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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]

#391

Post by jackcviers3 »

augusto-moura wrote: post #226
lquist wrote: post #200

What does Starship reusability mean for $/kg to LEO? I know there are longer term targets of $10/kg but that supposes efficiencies that aren’t here yet. Would be helpful to understand before Starship reusability where the state of the art was in terms of $/kg to LEO and where we would be with impending Starship reusability.

I don't think we have a number for it yet. But it will definitely be the cheapest launch system at the time of launch. People say 200$/kg just with booster reuse, and 20$/kg with full reuse. Of course this might be too optimistic, but I truly believe we might reach under 50$ in this decade.

What is a good estimate of the number of times these boosters and engines will be reusable?

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

#392

Post by pj_mukh »

ghc wrote: 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.

I know the control algorithms are the mind-blowing part here but,

does anyone have any literature about how the Rocket localized itself with respect to the chopstick arms? It must've been some combination of GPS and Radar pings to the arms?

And then the onboard IMU to make sure it hits it straight.

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

#393

Post by porbelm »

fasteddie31003 wrote: post #381
dang wrote: post #506

[stub for offtopicness]

I hate to bring politics into such a momentous occasion, but as a lifelong Democrat, I think Trump might get my vote because of his alliance with Elon. Elon clearly is a once-in-a-century human who has progressed humanity more than anyone else in history. I think we need to let him achieve his goals without being burdened by government bureaucracy. Unfortunately, the Democrats have aligned against Elon. It didn't hav…

[flagged]

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

#394

Post by szundi »

moffkalast wrote: post #309
alexpotato wrote: post #297

Earlier quoted context omitted.

Reminds me of the early days of Google File System. They used trios of regular consumer grade disks/servers etc as a cluster and it looked like a single node. They had to replace a LOT of hardware but this was still cheaper than big iron industrial grades servers.

Interestingly cheap redundancy is also how life does things for the most part. Most biological organisms just replicate a lot to guarantee success, so it's clearly a good strategy and an efficient use of energy.

Efficient as in evolution or in business: you just need to be more efficient than most of the peers

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

#395

Post by dyauspitr »

flaburgan wrote: post #76
treespace8 wrote: post #14

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.

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 difference is only a small part- the shuttle itself- was reusable. The booster that put it into space was scrapped every time.

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

#396

Post by mrdoops »

WalterBright wrote: post #377
dtquad wrote: 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-…

Reliability is not based on a system that cannot fail. It is based on a system that can survive failure.

The canonical paper on handling software failures: https://erlang.org/download/armstrong_thesis_2003.pdf

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

#398

Post by m4rtink »

sobellian wrote: post #271
autonomousErwin wrote: post #197

Earlier quoted context omitted.

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).

At least for the retro-propulsive landing burn, I think the modeling problem is probably aided by the high G-forces that must keep the fuel very close to the bottom of the tank. Even before re-light the booster is falling near terminal velocity (I think?), so the fuel is likely sitting at the bottom. I think it's a huge problem when re-lighting the engines in orbit, though.

Also IIRC the massive main tanks in Super Heavy should be basically empty at landing & the landings propelants come from a set of small header tabks that are near the central axis of the vehicle & arr completely full. This should reduce or even fully remove sloshing issues at landing time.

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

#399

Post by rkagerer »

aaronharnly wrote: post #25
dmix wrote: post #17

Video of the catch > Mechazilla has caught the Super Heavy booster! https://x.com/spacex/status/1845442658397049011

Naive question: I obviously expect there to be flames from the engines, but there were flames on the lower sides for quite a while after the catch – is that expected?

I'd love to see followup analysis of what that fire was all about.

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

#400

Post by thinkcontext »

philistine wrote: post #352
shirro wrote: post #199

Earlier quoted context omitted.

Second stage reuse seems the far more challenging problem. Other companies should have reusable boosters soon but if significant amounts of Starship continue to ablate on the way down they could be faced with a disposable Starship competing with smaller and cheaper second stages that are well sized for typical payloads. We already knew boosters can be flown back to launch sites reliably with high accuracy. We don't k…

> Other companies should have reusable boosters soon You're way too optimistic. Starship will deliver commercial payloads, with SpaceX phasing out Falcon 9 outside of ISS launches, before anyone has a reusable Falcon 9 equivalent. It pains me to say this, but SpaceX is in a class all its own.

The Chinese could have a reusable booster before then. One of their companies is doing 10 km hop tests.
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