Wiki Super Heavy/Starship - General Development Discussion

[JB47394]

I believe the mishap report analysis that SpaceX submits to the FAA for the launch license is public

I believe that anything considered proprietary to their business would not be made public. Given the business, that could be pretty much anything. Fortunately, SpaceX is normally quite forthcoming with information. I know I'm hungry for details. I can be amused by the destruction of water tanks for only so long.

I hope we'll get some insight as to the issues that caused both the Booster and Starship to explode...

A guy on the web was observing that Starship didn't have any cargo, so it was particularly light. That means that SpaceX would want to keep the engine thrust down, especially towards the latter part of the flight, when it was at its lightest. They could throttle back and/or shut off engines. They don't have any experience with running the engines in vacuum, so perhaps the low throttling and/or shut off in vacuum caused a problem.

In truth, they didn't have any experience with operating a Starship in that regime, so I guess it could be a lot of things.

 

[scaesare]

Agreed.... is a unlike them/Elon.

 

[ecarfan]

A guy on the web was observing that Starship didn't have any cargo, so it was particularly light.

If IFT-2 had included a really big wheel of cheese I’m sure it would have made it to orbit!

 

[GWord]

If IFT-2 had included a really big wheel of cheese I’m sure it would have made it to orbit!

Not enough towels.

 

[ICUDoc]

If IFT-2 had included a really big wheel of cheese I’m sure it would have made it to orbit!

More Roadster ballast?

 

[scaesare]

I believe that anything considered proprietary to their business would not be made public. Given the business, that could be pretty much anything. Fortunately, SpaceX is normally quite forthcoming with information. I know I'm hungry for details. I can be amused by the destruction of water tanks for only so long.


A guy on the web was observing that Starship didn't have any cargo, so it was particularly light. That means that SpaceX would want to keep the engine thrust down, especially towards the latter part of the flight, when it was at its lightest. They could throttle back and/or shut off engines. They don't have any experience with running the engines in vacuum, so perhaps the low throttling and/or shut off in vacuum caused a problem.

In truth, they didn't have any experience with operating a Starship in that regime, so I guess it could be a lot of things.

Given they were up in very thin atmosphere at that point, is the assumption that they'd want to limit acceleration in order to manage g-force loading of the ship structure?

As for the engines, I believe the primary difference is the nozzle, right? Are there typically any other real engine differences in a vacuum optimized rocket engine, or is that really more of a tank/plumbing concern?

 

[JB47394]

Given they were up in very thin atmosphere at that point, is the assumption that they'd want to limit acceleration in order to manage g-force loading of the ship structure?

Yes. They'd approach 15g by the time the tanks were dry. 1,500 tons thrust on a 100 ton vehicle without payload.

As for the engines, I believe the primary difference is the nozzle, right?

Right. I know of no other changes needed for efficiency in vacuum.

 

[ecarfan]

The process of tearing down tent #3 is almost complete, B12 cryo tested at Masseys, S28 lifted onto engine installation stand, lots of ships being moved around!

So many Starships! But what is going to happen to S26? It seems to have been passed over. Was it just a test article? Will it ever fly? And what about S20?

This is interesting. Instead of relying entirely on local water supplies, they are going to produce liquid water directly from the air.

 

[mongo]

This is interesting. Instead of relying entirely on local water supplies, they are going to produce liquid water directly from the air.
View attachment 1008819

Those are to use air to vaporize liquid CH4 and LOX for storage tank ullage instead of using water based heat exchangers. Nothing to do with generating water.

Tesla does similar thing for Nitrogen supply.

 

[ecarfan]

Those are to use air to vaporize liquid CH4 and LOX for storage tank ullage instead of using water based heat exchangers.

Thanks, I did not realize that. Here is a company that makes ambient air vaporizers and here is a basic explanation.

 

[Buckminster]

https://twiiter.com/FelixSchlang/status/1747342807168410039?s=20

 

[JB47394]

https://twiiter.com/FelixSchlang/status/1747342807168410039?s=20

"We've got a version three ship design that will stretch that [to] be even taller, probably end up being, I don't know, 140 meters before it's all said and done - maybe 150 in the end."

The image is showing a 150 meter tall rocket, and all the volume has gone to propellant tanks.

Another Bonkers By Elon™ statement:

"We've got a whole development plan to [...] ultimately get to a fully reusable rocket that does over 200 tons to orbit on a regular basis."

As a point of comparison, the Saturn V was expended and could loft 141 tons to LEO. Or we could just say that it's almost eleven Falcon 9 launches.

 

[Buckminster]

"We've got a version three ship design that will stretch that [to] be even taller, probably end up being, I don't know, 140 meters before it's all said and done - maybe 150 in the end."

The image is showing a 150 meter tall rocket, and all the volume has gone to propellant tanks.

Another Bonkers By Elon™ statement:

"We've got a whole development plan to [...] ultimately get to a fully reusable rocket that does over 200 tons to orbit on a regular basis."

As a point of comparison, the Saturn V was expended and could loft 141 tons to LEO. Or we could just say that it's almost eleven Falcon 9 launches.

What are you disputing?

 

[JB47394]

What are you disputing?

Is that required?

 

[Buckminster]

Is that required?

You would rather they go straight to next gen?

https://twitter.com/x/status/1166856662336102401

 

[ecarfan]

[Elon] "We've got a version three ship design that will stretch that [to] be even taller, probably end up being, I don't know, 140 meters before it's all said and done - maybe 150 in the end."

I wonder if the existing tower at Boca can have enough additional height added to it to accommodate that?

And I thought that currently available cranes can’t be used for structures that tall?

 

[JB47394]

You would rather they go straight to next gen?

They might want to get their current hardware working first.

I wonder if the existing tower at Boca can have enough additional height added to it to accommodate that?

And I thought that currently available cranes can’t be used for structures that tall?

Just assume that the Starship is stretched to match the booster's tank volume. Now you have a 70-80m Starship sitting on a 70 meter booster. Leave the lift points on the Starship at 40 meters from the bottom, and everything works. Starship would be top heavy during a lift, so that would have to be addressed.

Interestingly, when SpaceX built the new megabay for Starships, they built it to the same dimensions as the booster megabay. So they're already set for stretched Starships. Meanwhile, if they want to stretch a booster, they've gotta increase the height of that megabay. It would also require moving the ship quick disconnect, and figuring out how to get the chopsticks to reach higher during stacking operations. It may be possible to address that without increasing the height of the tower. I'm pretty sure we've talked about this before.

To understand how a stretched Starship reaches orbit, here's that video that a guy put together that shows the trajectory (more or less; read the comments). I posted it once before. The author covers two cases according to the division of propellant mass between booster and ship. The left rocket is 1:1 and the right is 2:1. The current Starship is about 3:1. If you watch the left rocket, the booster stages very quickly, then the Starship actually dips to a lower altitude than it was at staging. That's because its thrust:weight ratio remains too low until it has used some of its propellant.

 

[scaesare]

You would rather they go straight to next gen?

https://twitter.com/x/status/1166856662336102401

Wow... Elon going for length this go-round, and girth the next...

 

[scaesare]

Is that required?

Maybe just typical, and therefore assumed?

 

[ecarfan]

Wow... Elon going for length this go-round, and girth the next...

18m diameter? I think that is at least a decade away.