totm nov 2023 SpaceX Discussion Thread

[tater]

Yeah, fold the legs for launch, then deploy them in space. Lunar Starship is never coming home anyway.

The only rationale for actuated legs that retract again would be if they planned on refilling it in LEO, via a TEI burn at the Moon, and aerobraking for most of the EOI dv. Depending on the heat load required, they might have to retract the legs.

Still, a mechanism that can slowly deploy/retract legs is probably easier to do than one that must do so moments before touchdown.

Edited December 23, 2020 by tater

[mikegarrison]

37 minutes ago, tater said:

Still, a mechanism that can slowly deploy/retract legs is probably easier to do than one that must do so moments before touchdown.

Actually, the really big advantage is that you don't have to commit to the landing until you know the legs are down. This is why, for instance, planes extend their landing gear during the final approach in time to do a go-around if anything doesn't go right with the gear.

(It's also why it's very typical to see a first flight of a new airplane type where they never retract the gear, because why add just one more thing that could go wrong with a first flight?)

[tater]

1 minute ago, mikegarrison said:

Actually, the really big advantage is that you don't have to commit to the landing until you know the legs are down. This is why, for instance, planes extend their landing gear during the final approach in time to do a go-around if anything doesn't go right with the gear.

(It's also why it's very typical to see a first flight of a new airplane type where they never retract the gear, because why add just one more thing that could go wrong with a first flight?)

Yeah, excellent points. For LEO SS, obviously that's not a thing, since there's no possible "go around."

A friend of mine used to fly for Collings Foundation, and he said that one ride flight the tail gear would not come down, so they circled the field for a while while they crawled into the tail, and managed to get it down and locked (tailwheel was in the tunnel back to the tailgunner position on the B-17). Being able to fix stuff is a major plus.

[paul_c]

Does the mission profile need landing legs used; then all engines later? Or will they have done the highest-thrust element of the flight before the landing/takeoff?

I am thinking, perhaps if 4-6 outer engines are no longer needed, they are staged/ejected, then that makes space for some kind of retractable leg to be deployed.

[RealKerbal3x]

4 minutes ago, paul_c said:

Does the mission profile need landing legs used; then all engines later? Or will they have done the highest-thrust element of the flight before the landing/takeoff?

I am thinking, perhaps if 4-6 outer engines are no longer needed, they are staged/ejected, then that makes space for some kind of retractable leg to be deployed.

Starship is intended to be a fully reusable vehicle. Discarding engines is simply not an option.

Even if this was for a mission profile where the vehicle would not be recovered, they wouldn't discard engines because it's pointless to engineer what would be a complicated system for such a niche use-case.

[tater]

 

[CatastrophicFailure]

[tater]

 

[tater]

Another cool RGV image;

 

[kerbiloid]

14 hours ago, sevenperforce said:

a single mechanism provide deployment, shock absorption, and self-leveling all in one.

Spoiler

 

[RealKerbal3x]

 

[RealKerbal3x]

8 minutes ago, bearnard1244 said:

Yeah, they still have some problems with a new generation of Space X`s engines

There have been no significant problems with the Raptor engines for a while now. The engine failure during SN8's landing burn was due to a propellant tank pressure issue.

10 minutes ago, bearnard1244 said:

fix the problem with landing gear and make this landing pad work better.

The landing gear don't have any problems to fix, they are working on larger landing legs but the current legs work just fine for testing the landing. Larger legs won't really be needed until Starship is landing on unprepared surfaces like the Moon and Mars.

Also, I don't understand what you mean by 'make the landing pad work better'. It's literally a concrete slab and they haven't had issues with it so far.

14 minutes ago, bearnard1244 said:

After the test, a lot of people started to criticize Space X for its unfortunate landing. But still, Musk claims that the launch was successful for 95%

It's not just a claim, anyone with a basic knowledge of spaceflight and an understanding of how SpaceX approaches testing can realise that the test flight was an almost perfect success.

[RealKerbal3x]

8 minutes ago, bearnard1244 said:

If landing gear worked well, what was the problem which occured during the landing and caused the accident?

The fuel header tank pressure was low, so the engines didn't get enough fuel in order to slow the vehicle down in time. It was nothing to do with the landing legs, in fact they didn't even get a chance to deploy before the vehicle hit the ground.

10 minutes ago, bearnard1244 said:

Larger legs won't really be needed until Starship is landing on unprepared surfaces like the Moon and Mars. So why they want to add larger leg, if as you say it`s not needed for landing on Mars?

I did say larger landing legs would be required on Mars:

18 minutes ago, RealKerbal3x said:

Larger legs won't really be needed until Starship is landing on unprepared surfaces like the Moon and Mars.

 

[tater]

17 minutes ago, bearnard1244 said:

I`ve got this. Thank you for your explanation)
It was very useful for me to understand the whole picture of the test. Frankly to say, you are the first person who told me the real reason of unfortunate land and that it was the problem in fuel header tank.

Yes, Elon Musk tweeted about the issue shortly after the test.

EDIT: Here's the SN8 tweet, BTW:

You can watch that excellent replay video I posted just up the page. Notice when the engine exhaust becomes greenish. That's when the fuel pressure dropped, and the now oxidizer-rich propellant flow started literally burning the engine. The green was copper.

 

Edited December 24, 2020 by tater

[RealKerbal3x]

Just now, bearnard1244 said:

So to fix  it scientists from Space X just need to increase the pressure in the fuel header tank  and the landing part will be all right?
 

Yes, essentially. According to Elon the changes required are minor.

[RealKerbal3x]

 

[RCgothic]

Interesting shot of the damage.

 

Construction near the high bay.

Pad C? At the old oil well.

 

 

 

 

[RealKerbal3x]

7 hours ago, RCgothic said:

Pad C? At the old oil well.

Probably for a display stand of some kind, the accommodation for the workers is those trailers at the top of the image. They wouldn't put a test/launch stand there.

[AVaughan]

Just now, RealKerbal3x said:

Probably for a display stand of some kind

SN9, after its test flight.

Spoiler

Assuming it lands intact.

 

[kerbiloid]

Spoiler

A concrete slab with six pits to seal the starship legs to stop it from flying away.

After that case with "fins" which actually were a roof of cafe or something, I would expect something like the good old classics.
 

Spoiler

 

 

[Flying dutchman]

i tried my best to photoshop starship on the dam in amsterdam, shows you just how big it really is.

Edited December 26, 2020 by Flying dutchman

[kerbiloid]

It's another one to the right, with green nosecone.

Squared cross-section???

Edited December 26, 2020 by kerbiloid

[sh1pman]

8 hours ago, kerbiloid said:

It's another one to the right, with green nosecone.

Squared cross-section???

There’s also one in the background, with launch escape system installed.

[kerbiloid]

5 hours ago, sh1pman said:

There’s also one in the background, with launch escape system installed.

The right one is also equipped with nozzles around the head, like Crew Dragon.

Let me guess the name of this secret starship.

Spoiler

Den Vliegende Hollander

 

Spoiler

Also, looking at the right one, I see the source of inspiration of the designers of G11 shell.

 

Edited December 27, 2020 by kerbiloid

[RealKerbal3x]

Nice article on Earth to Earth travel, and awesome render: