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A Review of Aerospike Nozzles: Current Trends in Aerospace Applications

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84 points PaulHoule | 1 comments | 26 Jun 25 15:33 UTC | HN request time: 0.223s | source
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hinkley ◴[26 Jun 25 15:57 UTC] No.44388640[source]▶
I have some hope that rotating detonation engines will make aerospikes viable. But I don’t even see them mentioned in this paper.

The idea with the constantly moving flame front is that it spreads the heat out. The limitation with aerospikes is getting enough coolant through the spike. Bells are simpler to cool, which as I understand more than makes up for them needing more cooling.

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fogh1 ◴[26 Jun 25 22:17 UTC] No.44392031[source]▶
I think they were mentioned briefly. Aerospikes can work with rdes potentially if the certain versions catch on, but at the end of the day the heat fluxes are even worse for the detonation based engines. The main reason aerospikes don’t make sense is that you adding more area that gets the highest amount of heat flux and your plumbing and cooling jackets becomes a nightmare.
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1. hinkley ◴[28 Jun 25 17:03 UTC] No.44406265[source]▶
The estimates are that a fully functional RDE will be up to 25% more efficient than a standard bell/deflagration design.

Efficiency means less heat per kg of mass to orbit. And with the rocket equation, that’s a lot less engine per kg of payload.

Efficiency means either less heat, or intensely more incentive to solve the heat problem even with unobtanium. You could make the damned things out of molybdenum, which has 8 times the thermal conductivity of titanium, and a higher melting point.