SpaceX Raptor LRE Proposed Successor: Project LEET-1337 LRE

[Zed_Noir]

Wonder if the LEET-1337 will be developed as vacuum optimized engines for upgrading the Starship variants that goes beyond cisLunarspace later on?

Of course at least 16% better performance than the version that is written in the Issacson bio of Elon. 

[OTV Booster]

I was going to be a snarky little whatever and point out the acronyms thread: https://forum.nasaspaceflight.com/index.php?topic=34802.0
But then I noticed that it doesn’t include that particular one.  And, unfortunately, I’m as in the dark as you are.

I gave up on that a long time ago.

[Sarigolepas]

Why not something like this with film-cooled turbine blades?
I made this for laugh, but I'm serious xD

[meekGee]

Why not something like this with film-cooled turbine blades?
I made this for laugh, but I'm serious xD

The turbine in the main exhaust?

Rn it's at the exit of the pre burners, which is like a percent (well, some small fraction) of the total output.  I am not sure you can keep a turbine alive in the MCC.

[Sarigolepas]

Why not something like this with film-cooled turbine blades?
I made this for laugh, but I'm serious xD

The turbine in the main exhaust?

Rn it's at the exit of the pre burners, which is like a percent (well, some small fraction) of the total output.  I am not sure you can keep a turbine alive in the MCC.

I know, but this is the only cycle I can think of that could beat full flow.
Musk said that the engine that would make life multiplanetary would not be called raptor, implying it would have a different combustion cycle. And this is the only cycle left before we reach the physical limit in chamber pressure.

[meekGee]

Why not something like this with film-cooled turbine blades?
I made this for laugh, but I'm serious xD

The turbine in the main exhaust?

Rn it's at the exit of the pre burners, which is like a percent (well, some small fraction) of the total output.  I am not sure you can keep a turbine alive in the MCC.

I know, but this is the only cycle I can think of that could beat full flow.
Musk said that the engine that would make life multiplanetary would not be called raptor, implying it would have a different combustion cycle. And this is the only cycle left before we reach the physical limit in chamber pressure.

Playing along, the turbine will have lower pressure but higher temperature working fluid. (Two bada)  Not O2 rich. (Good).  A number of seals (bad).  Way too much power (bad) amf not really throttleable.

I think it's a bad trade, and is also something the first rocket builders looked at before going with power packs.

But you're right that this is Musk amd they will look at anything that doesn't violate the laws of physics, even if it's been looked at before.

[DJPledger]

Perhaps Raptor successor will be a RDRE which should give better performance than FFSC.

[Crispy]

Perhaps Raptor successor will be a RDRE which should give better performance than FFSC.

I've been having trouble pinning this down with google. Are we talking better thrust? ISP? T:W? And by how much?

[Robotbeat]

Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

[Sarigolepas]

Playing along, the turbine will have lower pressure but higher temperature working fluid. (Two bada)  Not O2 rich. (Good).  A number of seals (bad).  Way too much power (bad) amf not really throttleable.

I think it's a bad trade, and is also something the first rocket builders looked at before going with power packs.

But you're right that this is Musk amd they will look at anything that doesn't violate the laws of physics, even if it's been looked at before.

The pressure is indeed lower in the main combustion chamber than the preburner, but if you put the turbine between the combustion chamber and the nozzle you have more power available to drive the turbine, which increases chamber pressure, in this case it could be as high as 2000 bar since the temperature is 4 times higher.

It's actually counterintuitive, more heat means more power which means more pressure, so the density of the gases is the only thing that is constant.
Which makes sense because there must be an ideal expansion ratio of the gases inside the combustion chamber.

[meekGee]

Playing along, the turbine will have lower pressure but higher temperature working fluid. (Two bada)  Not O2 rich. (Good).  A number of seals (bad).  Way too much power (bad) amf not really throttleable.

I think it's a bad trade, and is also something the first rocket builders looked at before going with power packs.

But you're right that this is Musk amd they will look at anything that doesn't violate the laws of physics, even if it's been looked at before.

