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I wondered about that, too. After all, you would assume that all you would have to do is to burn the fuel-rich pre-burner exhaust with a oxygen-enriched mixture in the main chamber or vice versa.

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25 minutes ago, sevenperforce said:

The article wasn't entirely correct; from a fuel consumption standpoint, an ORSC or FRSC engine is just as efficient. However, the preburner must be oversized in order to run both oxygen and fuel turbopumps, and using the same driveshaft runs into seal issues. You also have mixture problems, and you can't run chamber pressure nearly as high as a FFSC because you're running split.

Makes sense now. Thanks

Ok I read about it a bit more, and it turns out that full gasification of fuel components in full flow scheme leads to more complete combustion in the c. chamber, which increases the specific impulse by 10-20s compared to regular single-preburner staged combustion scheme. So it is indeed more efficient.

Edited by sh1pman
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47 minutes ago, sh1pman said:

Makes sense now. Thanks

Ok I read about it a bit more, and it turns out that full gasification of fuel components in full flow scheme leads to more complete combustion in the c. chamber, which increases the specific impulse by 10-20s compared to regular single-preburner staged combustion scheme. So it is indeed more efficient.

Higher combustion completion and higher chamber pressures both increase net efficiency and Isp, but from a fuel consumption standpoint it's not like anything is getting dumped overboard in ORSC or FRSC (in comparison to GG or CCTO, where something IS getting dumped overboard or injected into the exhaust).

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4 minutes ago, sevenperforce said:

Higher combustion completion and higher chamber pressures both increase net efficiency and Isp, but from a fuel consumption standpoint it's not like anything is getting dumped overboard in ORSC or FRSC (in comparison to GG or CCTO, where something IS getting dumped overboard or injected into the exhaust).

Yes, I was originally asking about the efficiency advantage of full flow, not fuel consumption. Obviously, nothing gets dumped overboard in both cases.

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Not the simplest thing!

Raptor_Engine_Unofficial_Combustion_Sche

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1 hour ago, sh1pman said:

Not the simplest thing!

Raptor_Engine_Unofficial_Combustion_Sche

Still looks simpler than the Shuttle engine layout. 
Like how they put the oxidizer pump just on top of engine. 

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(that's the visitor)

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46 minutes ago, tater said:

 

Nice to see you over here on the East Coast, buddy.

22 hours ago, sh1pman said:

Not the simplest thing!

Raptor_Engine_Unofficial_Combustion_Sche

It's still hard for me to wrap my head around the idea of using hot gas to pump itself. I can think through it, of course, but still.

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52 minutes ago, sevenperforce said:

It's still hard for me to wrap my head around the idea of using hot gas to pump itself. I can think through it, of course, but still.

It's just a turbojet engine that takes in liquid and outputs supercritical fluid. Pretty straightforward operational theory, at least. *shrugs* Practical application of said theory, though... lol.gif

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23 hours ago, magnemoe said:

Still looks simpler than the Shuttle engine layout. 
Like how they put the oxidizer pump just on top of engine. 

Quick, cheap, dirty...

NK33.

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2 hours ago, sevenperforce said:

It's still hard for me to wrap my head around the idea of using hot gas to pump itself. I can think through it, of course, but still.

The turbo pumps are started by the starting system (various means to do this, not sure which one is used here) until the pump sides of both are now filled with fluid (the pumps are designed to drive liquids and need to stay wet to work properly) and both preburners (methane-rich to drive the LMG turbine and oxygen-rich to drive the LOX turbine) are going and taking over spinning the pumps.  Everything builds up to pressure and steady-state operation.

https://en.wikipedia.org/wiki/Staged_combustion_cycle

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1 hour ago, Xd the great said:

Quick, cheap, dirty...

NK33.

It works, you don't want to get into engine out. They are only funny on an B52 in level flight then you request priority landing because engine out :) 

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39 minutes ago, magnemoe said:

It works, you don't want to get into engine out. They are only funny on an B52 in level flight then you request priority landing because engine out :) 

The B-52 always has to land at the same IAS due to the fore and aft landing gears needing to touch down at the same time.  I think that's the source of that.

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3 hours ago, Xd the great said:

Quick, cheap, dirty...

NK33.

As I understand it, the main problem with the NK33 was quality of the build and/or materials

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1 hour ago, magnemoe said:

It works, you don't want to get into engine out. They are only funny on an B52 in level flight then you request priority landing because engine out :) 

Nah, the engine out thing is just a party trick.  As the old joke goes:

"An F-15 was flying escort with a B-52 and generally making a nuisance of himself by flying rolls around the lumbering old bomber. The F-15 pilot radioed the B-52: "How do you like that, eh?." Not to be outdone, the bomber pilot announced that he would rise to the challenge. The F-15 pilot dropped back and waited.  And waited.  And waited.  Nothing appeared to happen--the B-52 continued its flight, straight and level. Perplexed, the fighter pilot asked, "So? What did you do?"  "We just shut down three engines.  Beat that."

(In the last 5 minutes, I've seen this same joke refer the the hotshot pilot alternatively flying an F-14, an F-15, and an F-16)

Edited by zolotiyeruki
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42 minutes ago, zolotiyeruki said:

Nah, the engine out thing is just a party trick.  As the old joke goes:

"An F-15 was flying escort with a B-52 and generally making a nuisance of himself by flying rolls around the lumbering old bomber. The F-15 pilot radioed the B-52: "How do you like that, eh?." Not to be outdone, the bomber pilot announced that he would rise to the challenge. The F-15 pilot dropped back and waited.  And waited.  And waited.  Nothing appeared to happen--the B-52 continued its flight, straight and level. Perplexed, the fighter pilot asked, "So? What did you do?"  "We just shut down three engines.  Beat that."

(In the last 5 minutes, I've seen this same joke refer the the hotshot pilot alternatively flying an F-14, an F-15, and an F-16)

I've also seen it as  the B-52 pilot going back and either getting a cup of coffee... or using the restroom.

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3 hours ago, StrandedonEarth said:

As I understand it, the main problem with the NK33 was quality of the build and/or materials

NK-15. Quality of build was just one problem - most of the trouble was with fire safety, and the engine (not just the stage) was designed with zero refire capability, with pyrovalves and membranes. The good old Soviet approach of expending a large fraction of the engines produced in testing had to be called upon... a d it wasn’t enough.

By NK-33 most of this was rectified, and Sutton remarked that the production engines were remarkably decluterred compared to most he’d seen since working on Redstone.

3 hours ago, MaverickSawyer said:

I've also seen it as  the B-52 pilot going back and either getting a cup of coffee... or using the restroom.

How to make a Strike Eagle pilot die of envy

ACAH_Su-34_003.jpg

 

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2 hours ago, DDE said:

How to make a Strike Eagle pilot die of envy

Is that the one that has a little galley, latrine, and sleeping bunk in back?

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1 hour ago, CatastrophicFailure said:

Is that the one that has a little galley, latrine, and sleeping bunk in back?

From what I understand, the “bunk” is the floor (deck?). The middle console retracts to make room for someone to fully stretch their legs.

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2 hours ago, tater said:

 

I was confused because it looked stationary untill i saw the tracks. 

Would love to ride it

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1 hour ago, NSEP said:

I was confused because it looked stationary untill i saw the tracks. 

Would love to ride it

Why tracks, its running on an flat deck, that is unless they want to move the rocket with it.

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