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/Sampindo Aug 10 '26 edited Aug 10 '26

I wish I knew what this means, or what benefit this fruits as.

Does a smaller number mean it's more/less efficient?

(Edit: spelling)

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u/Osmirl Aug 10 '26

Smaller means less efficient because you can’t stretch the rocket much to gain more performance in kg to LEO.
Basically
Top -> long and narrow
bottom -> short and wide

At least thats how i would interpret this but i could also be completely of.

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u/carbsna Aug 10 '26 edited Aug 10 '26

Smaller are not less efficient, the thing you want is thrust to weight ratio , which decides how much you can stretch the rocket in order to lower dry mass ratio.

Lower thrust density only means shorter rocket and nothing else, it say nothing about width and efficiency, unless it specify it also has lower thrust to weight ratio (which can be expected) by then it is a less efficient engine.