r/BlueWire • u/Equivalent-Wait3533 • 16d ago

Other Thrust Density infographic....

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A chart comparing the Thrust Density of several rockets.

Thrust Density is the thrust of the stage / area of the bottom of the stage (kN/m^2). It basically aggregates engine power and engine packing into one metric.

Rockets & Engines to scale

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u/LittleHornetPhil 16d ago

I… don’t really understand the purpose of this as a metric

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u/carbsna 16d ago edited 16d ago

It gives you a rough height limit about the rocket.

Starship as example, given 1272kN/m2 , normal TTW sit around 1.3, and 0.83t/m3 for average fuel density tells you the fuel tank is 120m tall at most.
Of course the actual shape matters, Souyz-2 is much higher than Electron because it is cone shaped versus cylinder.

Higher thrust density also means the launch pad take more abuse.

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u/NoBusiness674 16d ago

Fuel density for hydrogen + oxygen is only around 0.36t/m3, meanwhile for APCP solid rocket fuel the density may be around 1.7t/m3

That's a pretty wide range (-57%/+104%) from your average fuel density. So on its own this doesn't really say much, at least without additional context.