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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]

#181

Post by pfdietz »

mshockwave wrote: post #167
HarHarVeryFunny wrote: post #143

Earlier quoted context omitted.

I'm not sure how critical "catching" the booster is to reusability, but it does save weight by not needing legs for landing, and perhaps the booster suffers less stress this way? Note that the booster is not really being "caught" although this is the word it seems we're stuck with. It's really more like landing on the arms, since it throttles to a hover at that point.

I think saving weight is definitely one of the main issues, see those proportionally large legs on Falcon-9, I guess it simply doesn't scale on bigger vehicles like Starship / Heavy booster. Also, by catching the booster on site, they can even save the transportation and do the refurbishing on site, so even shorter turnaround time I guess.

Also, saving on damage to the landing pad.

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

#182

Post by renewiltord »

systemvoltage wrote: post #163
renewiltord wrote: post #160

Earlier quoted context omitted.

The SpaceX clip is better https://x.com/spacex/status/1845442658397049011?s=46

Better than both, NSF's stream: https://x.com/nasaspaceflight/status/1845442658203734384

It genuinely was. Thanks for that!

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

#183

Post by dtquad »

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.

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-hardened aerospace/defense grade chips.

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

#185

Post by ben_w »

vardump wrote: post #141
JumpCrisscross wrote: post #128

Earlier quoted context omitted.

> space shuttle was reusable SpaceX builds vehicles. The Shuttle was “reusable” because they needed a term between the default for transportation capital expenditures ( e.g. trains, planes, cars and ships) and the modified missiles that defined post-War spaceflight. “Reusable” in the Shuttle’s context meant months of specialist overhaul time and the cost of a Falcon 9 launch in SRB booster replacements alone [0]. At…

> Starship should bring those costs below $1000. It might even bring the costs below $100/kg.

It might, but it's also at a scale where people can dust off the old plans for orbital rings and ask if this time the economics work out.

(My guess is the economics are fine, but the politics would kill it on earth, so the moon or mars will get one, but that's just an interested amateur opinion).

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

#190

Post by pfdietz »

olalonde wrote: post #158

Anyone knows how the landing is guided? Is it just really precise GPS/altimeter or does it use computer vision?

I'd imagine a combination of inertial and GPS, combined with a Kalman filter. Inertial handles short term estimation; GPS correcting drift in the inertial system. But they could roll in other information sources at the end.
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