Author Topic: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion  (Read 1040083 times)

Offline Herb Schaltegger

Just throwing in a quick note: Pad B is NOT clear, so no static fire testing from S24 today.

When making a statement like that, please specify: is this a definitive word from SpaceX of just commentary/supposition? The window goes until 10:00pm and could potentially be extended.
« Last Edit: 08/11/2022 06:06 pm by Herb Schaltegger »
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Offline alugobi

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2321 on: 08/11/2022 06:25 pm »
If Pad B isn't clear, then they aren't going to be firing the booster, either.

Offline alugobi

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2322 on: 08/11/2022 07:20 pm »
Why were there no frost/condensation lines on the booster for it's firing yesterday?

Wait, I think I know the answer.  Because the outer ring of engines is serviced by the OLM for startup.  So there's enough fuel and oxidizer there for a static fire.  No need to fill the booster tanks. 

Is that right?
« Last Edit: 08/11/2022 07:23 pm by alugobi »

Offline Slothman

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2323 on: 08/11/2022 07:24 pm »
Why were there no frost/condensation lines on the booster for it's firing yesterday?

They're only there when the fill level of the tank is above the bottom dome. Think about a gkass of iced lemonade in summer, the condensation on the outside only goes to the liquid level.

Offline Herb Schaltegger

So the word has been that all the outer engines startup using GSE-supplied fluids. However, obviously there has to be a transition to vehicle-supplied propellants pretty darn quick as the vehicle lifts off.  Today's longer 21 second test is interesting because Elon specifically tweeted that it was a test of autogenous pressurization - which means that after startup, it had to transition cleanly to internal tanks, which then maintained internal tank pressure throughout.
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Offline Lee Jay

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2325 on: 08/11/2022 08:47 pm »
So the word has been that all the outer engines startup using GSE-supplied fluids. However, obviously there has to be a transition to vehicle-supplied propellants pretty darn quick as the vehicle lifts off.

It's possible that I'm lost, but "GSE-supplied fluids" to me means nitrogen, helium (whatever) for spin-up and other start neads but they always run on vehicle-supplied propellants.

Online rsdavis9

So the word has been that all the outer engines startup using GSE-supplied fluids. However, obviously there has to be a transition to vehicle-supplied propellants pretty darn quick as the vehicle lifts off.

It's possible that I'm lost, but "GSE-supplied fluids" to me means nitrogen, helium (whatever) for spin-up and other start neads but they always run on vehicle-supplied propellants.

I am not an authority. But I believe startup gases and electric from engine QD makes the most sense. Liquid from tank.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
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Offline Khadgars

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2327 on: 08/11/2022 08:54 pm »
How many Raptors are they firing in these recent static fires of B7?  Looks like a single engine?
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Online meekGee

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2328 on: 08/11/2022 09:01 pm »
So the word has been that all the outer engines startup using GSE-supplied fluids. However, obviously there has to be a transition to vehicle-supplied propellants pretty darn quick as the vehicle lifts off.

It's possible that I'm lost, but "GSE-supplied fluids" to me means nitrogen, helium (whatever) for spin-up and other start neads but they always run on vehicle-supplied propellants.

Yes agreed
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Offline StevenOBrien

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2329 on: 08/11/2022 09:02 pm »
How many Raptors are they firing in these recent static fires of B7?  Looks like a single engine?
Single engine on Tuesday.

Based on all the views I've looked at of today's long-duration static fire, it looks like another single engine firing (though, a different engine, on the opposite side). No official confirmation yet.

Offline wannamoonbase

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2330 on: 08/11/2022 09:05 pm »
So the word has been that all the outer engines startup using GSE-supplied fluids. However, obviously there has to be a transition to vehicle-supplied propellants pretty darn quick as the vehicle lifts off.  Today's longer 21 second test is interesting because Elon specifically tweeted that it was a test of autogenous pressurization - which means that after startup, it had to transition cleanly to internal tanks, which then maintained internal tank pressure throughout.

I was thinking of that too.  21 seconds was long enough to start, transition and verify stable operation.  This was a single engine but a big test. 

If the data is good they can start adding more engines.

I'm so excited that we are finally at static fires for the booster.  Who knows how many more we will see, two, three, six or twelve.  We're tantalizing close to launch commit.
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Offline alugobi

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2331 on: 08/11/2022 09:49 pm »
Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

Offline russianhalo117

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2332 on: 08/11/2022 09:56 pm »
Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 
For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.
« Last Edit: 08/11/2022 09:56 pm by russianhalo117 »

Offline InterestedEngineer

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2333 on: 08/11/2022 10:59 pm »
Today's longer 21 second test is interesting because Elon specifically tweeted that it was a test of autogenous pressurization - which means that after startup, it had to transition cleanly to internal tanks, which then maintained internal tank pressure throughout.

Odd, I would have thought they'd not bother with autogenous feeds from the rim engines, only the center engines, to keep the plumbing simpler

Offline Vettedrmr

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2334 on: 08/11/2022 11:13 pm »
Anyone know why they didn't use the water deluge?  At least I didn't see evidence of it.
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Offline alugobi

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2335 on: 08/11/2022 11:22 pm »
Odd, I would have thought they'd not bother with autogenous feeds from the rim engines, only the center engines, to keep the plumbing simpler
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Offline russianhalo117

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2336 on: 08/11/2022 11:28 pm »
Anyone know why they didn't use the water deluge?  At least I didn't see evidence of it.
What they call water deluge is more consistent when compared with other domestic and international launch complexes with launch abort and pad fire suppression system given nozzles have horizontal and diagonally upwards facing high pressure nozzles. Water deluge and sound suppression systems generally use a different design using high flow rate rainbird nozzles (similar concept used in organ pipe slit design) in addition to a high concentration ratio of nozzles. The latter two systems do kot physically appear to be present whereas the fire suppression system seems to have a reasonable number of nozzles present.

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2337 on: 08/11/2022 11:31 pm »
With autogenous pressurization, there are heat exchangers on the hot parts of the engine to boiloff and heat propellant to use for pressurant. You could simplify things I suppose by only putting that plumbing on some of the engines, but not all of them.
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Offline xvel

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2338 on: 08/11/2022 11:33 pm »
Today's longer 21 second test is interesting because Elon specifically tweeted that it was a test of autogenous pressurization - which means that after startup, it had to transition cleanly to internal tanks, which then maintained internal tank pressure throughout.

Odd, I would have thought they'd not bother with autogenous feeds from the rim engines, only the center engines, to keep the plumbing simpler

Or maybe its simpler when each engine is always responsible for replacing only propellant it consumes with hot gases?
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Offline Vettedrmr

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Re: SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion
« Reply #2339 on: 08/11/2022 11:36 pm »
Anyone know why they didn't use the water deluge?  At least I didn't see evidence of it.
What they call water deluge is more consistent when compared with other domestic and international launch complexes with launch abort and pad fire suppression system given nozzles have horizontal and diagonally upwards facing high pressure nozzles. Water deluge and sound suppression systems generally use a different design using high flow rate rainbird nozzles (similar concept used in organ pipe slit design) in addition to a high concentration ratio of nozzles. The latter two systems do kot physically appear to be present whereas the fire suppression system seems to have a reasonable number of nozzles present.

Agree.  And I went back and watched the video, and they used their suppression system on S24, not B7's SF.  Although I still don't know why they either don't have or haven't used anything under the OLM.
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