Comment by hinkley

1 day ago

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.

6 comments

hinkley

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fogh1  1 day ago

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.

  • Gravityloss  9 hours ago

    I wonder if aerospikes were popular as an idea in the J-2 engine ~Apollo era since USA only had gas generator engines (and expander RL-10).

    You can't get to very high chamber pressures with those, and then maybe aerospike was a way to work around the limitations.

    Then XLR-129 and SSME came along with staged combustion cycle and you can just have higher pressure engines. They can both run at sea level and still have a decent efficiency in vacuum.

    The linear aerospike for X-33 was kind of a neat tech demo and fit in with the whole shape of the vehicle and composites, non-tubular tanks and large base area. Maybe too many new things at once in retrospect.

ambicapter  1 day ago

Doesn't seem like a front rotating around the spike would gain that much "spreading out" over a continuous front. At the end of the day, its a spike that narrows to a very small point.

JumpCrisscross  1 day ago

RDEs are far less tested than aerospikes. (In part because you can build a dipshit aerospike in your garage. I don’t know anyone who has made an RDE at home.)