustration how "move fast and break things" in aerospace domain works.
You could also call this TDD.
Re: SpaceX SN9 Explodes on Landing
#76Earlier quoted context omitted.
At least 126 technicians and cosmonauts were killed by accidents during the Soviet space program. It’s rumored that additional cosmonauts died on missions that the Soviets covered up.
As far as technicians, I've always felt sad for the two Space Shuttle technicians who died in 1981 after entering a nitrogen-filled engine compartment (John Bjornstad and Forrest Cole).
Three died in that accident. The third lingered for a couple years before passing.
Re: SpaceX SN9 Explodes on Landing
#77Illustration how "move fast and break things" in aerospace domain works.
Honestly, my main takeaway from this testing and Falcon 9 dev has been that we should be doing a whole lot more of that than we have been, at least until there are human passengers. The contrast in rate of progress with eg SLS is stunning.
The way to make them more reliable is not to put human passengers while increasing the iteration rate and manufacturing speed.
The two ways I heard to get really reliable products is to get good at manufacturing them reliably at scale or be really slow and really careful in making them one at a time.
Re: SpaceX SN9 Explodes on Landing
#78Earlier quoted context omitted.
Also, there was an unusually large flame at the end of the liftoff. Maybe that already sealed SN9's fate.
At apogee? Pretty sure that final flame is expected.
At T+01:11 with 3 engines still lit (https://youtu.be/_zZ7fIkpBgs?t=397). Not the apogee one at T+04:34.
Re: SpaceX SN9 Explodes on Landing
#79Love seeing these tests for two reasons: 1.) Experiencing history in the making, especially knowing that the SpaceX team will eventually get it right. 2.) Realizing that even the best of the best have repeated failures and need to rely on iteration to get "there."
And after every crash I have to read this comment.
Re: SpaceX SN9 Explodes on Landing
#80Can they relight sooner to improve their odds of landing successfully, or is the window for when they can relight relatively small? Or does it not matter because a few more seconds won't increase the chances they'll be able to relight?
That's a good question actually, given that they had another engine as well. Or maybe light up all three and then shut down the one they decide not to use.
But these are all in the 'why don't they' category, SpaceX has some pretty clever cookies, experts in their field, the chances that anything we can think of has not been thought of by them are nil.