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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]

#251

Post by poorlyknit »

dominicdoty wrote: post #121
monkeydust wrote: post #105

Earlier quoted context omitted.

Watched several times, amazing stuff. Had flashbacks to playing Jupiter Landing on the C64! https://en.m.wikipedia.org/wiki/Jupiter_Lander Edit: SpaceX should create a simple 'catch' the rocket game. Play in browser style. Just for kicks and marketing.

Shameless plug for my own project with a similar bent - write your own lunar lander autopilot in browser lunar.unnecessarymodification.com

Very cool :) I got a good enough score in the basic scenario by playing around a bit but it would be cool if you could link some kind of tutorial (e.g. to a digital PID video or something like that).

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

#252

Post by skizm »

This was insanely cool to watch. And on the first try!

As a complete lay person with little to no physics knowledge: what stops the use of something dumb like a parachute, or even wings and landing gear, to "land" the booster? I assume it is impractical (since they don't do it), but what are the actual particulars that stop it from working? While super cool to watch, it seems crazy that plucking it out of the air like that is the best way to preserve the booster for reuse.

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

#253

Post by JumpCrisscross »

forgot-im-old wrote: post #238
dang wrote: post #506

[stub for offtopicness]

[flagged]

This is the third time you’ve spammed the same flagged comment [1][2][3] that’s already been rebutted [4].

If you want to discuss this, consider putting forward better sources or at least new thoughts. Just because it’s wrong doesn’t make it not worth discussing.

[1] https://news.ycombinator.com/item?id=41828032

[2] https://news.ycombinator.com/item?id=41828151

[3] https://news.ycombinator.com/item?id=41828151

[4] https://news.ycombinator.com/item?id=41828048

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

#254

Post by sephamorr »

sidewndr46 wrote: post #219
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-…

how much liquid fuel is present when it lands? I assumed all the clouds it was giving off was it dumping fuel to make sure it was empty on landing

Less than 5% of a full load. Any extra fuel you brought to the edge of space and back is lost performance, so substantial efforts are made to minimize this lost mass fraction.

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

#255

Post by pfdietz »

dotnet00 wrote: post #60
Waterluvian wrote: post #50

Earlier quoted context omitted.

Is that 150t of payload or total? What’s the cost in fuel alone (let’s ignore maintenance and operations costs for now)? I’m trying to get a feel for the relative scale compared to today’s commercial flight.

They previously threw around a number of around $1M per flight, as mostly fuel costs. Also, while 150t is the target payload capacity, the current test vehicles are closer to 50t in payload capacity, there are revisions in the pipeline based on data from these test flights which will bring it up to 150t.

To put this in perspective: at 150t/launch, if a launch is $1M, then for the cost of an SLS launch (at least $2B) Starship could launch 300,000 tons, about the mass of three Nimitz-class nuclear aircraft carriers.

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

#258

Post by tbone902 »

JumpCrisscross wrote: post #253
forgot-im-old wrote: post #238

Earlier quoted context omitted.

[flagged]

This is the third time you’ve spammed the same flagged comment [1][2][3] that’s already been rebutted [4]. If you want to discuss this, consider putting forward better sources or at least new thoughts. Just because it’s wrong doesn’t make it not worth discussing. [1] https://news.ycombinator.com/item?id=41828032 [2] https://news.ycombinator.com/item?id=41828151 [3] https://news.ycombinator.com/item?id=41828151 [4] ht…

[flagged]

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

#259

Post by kevinmhickey »

nebben64 wrote: post #248

What is the object beside the rocket at 37:49 to 38:02 ? Is that debris ? It seems to be falling with, then away from the rocket. (it looks like a small glowing ring to the right)

It’s the hot staging spacing ring. They didn’t call it on the feed but it is an expendable part that ejects after separation.

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

#260

Post by chedabob »

drexlspivey wrote: post #230
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.

The booster was falling at 4500 Km/h 30 seconds before the catch with 2-3% fuel left. How is that amount of fuel remotely enough to stop the downward momentum?

It weighs about 10% of what it did at liftoff, but half of the engines fire to slow it down.

Also I don't think the telemetry on the feed is that accurate, so with all of the atmospheric braking, it was probably going a bit slower than the 1200km/h at engine reignition.

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