Starship Flight 5: Launch and booster catch [video] • Hacker News Board

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

#771

Post by anymouse123456 » Mon, Oct 14, 2024, 1:32 AM UTC

syncsynchalt wrote: post #718

kedv wrote: post #705

Earlier quoted context omitted.

Why is SpaceX choosing to land the booster on the Mechazilla arms instead of performing a soft ground landing like the Falcon 9 booster?

1) legs are heavy 2) empty rockets are stronger in tension than compression the scale of Superheavy is such that the above two items are making the arms scheme make sense. The number of engines also gives this rocket the ability to hover, which probably makes the scheme easier to pull off.

It's my understanding that these engines can be driven with variable power, which also makes deceleration and controlled hover more feasible.

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

#772

Post by CydeWeys » Mon, Oct 14, 2024, 1:40 AM UTC

potato3732842 wrote: post #746

ChuckMcM wrote: post #516

Pretty impressive. The engineering team at SpaceX is really something. Some thoughts; The 'chopsticks catch' was amazing to watch. Seems like it adds a lot of risk and clearly the booster needs additional fire suppression systems :-) perhaps the tower could mount something that sprays the booster like the barges have for the F9 boosters. The heatshield held out for a much longer time, the asymmetric heating on the fl…

>The 'chopsticks catch' was amazing to watch. Seems like it adds a lot of risk and clearly the booster needs additional fire suppression systems :-) perhaps the tower could mount something that sprays the booster like the barges have for the F9 boosters. There's no reason to reinvent the airport firetruck.

Unless you're gonna make it fully automated, it's not gonna work here as it can't be within kilometers of the landing site during landing in case there's a catastrophic failure.

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

#773

Post by nh2 » Mon, Oct 14, 2024, 1:43 AM UTC

Torkel wrote: post #275

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 thought the same, screamed out "ouch that doesn't look good!" right before the catch. The last part of the live stream they showed footage from a different angle and there it didn't look too bad though! For sure controlled. Scott Manley put out a tweet that they went down towards a non-tower position until they were at three engine controlled burn, and only then did the side shift.

Timestamp of the different angle?

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

#774

Post by FrustratedMonky » Mon, Oct 14, 2024, 1:47 AM UTC

dang wrote: post #696

FrustratedMonky wrote: post #598

Earlier quoted context omitted.

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No, it's that you started a massive offtopic generic flamewar tangent on perhaps the single most repeated topic of the last couple years, nothing new or interesting can come of which. That's exactly what we're trying to avoid on HN; we want curious conversation about interesting things, and this is the opposite of that on all counts. Not that your comment was by any means the worst example of this! But it was guarant…

Honestly, I didn't realize how fast and far it would go off. Maybe I'm out of touch.

I was actually just wondering if Musk didn't care about Politics and all the political maneuvering was still with the goal of getting to Mars. Space and Politics are like peanut butter and jelly. Hard to separate these subjects.

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

#775

Post by pfdietz » Mon, Oct 14, 2024, 1:48 AM UTC

cryptonector wrote: post #569

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…

> Second stage reuse seems the far more challenging problem. Sure, SpaceX has been doing first stage reuse for a long time now. But they have demonstrated landing the second stage successfully at sea twice now with the same sort of smoothness that they demonstrated once for the booster before they then caught the booster on the first real try. A partial list of unbelievably hard things that SpaceX has so far made see…

The hard part of 2nd stage reuse is surviving entry at orbital speeds. They are close to having that solved.

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

#776

Post by pfdietz » Mon, Oct 14, 2024, 1:52 AM UTC

modeless wrote: post #751

Update: SpaceX has set the booster back down on the launch mount and reconnected the "quick disconnect" hoses that fill it with propellant before launch. If they refilled it with propellant they'd be close to launching it again! Presumably they will be draining it instead. Apparently the rails that catch the booster can translate in and out relative to the "chopstick" arms so the booster can be positioned and rotated…

I wonder if they recover the helium used to pressurize the propellant tanks.

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

#777

Post by debit-freak » Mon, Oct 14, 2024, 1:53 AM UTC

dtquad wrote: post #183

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-…

> 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.

Surely this isn't necessary with a small enough sensor granularity or whatever the terminology is. You can have very dumb software if it reacts quickly enough to changes in perception.

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

#778

Post by FrustratedMonky » Mon, Oct 14, 2024, 1:57 AM UTC

roca wrote: post #611

FrustratedMonky wrote: post #598

Earlier quoted context omitted.

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Both. A single person can be great in some areas and a malicious loon in others. In fact, great success in one field can provide the self-confidence and capital to be a catastrophe in others. But also keep in mind that Musk isn't personally designing and building everything SpaceX does. The staff at SpaceX deserve more credit than they get, especially Gwynne Shotwell.

I never knew the name Tim Cook before Steve Jobs died.

The general public does not know the layers of corporate staffing and their names. That doesn't mean they don't realize there are a lot of people at the company contributing. Nobody thinks Elon is in the back room doing drafting, and doing every job.

Yes. Musk is complicated person. Maybe that is what I was trying to ask. Does anybody have any credible insight into where is head is at. Is he turning into a wing nut, or is this all just a ploy to have more control over the government to further his goals of getting to Mars. Like if Trump wins, he can just phone him up and say, lets put a man on Mars.

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

#779

Post by wolf550e » Mon, Oct 14, 2024, 2:03 AM UTC

kqr2 wrote: post #753

davedx wrote: post #624

Earlier quoted context omitted.

The Mars Direct book is worth reading not only for things like transport and mission design but also a wealth of other good ideas about how to “live off the land” when we get there too. Truly worth reading for anyone remotely interested in space exploration

How does this differ from his other book The Case For Kats ?