Well it sounds interesting. I’m kind of skeptical about it though. I mean Blue Origin doesn’t have much of a development background on pumped-fed liquid propulsion and they just jump straight into doing a LOX-rich staged combustion LOX/Methane engine in the RD-191 class? Good luck.
I wish they succeed but I wouldn’t bet on it.
I am sure Blue Origin has hired several Propulsion Engineers with considerable experience.
Drats. I assumed it was just a regular LOX/Methane gas generator cycle engine when I first read about it. It seems Blue Origin does indeed state they are doing a LOX-rich staged combustion engine. IMO that just pushes it a bit further than the realm of the possible.
For a lot of people, including me, Blue Origin seems just like a side distraction or hobby to a gazzilionaire like Bezos. It’s not like Musk who basically changed his whole life just to be close to the company the whole time even to an unhealthy degree. He just did not invest nearly as much of his time in it. I think they just bit a lot more than they can chew.
Well, they claim to already have a subscale version of it.
Anything new on the ULA/XCor engine? I guess that would be a future iteration of the upper stage on this thing?
I’ll probably go up and see them next week. It’s XCOR, by the way.
Is there anything about this new engine that us common folk would call “next gen” or is it just a new line, or new generation, of launch vehicles for ULA?
It would be the first-ever staged-combustion lox-rich methane engine ever built. And it will probably be reusable.
Awesome, ty.
There is no native US designed staged combustion LOX/Hydrocarbon engine in use today. The only staged combustion engine design in the US that entered production was the Space Shuttle Main Engine and that AFAIK used a fuel-rich LOX/LH2 combustion cycle. The only country currently using this kind of technology, albeit with LOX/Kerosene, is Russia. It is a leading edge engine design. Assuming they can get it to work that is.
It seems kind of bonkers as a design to me though. The French had a collaboration with the Russians at one point but they intended to use a *fuel rich* LOX/Methane cycle. The difficulty of using LOX rich combustion, like the Russians do, is that it is very difficult to get the metallurgy right. LOX rich combustion is essential for LOX/Kerosene staged combustion cycles because it reduces coking and fouling that would otherwise clog up the engine. This is due to polymerization of the long chain hydrocarbons in Kerosene. LH2 does not have that problem so you can run it fuel-rich. Methane allegedly does not have the problem either but it probably depends on the formulation. Industrial methane aka ‘natural gas’ is not pure LCH4 and I am not aware of standards on this for rocket engines.
LOX rich staged combustion basically eats away metal. The Russians supposedly prevent this with special alloys and coatings in the RD-170 family of engines but it is still a mess to get it working correctly and supposedly was one of the things which were not 100% described when the technology transfer for the RD-180 was done.
Isn’t one of the advantages of fuel rich when burning hydrogen that you have a lower molecular weight exhaust and hence a slight boost in specific impulse, or maybe a boost in specific impulse relative to the oxygen-rich side of stoichiometric? Does this work for methane?
Not as much, and there are other factors to consider…
The mixture ratios for the turbo pump and for the main combustion chamber are two completely different things. You could run the engine fuel-rich but still have an oxygen-rich staged-combustion cycle: run all of the oxygen but only a little bit of the fuel through the turbine.
The Isp of lox-methane usually peaks a little bit fuel-ward from stoichiometric, but not nearly so far as does lox-hydrogen. The exact ratio will depend on chamber pressure and expansion ratio, but lox-methane would typically peak around a ratio of 3.5 as opposed to a stoichiometric ratio of 4. Of course, optimizing vehicle performance is not the same thing as optimizing Isp. Not only do fuel-rich mixtures usually have lower density, but they often produce lower thrust as well.
And in full-flow staged combustion, which is what SpaceX plans for its lox-methane engine (Raptor), there is one fuel-rich turbine and one oxygen-rich turbine.
I have no response, except to say that we will see.
Great, thanks.
So if I read your and Rand’s comments correctly, what makes this next gen is the fuel rich staged combustion, materials that allow for use of LNG or methane, and potential re-usability?
But that it wont be next gen in terms of performance, like ISP? Or, IIRC, is there a performance boost with this fuel in space?
Just trying to get a grip on how next gen this is supposed to be.
LOX/Methane will always have an Isp somewhere between LOX/LH2 and LOX/Kerosene. It’s just how it is. The actual Isp depends on engine chamber pressure and expansion ratio.
Another important factor is tankage weight as supposedly you can use a common bulkhead and store LOX and Methane at roughly the same temperature. Still because Methane is a lot less dense than Kerosene, the tanks will still be heavier than Kerosene tanks, although not as heavy as LH2 tanks.
Thanks, sorry for being lazy and not doing my own research 🙂
I didn’t see the word “reusable” in there.
I didn’t say the word was there. Nonetheless, I strongly suspect that it will be.
My comment wasn’t a reply to your 11.38 am comment.
I’m just saying that if they’re not reusable they’re already obsolete, like SLS.
One advantage to using a LOX/Methane engine: It fits in to a lot of ISRU plans out there – i.e. launch from Mars.
