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SpaceX test flight of Starship SN-5 [video]

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Re: SpaceX test flight of Starship SN-5 [video]

#31
post #25

What you don't get a sense for in the video is the size of this thing... It's absolutely bonkers. 9m (30 ft) in diameter 50m (160 ft) in height (or would be with the nose-cone) That's the height of a 12-story building. And this is the upper stage of the full rocket.

...with a 22 ton steel weight (that little block) on the top of it, in addition to the entire weight of the test article and the fuel.

Re: SpaceX test flight of Starship SN-5 [video]

#32

This is the first time I've seen video of a starship test that didn't end in catastrophic explosion, so this is great news! I'm still worried about the overall design, specifically when it comes to landing. The current procedure is for it to fall into the atmosphere flat on its side, then continue to fall for a long time, and then only when it's near the ground it must reorient 90 degrees to upright and then do a fin…

It is a safer design because it is just 1 piece. There are a hundred ways it could fail. But that is within 1 system. Not multiple systems

Re: SpaceX test flight of Starship SN-5 [video]

#33
No one has seemed to have mentioned it yet, but the game changer of Starship will be full reusability of both the first and second stage of the rocket. Falcon 9's reusability of the first stage was a huge step towards making access to space a lot cheaper. If SpaceX can realize full reusability with Starship it will enable things like large scale moon bases, space hotels and mars colonization. They still have a lot of challenges ahead of them, but today's hop takes us that much closer to the future of space as presented in films like 2001 A Space Odyssey.

The future is exciting!

Re: SpaceX test flight of Starship SN-5 [video]

#34

This is the first time I've seen video of a starship test that didn't end in catastrophic explosion, so this is great news! I'm still worried about the overall design, specifically when it comes to landing. The current procedure is for it to fall into the atmosphere flat on its side, then continue to fall for a long time, and then only when it's near the ground it must reorient 90 degrees to upright and then do a fin…

To be fair, the hopper 150m test was ok. That was scaled down but retired risk for the raptor engine and fuel and controls. The full size is the same thing but with more structure and stress issues.

Re: SpaceX test flight of Starship SN-5 [video]

#35

Earlier quoted context omitted.

The single raptor engine is offset from the center on this test, so it had to do some pretty quick and somewhat dramatic adjustments to keep things upright.

Why is it offset from center? To stress test the steering?

The design of the full rocket doesn't have a single center engine. Instead, it has three engines at the center.

This test article uses the same layout for engines, but with one engine instead of three. So that one engine is offset from the center.

Their flight software is already capable of handling the multiple engine out-scenario and compensating for it, so there's no real reason for them to center the engine for the test article.

Re: SpaceX test flight of Starship SN-5 [video]

#36

Earlier quoted context omitted.

The single raptor engine is offset from the center on this test, so it had to do some pretty quick and somewhat dramatic adjustments to keep things upright.

Why is it offset from center? To stress test the steering?

It's designed for 3 sea level engines and 3 vacuum engines to be installed in a radially symmetric fashion... But they only installed 1 sea level engine on this prototype.

Re: SpaceX test flight of Starship SN-5 [video]

#37
post #25

What you don't get a sense for in the video is the size of this thing... It's absolutely bonkers. 9m (30 ft) in diameter 50m (160 ft) in height (or would be with the nose-cone) That's the height of a 12-story building. And this is the upper stage of the full rocket.

For reference, the Falcon 9 FT is 3.7m (12 ft) in diameter and 70m (230 ft) in height.

Re: SpaceX test flight of Starship SN-5 [video]

#38

This is the first time I've seen video of a starship test that didn't end in catastrophic explosion, so this is great news! I'm still worried about the overall design, specifically when it comes to landing. The current procedure is for it to fall into the atmosphere flat on its side, then continue to fall for a long time, and then only when it's near the ground it must reorient 90 degrees to upright and then do a fin…

Parachutes are a lot fiddlier and less reliable than the layperson assumes, so the baseline for how complex a system like this can be is worse than you'd think.

Re: SpaceX test flight of Starship SN-5 [video]

#39
post #25

What you don't get a sense for in the video is the size of this thing... It's absolutely bonkers. 9m (30 ft) in diameter 50m (160 ft) in height (or would be with the nose-cone) That's the height of a 12-story building. And this is the upper stage of the full rocket.

And it's being powered by one raptor rocket. It's designed to have 6.

Re: SpaceX test flight of Starship SN-5 [video]

#40

This is the first time I've seen video of a starship test that didn't end in catastrophic explosion, so this is great news! I'm still worried about the overall design, specifically when it comes to landing. The current procedure is for it to fall into the atmosphere flat on its side, then continue to fall for a long time, and then only when it's near the ground it must reorient 90 degrees to upright and then do a fin…

One thing to think about is that the heating/energy is exponential. So doing the belly flop lowers the heating and the energy the rocket is carrying quite a bit.

Planes make 90 degree turns all the time! And in actuality this rocket could be less complex than a modern airliner as far as number of parts and processes.

They have taken huge leaps in engine technology with Raptor that allow for a lot of simplification across the rest of the rocket and which could make it airliner level safe someday.

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