The pressure is indeed lower in the main combustion chamber than the preburner, but if you put the turbine between the combustion chamber and the nozzle you have more power available to drive the turbine, which increases chamber pressure, in this case it could be as high as 2000 bar since the temperature is 4 times higher.

It's actually counterintuitive, more heat means more power which means more pressure, so the density of the gases is the only thing that is constant.
Which makes sense because there must be an ideal expansion ratio of the gases inside the combustion chamber.

I think pressure out of the pre burners should be higher than the MC chamber...   Only a fraction of the flow, but higher pressure.

And it's a lot easier to extract work from high pressure and low temperature fluid than from low pressure high temperature fluid.

[RobLynn]

Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

Detonation destroys metals - the combination of extreme pressure fluctuations and ultra high temperatures penetrates normal boundary layers exposing surface of metals to destructive thermal spikes and pressure forces that are normally buffered by protective boundary layers.  This breaks down metal surfaces, stripping oxide protections and wrecks cavitating water pumps, water turbines, items left too long in sound nodes of ultrasonic baths, engine pistons + rings and other combustion chamber elements etc.  I strongly doubt that RDE's will ever be more than lab curiosities - much as they have been (in the form of variant pressure gain combustors) for 60 years.

[InterestedEngineer]

Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

The detonation velocity of methalox is about half the exhaust velocity of a Raptor.

[redneck]

Why not something like this with film-cooled turbine blades?
I made this for laugh, but I'm serious xD

Or taking it to the next level, regenerative cooled turbine blades in which the liquid flow through the blades is the last pump stage.

[warp99]

Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

The detonation velocity of methalox is about half the exhaust velocity of a Raptor.

An RDE engine has the detonation wave front circling at right angles to the exhaust flow so the detonation speed is not a limit on the exhaust velocity.  What is an issue is that a nozzle does not provide a significant gain in Isp as the collimation of the exhaust is set by the slot geometry.

[edzieba]

Rotating detonation engines are over-rated. None of them have demonstrated even mediocre performance, yet.

The detonation is just another way of trying to get a higher effective combustion pressure. A good pump system is at least as viable.

The point of RDREs is not increased efficiency or performance: turbomachinery-pumped engines can already get pretty close to the theoretical limits there. The point of an  RDRE is to achieve the same combustion pressures and temperatures without the turbomachinery, giving you an engine with the mechanical complexity and (similar) mass of a pressure-fed engine but the performance of a turbopump engine. Improved TWR with fewer moving parts.

[rsdavis9]

I was going to be a snarky little whatever and point out the acronyms thread: https://forum.nasaspaceflight.com/index.php?topic=34802.0
But then I noticed that it doesn’t include that particular one.  And, unfortunately, I’m as in the dark as you are.

I gave up on that a long time ago.

As long as we are on the subject: What does LRE stand for? Long Range Engine?

[niwax]

I was going to be a snarky little whatever and point out the acronyms thread: https://forum.nasaspaceflight.com/index.php?topic=34802.0
But then I noticed that it doesn’t include that particular one.  And, unfortunately, I’m as in the dark as you are.

I gave up on that a long time ago.

As long as we are on the subject: What does LRE stand for? Long Range Engine?

Liquid rocket engine. As opposed to SRB.

[rsdavis9]

So cross post from impulse thread.

ORSC targeting ~375s. Gotta love it when a propulsion engineer like Mueller talks about the trades with a degree of depth. Duration is also brought up; they already have to have a reasonable amount of insulation given that they're launching inside a fairing, but was only thinking a couple days maybe.

Engine cycle discussion at this timestamp
https://www.youtube.com/live/pojbt_bsafo?si=-ChW40dcx0dEs9c5&t=3482

So the deneb engine that impulse and mueller built is ORSC(oxygen rich staged combustion) and he talks why the raptor is FFSC(from sea level) and his engine is ORSC(in space).

[rsdavis9]

Also I really like impulse space's RCS system. Using the Saiph thruster.
The low toxicity of their N2O and Ethane is no laughing matter.
I think they are storing gas for these engines but I am not sure.