Well it sounds interesting. I’m kind of skeptical about it though. I mean Blue Origin doesn’t have much of a development background on pumped-fed liquid propulsion and they just jump straight into doing a LOX-rich staged combustion LOX/Methane engine in the RD-191 class? Good luck.
I wish they succeed but I wouldn’t bet on it.
I am sure Blue Origin has hired several Propulsion Engineers with considerable experience.
Drats. I assumed it was just a regular LOX/Methane gas generator cycle engine when I first read about it. It seems Blue Origin does indeed state they are doing a LOX-rich staged combustion engine. IMO that just pushes it a bit further than the realm of the possible.
For a lot of people, including me, Blue Origin seems just like a side distraction or hobby to a gazzilionaire like Bezos. It’s not like Musk who basically changed his whole life just to be close to the company the whole time even to an unhealthy degree. He just did not invest nearly as much of his time in it. I think they just bit a lot more than they can chew.
Well, they claim to already have a subscale version of it.
Anything new on the ULA/XCor engine? I guess that would be a future iteration of the upper stage on this thing?
I’ll probably go up and see them next week. It’s XCOR, by the way.
Is there anything about this new engine that us common folk would call “next gen” or is it just a new line, or new generation, of launch vehicles for ULA?
It would be the first-ever staged-combustion lox-rich methane engine ever built. And it will probably be reusable.
Awesome, ty.
There is no native US designed staged combustion LOX/Hydrocarbon engine in use today. The only staged combustion engine design in the US that entered production was the Space Shuttle Main Engine and that AFAIK used a fuel-rich LOX/LH2 combustion cycle. The only country currently using this kind of technology, albeit with LOX/Kerosene, is Russia. It is a leading edge engine design. Assuming they can get it to work that is.
It seems kind of bonkers as a design to me though. The French had a collaboration with the Russians at one point but they intended to use a *fuel rich* LOX/Methane cycle. The difficulty of using LOX rich combustion, like the Russians do, is that it is very difficult to get the metallurgy right. LOX rich combustion is essential for LOX/Kerosene staged combustion cycles because it reduces coking and fouling that would otherwise clog up the engine. This is due to polymerization of the long chain hydrocarbons in Kerosene. LH2 does not have that problem so you can run it fuel-rich. Methane allegedly does not have the problem either but it probably depends on the formulation. Industrial methane aka ‘natural gas’ is not pure LCH4 and I am not aware of standards on this for rocket engines.
LOX rich staged combustion basically eats away metal. The Russians supposedly prevent this with special alloys and coatings in the RD-170 family of engines but it is still a mess to get it working correctly and supposedly was one of the things which were not 100% described when the technology transfer for the RD-180 was done.
Isn’t one of the advantages of fuel rich when burning hydrogen that you have a lower molecular weight exhaust and hence a slight boost in specific impulse, or maybe a boost in specific impulse relative to the oxygen-rich side of stoichiometric? Does this work for methane?
Not as much, and there are other factors to consider…
The mixture ratios for the turbo pump and for the main combustion chamber are two completely different things. You could run the engine fuel-rich but still have an oxygen-rich staged-combustion cycle: run all of the oxygen but only a little bit of the fuel through the turbine.
The Isp of lox-methane usually peaks a little bit fuel-ward from stoichiometric, but not nearly so far as does lox-hydrogen. The exact ratio will depend on chamber pressure and expansion ratio, but lox-methane would typically peak around a ratio of 3.5 as opposed to a stoichiometric ratio of 4. Of course, optimizing vehicle performance is not the same thing as optimizing Isp. Not only do fuel-rich mixtures usually have lower density, but they often produce lower thrust as well.
And in full-flow staged combustion, which is what SpaceX plans for its lox-methane engine (Raptor), there is one fuel-rich turbine and one oxygen-rich turbine.
I have no response, except to say that we will see.
Great, thanks.
So if I read your and Rand’s comments correctly, what makes this next gen is the fuel rich staged combustion, materials that allow for use of LNG or methane, and potential re-usability?
But that it wont be next gen in terms of performance, like ISP? Or, IIRC, is there a performance boost with this fuel in space?
Just trying to get a grip on how next gen this is supposed to be.
LOX/Methane will always have an Isp somewhere between LOX/LH2 and LOX/Kerosene. It’s just how it is. The actual Isp depends on engine chamber pressure and expansion ratio.
Another important factor is tankage weight as supposedly you can use a common bulkhead and store LOX and Methane at roughly the same temperature. Still because Methane is a lot less dense than Kerosene, the tanks will still be heavier than Kerosene tanks, although not as heavy as LH2 tanks.
Thanks, sorry for being lazy and not doing my own research 🙂
I didn’t see the word “reusable” in there.
I didn’t say the word was there. Nonetheless, I strongly suspect that it will be.
My comment wasn’t a reply to your 11.38 am comment.
I’m just saying that if they’re not reusable they’re already obsolete, like SLS.
One advantage to using a LOX/Methane engine: It fits in to a lot of ISRU plans out there – i.e. launch from Mars.