A factor I forgot to mention - heavier than air craft, because of their better surface area to weight ratio (ability to be more dense) can pack in more engines for a given amount of surface area - and go faster, and produce more lift per unit of surface area, due to the reduced drag.

So heavier than air craft do NOT have a fixed surface area to weight ratio, they have a surface area/airfoil to power ratio, which can vary widely depending on the effectiveness of the engine.