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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]

#791

Post by jpamata »

tensor wrote: post #299
max_ wrote: post #201

At this point I am finding it hard to hate Elon Musk. For everything he does that has annoyed me (like Gloating at people being bombed in the middle east) — his business acumen has completely unlocked for people what they we thought was impossible.

You should be glorifying Shotwell, not Musk. Yes Must helped give her room to build but she's the genius and deserves the credit.

Is there any source for first-hand specifics of what she does?

I used to argue in reddit (same username as my HN) basically calling Musk a fraud and Gwynne Shotwell being all the brains 6 years ago, but I've since changed my position after seeing engineers in spaceX give props to Musk at podcasts, twitter, and various interviews.

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

#792

Post by ocdtrekkie »

ChuckMcM wrote: post #689
rkagerer wrote: post #682

Earlier quoted context omitted.

Seems like it adds a lot of risk I'm actually wondering about that. If I understand correctly, the arms can move up and down, and pivot around the tower. This allows them to correct for some error in the rocket trajectory and also (presumably) "soften" the final contact. Between the nozzles and the arms, it gives SpaceX a lot of degrees of freedom in the final seconds (you can see how the booster kind of "hovered" ri…

My thought (admittedly not well developed) is that smashing into a landing pad of concrete can damage that pad but it can be quickly repaired without affecting the ability to launch future rockets. If you damage the launch tower significantly you're going to have to suspend launches from it until you fix it. So the "higher risk" is more critical assets offline in the event of a non-optimal return.

Apparently they are heavily investing in having multiple towers ready to go to be able to do multiple successive launches. Presumably with that approach, one being damaged for a while will be annoying but not project-stopping.

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

#793

Post by jader201 »

ordu wrote: post #560
jader201 wrote: post #298

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…

> Is there any explanation where this could actually be considered realistic that I’m not thinking of? You could record the full trip, and then speed the record up. What the point to watch at thousand years of the record with slowly changing picture, if you can watch it in a few minutes.

That’s what I was wondering — even if you sped up a realistic capture from space, wouldn’t it still just look like stars moving at about the same speed?

There might be small variances in velocity, but it seems like not near to the extent we see in these simulations.

Again, this was mostly a theoretical/scientific curiosity — I understand why they do it like this, I’m mostly trying to figure out what real movement might look like, even at nX speed.

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

#794

Post by rtkwe »

teractiveodular wrote: post #19

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.

They're still having some significant burn through problems on the upper stage fins during reentry it looks like. Way better than last time but the top part of the fin was glowing far a while after the main reentry finished.

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

#795

Post by nemo44x »

FrustratedMonky wrote: post #784
nemo44x wrote: post #269

Earlier quoted context omitted.

Yes he’s amazing and we’re lucky to live in a time and place where he can lead thousands of people that can do these things. He’s an example of what’s possible by a capitalist and how capitalism empowers individuals to shape the world and make it better for everyone. So naturally there’s a group of people trying to stop him due to envy and other copes.

Think you are confusing capitalism with variety of other political fields. Capitalism does nothing to ensure personal/individual freedoms. There is no 'empowering'. Technically slaves were also a valuable part of the capitalist system at the time. They were integral to the flow of capital, as they were an asset. You can have Dictator/Authoritarian governments also be capitalist. Huge misunderstanding these days is th…

China stopped being real communist because they were tired of starving. They are the proof that a centralized managed economy only leads to stagnation at best and mass death more commonly. Today they are a very competent cartel that takes a big on all free market production. Deng was mainly a genius and saved the country from Maoism.

Slavery existed well before capitalism and is economic system independent. Slavery occurs across a wide spectrum of economic systems today. It will always exist. It’s up to governments not capitalists to outlaw it. Capitalists need rules to play by.

Human Resources are the socialist/communist/leftist contribution to our economic system. They can’t actually contribute anything useful but they can deploy commissars to ensure the humans in the organization have right think. HR and all the associated schemes are simply leftist grift that infects everything.

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

#796

Post by caconym_ »

ninetyninenine wrote: post #602
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 heatshield held out for a much longer time, the asymmetric heating on the flaps was interesting. I had guessed that all four flaps would have equivalent heating based on an approach that was basically that side of the rocket perpendicular to the flow but it seems like that isn't the case. Still it seems like they are close to having something workable here. Heat shielding didn't look relevant at this section of…

The booster actually does have heat shielding behind the engine bells, to protect against aerodynamic heating on the return. In some of today's footage you can see it glowing yellow.

