<![CDATA[Question for scifi worldbuilding: could Nuclear Thermal Rockets have higher thrust?]]>NERVA has about 250 kN of thrust at 841 seconds of specific impulse.
Merlin 1D has about 1000 kN of thrust at 311 seconds of specific impulse.
That suggests NTRs have around 4x less thrust, but around 2.7z more efficiency than chemical rockets. At a large enough scale craft, the weight of the engine could be considered irrelevant. But for smaller crafts, the Merlin has a thrust to weight ratio of 184:1, whereas NTRs only ever achieved 7:1 (they hoped to get up to around 35:1 eventually).

I imagine the thrust to weight could be substantially improved by making lightweight reactors, but I'm wondering if anybody knows anything about concepts for higher thrust NTRs?

https://en.wikipedia.org/wiki/NERVA
https://en.wikipedia.org/wiki/SpaceX_Merlin

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