An example of what I mean: Suppose you had a blueprint for a chemical rocket. You build one, and it has mass m and provides thrust x. Suppose you scale the whole blueprint up by 1% and build another. The volume (and therefore the mass) of each part in the rocket has increased by a factor of 1.01*1.01*1.01 = 1.030301, so the new rocket masses 1.030301m. In theory, should it provide 1.030301x thrust? General idea: provided the materials stay within the range of temperatures/pressures/etc in which they function properly--basically, ignoring the engineering problems that would no doubt arise--does doubling the mass of a rocket double its thrust?