Rotating Detonation Engines

exclaimedleech8 said:
What sort of new capabilities could rotating detonation engines endow missiles? Could we get missiles with intercontinental range but small and light enough to be carried by a fighter jet?
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No. Around 30% more range with newer "standard" A2A missiles now roughly getting to 300 km that's another 100 km added. Even 10% is worth it. Examples being the pletora of intercepter systems lavered in ~20km range increments.
 
Seragina said:
No. Around 30% more range with newer "standard" A2A missiles now roughly getting to 300 km that's another 100 km added. Even 10% is worth it. Examples being the pletora of intercepter systems lavered in ~20km range increments.
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When you're talking about a ballistic missile, though, an RDE is a much bigger leap in efficiency over a rocket. And everything compounds. If the missile is light enough to be carried on an S/VTOL aircraft, then the plane can carry the missile high up in the sky where the air is much thinner, saving more fuel and more weight.
 
It's also possible to make turboshaft power from rotating detonation engines, could be ideal for powering tanks and land transports
 
Dagger said:
No, Raptor is NOT gas-gas, but LNG - LOX . What happens inside the "black box" is irrelevant.

Raptor converts LNG and LOX into exhaust. Both have a lower enthalpy than gaseous methane and gaseous hydrogen so the exhaust will also have less energy and therefor a lower Isp.
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Wrong, Raptor IS gas-gas. The statement is about the state of the propellants going into the combustion chamber and not the type of propellants.
 
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Detonation has overall more pressure.
 
RD-270 is about the only engine similar to Raptor, at least scale wise...outside of Stoke's first stage.
 
Any relevant reputable/verifiable website would be of help in this discussion, my kind Ladies and Sirs. Links have been proffered above, but please provide evidence why they are credible. Otherwise, please stay at least ten paces apart from each other...
 
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exclaimedleech8 said:
What sort of new capabilities could rotating detonation engines endow missiles? Could we get missiles with intercontinental range but small and light enough to be carried by a fighter jet?
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What is a missile? There are many contradictions in the use of the term rockets and missiles in the English language. It seams every kind of fast suicide drone is called missile, independent from the propulsion system (Tomahawk, Flamingo....). In German, we have the clear distinction between "Marschflugkörper" like the Tomahwak or Flamingo and rockets (like the Saturn V).
 
How does Magic Spacex Trungles arise in a thread about rotating detonation engines anybleepingway!???!?? This forum used to be Better.
 
Just a reminder : This forum and the posts, here and in other threads, are for all users ! If somebody wants to have a private discussion with just one person, PM or email is the means of choice !
 
Byeman said:
Wrong, Raptor IS gas-gas. The statement is about the state of the propellants going into the combustion chamber and not the type of propellants.
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This is clearly wrong when we are regarding the max ISP. Gas gas has higher values because you don't need to take away the evaporation heat from the reaction heat. In the Raptor engine (like in all standart liquid liquid rockets), the evaporation heat is taken out from the burned gassed (by cooling the nozzel). The total usable energy is therefor limited to liquid/liquid and not gas/gas.
 
Nicknick said:
This is clearly wrong when we are regarding the max ISP. Gas gas has higher values because you don't need to take away the evaporation heat from the reaction heat. In the Raptor engine (like in all standart liquid liquid rockets), the evaporation heat is taken out from the burned gassed (by cooling the nozzel). The total usable energy is therefor limited to liquid/liquid and not gas/gas.
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The term has nothing to do with ISP. It is about the type of engines. Just like ram-jet, turbo jet, fan jet are descriptors for jet engines,
 

Looking at the condensation on the engine it makes me wonder what they're using for propellant. I was hoping air/kerosene but it looks like cryo.
 
Byeman said:
The term has nothing to do with ISP. It is about the type of engines. Just like ram-jet, turbo jet, fan jet are descriptors for jet engines,
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Of course it has. The ISP depends on the amount of availablr energy and the molecular weight of the educts. Liquid fuels have a lower enthalpie than gasous fuels, therefor the ISP is lower.

Vaporizing the fuel consumes heat out of the combustion process, that's perhaps the easier understandable formulation.

The ISP is completly independant from the type of engine. It is an upper limit which can only be archieved with an hypothetical ideal engine without heat losses and idefinite expension.
 
Nicknick said:
The ISP is completly independant from the type of engine. It is an upper limit which can only be archieved with an hypothetical ideal engine without heat losses and idefinite expension.
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No, not true. An open cycle gas generator engine has lower ISP than a staged combustion engine.
 
Sferrin said:
Looking at the condensation on the engine it makes me wonder what they're using for propellant. I was hoping air/kerosene but it looks like cryo.
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I was thinking about air-breathers (for instance combustion chambers in turbofan engines) and wondering how much harder it might be to get an RDE to work if the oxidiser is diluted (e.g. all that nitrogen you have in air)?

I'd be interested if anyone could weigh in on this (and also if scaling laws have any effect - certainly a larger chamber could have fewer rotations of the supersonic ignition front per second which might give a bit more time to inject a less dense oxidiser?).
 

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