totm nov 2023 SpaceX Discussion Thread

[Beccab]

25 minutes ago, JoeSchmuckatelli said:

The drawing of BN2 shows a boatload of Raptors sketched for future hanging 

How many would they actually need for suborbital testing?  Is 3 enough?  6?

On the top of the 29 tater mentioned (used in the first orbital flight, as BN2 won't make hops) Superheavy will later grow to 32 raptors by replacing the middle lone raptor with four

[tater]

12 minutes ago, Beccab said:

On the top of the 29 tater mentioned (used in the first orbital flight, as BN2 won't make hops) Superheavy will later grow to 32 raptors by replacing the middle lone raptor with four

I suppose in a certain sense SH will only ever make suborbital hops

 

[Elthy]

Also the bottom of Superheavy has to withstand the reentry heat on every flight, from what i know without any active cooling. So propably the engines and surrounding sturcutres can take way more heat than other rockets.

[tater]

1 minute ago, Elthy said:

Also the bottom of Superheavy has to withstand the reentry heat on every flight, from what i know without any active cooling. So propably the engines and surrounding sturcutres can take way more heat than other rockets.

The engines are regeneratively cooled, however.

What we have not yet seen is what any oktokaieikosi-web (LOL) will look like (they use octoweb for 9 engines, so I assumed n-1 for SH). Presumably they have some thermal protection they will add tothe bottom assuming a similar flight path—that or they enter sideways, since I think they said no entry burn.

[Beccab]

Just now, tater said:

(they use octoweb for 9 engines, so I assumed n-1 for SH)

I believe the number is based on the number of engines on the outer ring

[tater]

Just now, Beccab said:

I believe the number is based on the number of engines on the outer ring

So icosaweb in this case.

[RCgothic]

Or dodecaweb.

[NFUN]

31 minutes ago, RCgothic said:

Or dodecaweb.

nerds

[kurja]

4 hours ago, NFUN said:

nerds

You expected anything else? 

[magnemoe]

5 hours ago, tater said:

The engines are regeneratively cooled, however.

What we have not yet seen is what any oktokaieikosi-web (LOL) will look like (they use octoweb for 9 engines, so I assumed n-1 for SH). Presumably they have some thermal protection they will add tothe bottom assuming a similar flight path—that or they enter sideways, since I think they said no entry burn.

Engines are regenerated cooled on the way up, not down but bells can handle plenty of heat, you need to protect the upper parts however as they contains plenty of valves and sensors who don't handle heat as well. You could make an short skirt and an deck at the start of the nozzles, look at an electron rocket bottom for how this would work. 
An full skirt like starship would also protect the engines well. Unlike starship skirt is not load bearing just thermal protection. 
 

[tater]

36 minutes ago, magnemoe said:

Engines are regenerated cooled on the way up, not down but bells can handle plenty of heat, you need to protect the upper parts however as they contains plenty of valves and sensors who don't handle heat as well. You could make an short skirt and an deck at the start of the nozzles, look at an electron rocket bottom for how this would work. 
An full skirt like starship would also protect the engines well. Unlike starship skirt is not load bearing just thermal protection. 
 

They're cooled while running, and yes, that is not the case for the bulk of entry (or indeed most of the engines that only fire on ascent).

Gotta wonder about the skirt, but the one part of all this that they know a LOT about is what happens to engines exposed to 2.x km/s entry velocities.

[JoeSchmuckatelli]

7 hours ago, Beccab said:

On the top of the 29 tater mentioned (used in the first orbital flight, as BN2 won't make hops) Superheavy will later grow to 32 raptors by replacing the middle lone raptor with four

Wait - their first attempt with SH will be orbital? 

 

That means they'll need a SS to go along for the ride 

[cubinator]

Just now, JoeSchmuckatelli said:

That means they'll need a SS to go along for the ride 

that would be SN20.

[JoeSchmuckatelli]

1 hour ago, cubinator said:

that would be SN20.

Yeah - I expect that now... for whatever reason I thought they'd build a SH and we'd see a repeat of SN-analogous launches to practice landing, rather than a full flight attempt (3/4 around the planet counts, I would think).

Impressively bold.

So... now I'm confused.  What ship is going to do a practice landing (but actually ditch) into the water near Hawaii -- Is that SN20?  If so, what will SH do?  Practice land in the Atlantic?

[OrdinaryKerman]

2 hours ago, JoeSchmuckatelli said:

Yeah - I expect that now... for whatever reason I thought they'd build a SH and we'd see a repeat of SN-analogous launches to practice landing, rather than a full flight attempt (3/4 around the planet counts, I would think).

Impressively bold.

So... now I'm confused.  What ship is going to do a practice landing (but actually ditch) into the water near Hawaii -- Is that SN20?  If so, what will SH do?  Practice land in the Atlantic?

Yes, that's SN20. IIRC Booster 2 will do a boostback burn and soft-landsplash in the somewhere Gulf of Mexico.

Edited June 20, 2021 by OrdinaryKerman

[Nothalogh]

2 hours ago, JoeSchmuckatelli said:

Impressively bold.

Go big, or go home

[JoeSchmuckatelli]

2 hours ago, Nothalogh said:

Go big, or go home

IKR?!!

[CatastrophicFailure]

2 hours ago, Nothalogh said:

Go big, or go home

[Beccab]

23 minutes ago, CatastrophicFailure said:

B-but those are SRBs you can't do that

[CatastrophicFailure]

37 minutes ago, Beccab said:

B-but those are SRBs you can't do that

Life Elon, uh, finds a way… 

[tater]

GPS-III booster landing:

 

[Beccab]

6 minutes ago, tater said:

GPS-III booster landing:

 

Beautiful!
Also:

 

[tater]

3 minutes ago, Beccab said:

Also:

So either taller, or more than 1 pad.

[Beccab]

Just now, tater said:

So either taller, or more than 1 pad.

I believe it's just the crane mount stuff (which was considered separate from normal section) seeing how it's much shorter and has a different endcap

[RCgothic]

Taller, I reckon. The 2nd pad is nowhere near ready to start construction, and if the 22m payload fairing starship variant in the Starship User Guide is actually ever going to be a thing it'll need more than minimal tower clearance on the standard 18m fairing Starship version.