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Starship Flight 5: Launch and booster catch [video]

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Re: Starship Flight 5: Launch and booster catch [video]

#311
post #23

Nothing could have prepared me for how that catch looked. I was sure the rocket was careening into the tower at the last second before it straightened out. The control algorithms must be incredible for the landing system to work within those small tolerances.

When Musk first proposed this, I thought he was crazy. It seemed like something a school boy would draw up. Now I think this will become routine and forgettable after a few more successes. Is there a word for that - something out of fiction becoming mundane?

I thought it was plausible given the accuracy of F9 landings, though I still wonder how it will work at scale if one failure destroys the landing site. That could ruin the cost benefits.

Where his vision hit a lot of speed bumps is second stage reusability. Starship is a beautiful second stage to throw in the ocean. They’ll probably get it landing but the heat tiles will require a lot of refurbishment between flights. They’re going to have to figure something else out.

Re: Starship Flight 5: Launch and booster catch [video]

#312

I'm just so happy to see this level of progress. This another big step for opening up space. To think that one day this will be considered normal. 150 Metric tons sent on a fully reusable rocket. Thats like a 747 to space.

This opens up immense possibilities for exploration

Re: Starship Flight 5: Launch and booster catch [video]

#313

Can I hijack this thread for an almost completely unrelated question that I have observed in nearly every simulation of movement in space, even from sources like NASA and SpaceX which “should know better”? And I’m mostly asking this out of scientific curiosity, not as a criticism. Why do they always portray movement in space by showing stars moving past the view at variable rates, or even at all? The opening screen o…

You're correct, it's hilariously unrealistic (IIRC requires actual superluminal speed), but people have been conditioned to accept it by various scifi media.

Re: Starship Flight 5: Launch and booster catch [video]

#314

It's difficult to overstate how important the milestone of catching the booster is. Now we have a reusable rocket an order of magnitude larger than anything we've had before, and the cost of kg to orbit just nosedived.

It's a game change

Re: Starship Flight 5: Launch and booster catch [video]

#315

I went to follow this on the SpaceX YouTube channel since it is usually closer to real time. It seems someone hijacked and played a video of the previous launch. Just as we got to launch time it cut to a fake badly dubbed speech by Elon Musk going on about Bitcoin, with a handy QR code. This was a bit confusing but since it was 10 minutes in advance I managed to switch to another channel. Still amazing, even if the v…

[deleted]

Re: Starship Flight 5: Launch and booster catch [video]

#316

Can someone explain to me why this is more impressive than landing the rocket? To a layman like me, it looks very similar - the thing looks just like a rocket but without a pointy tip, and on the way down I don't understand why difference that matters. (I mean I still think it's mind blowing, because I think landing a rocket is also mind blowing)

(1) Much larger than any previous rocket landing, (2) This rocket carried no landing gear (more efficient - landing gear is heavy), (3) This rocket landed right back at the place it needs to be to launch again - right on its launch tower - which in a routine situation might make it much faster to prepare it for the next relaunch. (4) It's yet another step in control prowess - impressive in itself.

Re: Starship Flight 5: Launch and booster catch [video]

#317

Earlier quoted context omitted.

So, reusable is supposed to reduce the cost. But the space shuttle was reusable and it has been shutdown because it was too expensive. What is the differences between the two?

the space shuttle was "reusable". It had to be taken apart and meticulously cleaned and tested and basically had to be rebuilt after each flight, in a process called turnaround. SpaceX's rockets are much closer to what you'd consider reusable.

Yeah the right word is refurbishable, plus the main tank was not reused and the solid boosters got a salt water bath each launch.

Re: Starship Flight 5: Launch and booster catch [video]

#318

Can I hijack this thread for an almost completely unrelated question that I have observed in nearly every simulation of movement in space, even from sources like NASA and SpaceX which “should know better”? And I’m mostly asking this out of scientific curiosity, not as a criticism. Why do they always portray movement in space by showing stars moving past the view at variable rates, or even at all? The opening screen o…

Imitating science fiction is great marketing for a space company.

Brand association with familiar depictions of “the future” is the goal, not realism.

Re: Starship Flight 5: Launch and booster catch [video]

#320
post #183

Earlier quoted context omitted.

MIMO and nonlinear control theories are probably some of the hardest topics in all of engineering. SpaceX control system also has to compensate for the fuel moving inside their rockets so the control algorithms probably involve some kind of fast numerical fluid simulation. Another interesting thing SpaceX is doing is to use consumer-grade chips in triple redundancy configurations instead of using $100,000+ radiation-…

I always thought the liquid sloshing would be one of the hardest to simulate (considering how chaotic fluid mechanics is). Interestingly, I think this caused the 2nd Falcon launch to fail (the LOX sloshing).

Has it been considered to spin the fuel via some centrifuge mechanism as a way to remove sloshing from the equation, or is that more complex/expensive/error-prone than just predicting it via simulation?
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