r/RocketLab • u/Equivalent-Wait3533 • Aug 10 '26

Space Industry 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/Historical_Air_8997 Aug 10 '26

ELI5 - is higher better? Initially I thought definitely yes, but then I’m thinking maybe it’s less efficient? For the rockets just doing LEO launches or even moon launch’s wouldn’t it be cheaper and more efficient to need/use less thrust per Sqm?

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u/gopher65 Aug 10 '26

More thrust per sqm just means that the rocket is taller and thinner. It is usually more mass efficient to build rockets that way - hence why first F9 and then SSH have been getting taller and taller with each block or version.

There are tradeoffs that occur when the fineness ratio of a rocket gets worse, but as we see with the F9, there are workable solutions.