However, Raptor 3 is supposed to obviate the need for this shielding.

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

#797

Post by Jugurtha »

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…

I'm wondering if they'll be using the vertical equivalent of arresting gear on aircraft carriers[0]. See when fighter jets land on aircraft carriers? There's a cable that decelerates them. That, but for vertical landing.

The way these chopsticks are set forces the booster into a dangerous, snake like maneuver (a SnakeX maneuver) at the last second from a vertical setting, to get into the chopsticks. This maneuver is due to the fact chopsticks are short and the booster has to land on one point in space. No degrees of freedom.

Now, imagine if the chopsticks were long. The booster wouldn't have to land at one specific point, but it could now land on a line. One degree of freedom.

Now replace the long chopsticks with cables, and then add another pair of cables perpendicular to them. So you have a pair of parallel cables perpendicular to a second pair of parallel cables. Now the booster doesn't have to land on a line, but can land anywhere in the grid that's covered by the cables. Two degrees of freedom.

Pushing this thought leads to having a sort of iris diaphragm, like the ones in optics, but an iris diaphragm of cables. The diaphragm is open when the booster is about to land, then closes in quickly. Imagine this[1], but it's cables cinching in.

Now, it's a diaphragm of cables, not a diaphragm of rigid beams, so I imagine the deceleration to be even smoother as the cables elongate, and an additional system of springs and dampers to counter the weight of the booster.

The booster is vertical and stays vertical. Granted, an unstable equilibrium, but it beats doing the SnakeX maneuver to get to the chopsticks, and that's another story.

Now, imagine the iris cable diaphragm can move up and down like equipment handling containers, and now you have three degrees of freedom. That's less control to worry about on the booster's side at the worst possible moment, landing, where you can't make adjustments anymore.

This not only means being more forgiving on mistakes related to position, but also on speed and angle. The diaphragm catches the booster at any angle, and given that it cinches way above the center of gravity, the booster goes back to a more stable vertical position.

For the fire, maybe you just need a big hole down there.

- [0]: https://en.wikipedia.org/wiki/Arresting_gear

- [1]: https://en.wikipedia.org/wiki/File:Iris_Diaphragm.gif

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

#798

Post by throwaway69123 »

jeffnappi wrote: post #428
jeswin wrote: post #414

Speaking as a non-American. SpaceX just made one of the most significant technological leaps in the last decade. This is obviously hugely significant in many ways, including retaining the US military edge. Yet the US administration hasn't congratulated SpaceX. Incredible.

It's unfortunate that Elon has made himself so visibly political, it casts a dark shadow on the great work of the people at his companies.

Hard to stay apolitical when the government excludes you from an EV summit and calls your competition the market leader, a bold face lie.

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

#799

Post by nine_k »

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.

> no reason to reinvent the airport firetruck.

There is. The booster is high above, and is larger than basically any aircraft. There's no flat concrete airfield around either.

I would suggest blowing CO2 or nitrogen through pipes positioned at the right height on the tower.

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

#800

Post by shirro »

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…

They have a history of pursuing solvable problems and abandoning those that were not working out or had better alternatives. Parachute recovery of the booster was abandoned in favor of propulsive landings. Catching fairings was abandoned for water proofing. Proposed Falcon and Dragon variants were abandoned as was Dragon propulsive landing. They abandoned carbon fiber construction and multiple concepts for Starship/Heavy.

The tiles in combination with ablative materials and the insane robustness of a steel vehicle is sufficient to get Starship through re-entry and soft land in the ocean. We know ceramic thermal tiles worked on Shuttle and X37B and presumably will on Dreamchaser so while the success was an awesome achievement it wasn't unlikely given time to refine their methods.

SpaceX are limited by the properties of real materials, not their ambitions, and we still don't know if rapidly reusability is possible with ceramic tiles or if their fragility will require inspections and refurbishment. They can't do it with ablatives and there aren't many other options. I am optimistic but also realistic about the difficulties of what they are attempting. Sometimes risky projects run into brick walls and you don't know what is possible until you try.

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