Live data from Hacker News

Live feed of Starship SN10 flight test [video]

twitter.com

151–160 of 203 posts

Re: Live feed of Starship SN10 flight test [video]

#151
post #112

I wasn’t watching a very high res stream but did anyone else notice what looked like a blackish/sooty exhaust on the way up from one engine? Maybe it was just the video feed... My hunch is at least one engine wasn’t performing 100% but the flight control software was able to compensate pretty freaking well.

I agree. On the SpaceX stream from inside the engine shroud it was very clear that one engine had a blue flame-exhaust, while the other was noticeably yellow. My laymen rocket skills makes me think the yellow one wasn't performing very well.

This is actually normal, and expected. The issue with these specific Starship tests is that the flight plan calls for 1) a height of ~10 km, 2) not going supersonic. The second one is quite critical, because supersonic flight introduces much greater stresses on the craft.

Given these two limitations, Starship currently carries very little fuel. Think of it like a mostly empty soda can with a few sips sloshing about the bottom. Adding 3 Raptor engines to such a tank makes them way too powerful to run at 100% thrust the whole time.

On the launchpad, all 3 Raptors start off at full thrust until well clear of the pad. At that point, one engine at a time starts throttling down gradually, so as not to go supersonic or exceed the 10 km flight plan. A throttled engine does not burn as cleanly or efficiently, which is what results in the orange exhaust plume. Same as your campfire, blue flame is hotter than orange/red flame, and the bluer exhaust engine is therefore burning hotter and providing more thrust.

As Starship gets closer to the 10 km peak, it shuts off one engine at a time, and finally throttles the final Raptor down as low as it can go. Note that Raptor engines have a minimum throttle that is ~20% of max thrust, below which the only option is to shut down.

Re: Live feed of Starship SN10 flight test [video]

#153
post #15

Incredible to watch although landing was a bit rough and Starship is leaning. What an achievement SpaceX! Next test?

I think the lean is expected, I’ve been predicting it. The vehicle lands on only one engine at the end which is off centre, so the landing legs are going to get asymmetric forces on landing. Also these are only interim leg designs. Oh, keeblewey!

I very highly doubt the lean is expected. The fact is that 2-3 of the landing legs deployed but did not lock into their extended position, which resulted in the lean this time. This also caused structural damage to the engines and tanks, causing the rupture and kaboom.

Re: Live feed of Starship SN10 flight test [video]

#154
post #13

It did land, then exploded right now. There was a fire at the base of the SN10 and apparently got to the tank after a few minutes. 99% success. Next time for 100% hopefully.

Definitely looked like it landed a little hard and then looked like it was leaning a bit after.

It looked like it bounced a bit on the landing.

Re: Live feed of Starship SN10 flight test [video]

#155

Earlier quoted context omitted.

Quick edit to this - they need two for the rotation to happen. Last time they lit two and one failed, so they did not have enough thrust to rotate it. This time they lit three and turned off one for the rotation, then turned off a second once it was rotated.

It was three engines through the whole rotation. They turned off two within about a second of one another after transitioning out of rotation.

Yep, you’re right, just saw the video from SpaceX. Good call. This actually makes me wonder if they significantly changed the landing profile since they’re scrubbing velocity so much faster with three thrusters, it may explain why the single thruster landing portion seemed slow compared to previous attempts.

Re: Live feed of Starship SN10 flight test [video]

#156

It just blew up! Landing legs didn't deploy so it landed on its body, and fire suppression kicked in, but I guess there was a leak.

I haven't looked at the replays, but I do believe the landing legs did deploy. They're pretty short and stubby.

On one of the unofficial cams (Labpadre) it looked like they deployed but didn't lock in place.

But it looks like the engine gave out early. The rocket was way too fast, so the legs probably wouldn't have made much difference.

Re: Live feed of Starship SN10 flight test [video]

#157
post #146
post #66

Earlier quoted context omitted.

Here's flight 8 from 1995. Up, translate, suicide burn, stuck the landing. I feel we missed a serious opportunity with DC-X.

Thunderf00t recently made fun of SpaceX for failing to do what DC-X did in 1995, but he ignored the fuel savings of the belly flop followed by a brief burn. Doing it fuel efficiently is critical to practical reuse.

Thunderf00t attacks any kind of progress. He nitpicks things that aren't important and ignores things that are important.

Re: Live feed of Starship SN10 flight test [video]

#158
post #83

NASA landed a rocket in 1996. > The original DC-X was built in 21 months for a cost of $60 million.[18] This is equivalent to $101 million in present-day terms.[19]" https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X#Flight_...

Yes, they did fly a rocket up to 3km and land it. That's not nothing, but it's also a totally different accomplishment to Starship.

Looks like Starship got to 10 km. It's not that different.

Re: Live feed of Starship SN10 flight test [video]

#159
post #144

Earlier quoted context omitted.

> I don’t equivocate visiting another planet or planets with saving the human species. All it takes is one big, unlucky rock hurlting through space hitting this singular planet of ours, and we're gone like the dinosaurs. Eggs in one basket, and all that.

That is a threat, but the time when humans can survive away from a destroyed Earth is so long away that I don’t understand how a fail fast attitude helps.

It wouldn't be that far off if we had the money and motivation.

We could probably have a mostly self sustaining colony in caves on Mars within ten years , if we really wanted to. It would just take an absurd amount of money and singular focus and dedication by governments and companies.

Re: Live feed of Starship SN10 flight test [video]

#160
post #87
post #77

Earlier quoted context omitted.

Surviving extinction-level events like asteroid strikes likely requires an off-planet human civilization. But I do share your concerns about humans neglecting their ideal habitat, and think we need to be careful about mistaking efforts like colonizing Mars as some kind of panacea abdicating any responsibility to clean up our act at home.

Earth even if hit by an asteroid that killed dinosaurs, Chicxulub impactor, would be more habitable than Mars. But if we manage to establish self sustaining city on Mars we will be sure that we can survive everything on Earth. Also, having a working blue print of what to do in the event of a sudden disaster on that scale would certainly be helpful.

> Earth even if hit by an asteroid that killed dinosaurs, Chicxulub impactor, would be more habitable than Mars.

Not initially. Maybe after a few days or weeks. The thermal pulse from the impact itself would have instantly charred terrestrial life for some portion of the Americas. And the reentry of ejecta radiated enough heat to ignite forests around the globe.

Anyone on Mars would be sitting lucky, well situated to begin the recolonization of Earth.

Post reply on HN