Tank mass.

[Der Kosmos]

I apologize if this has already been suggested but.

I noticed that in Career mode that while larger tanks are unlocked latter in the game, there is very little difference between one large tank and several smaller ones. A single larger tank might cause less center of mass issues, but a bunch of smaller tanks will dissipate heat better.

However in real life, a single larger tank will have a better dry mass to total fuel capacity ratio than a cluster of small ones. (The small tanks will also have a higher boil-off rate with cryogenic fuels than a large tank but that isn't modeled in game so it's a non issue.)

Might it be a good idea to make smaller tanks have a higher dry mass in proportion to the larger ones as a balance fix? This would give the player an actual reason to want to unlock bigger tanks instead of just focusing there research on power and experiments.

We already have an example of this sort of thing with the RCS tanks, the inline ones are more efficient than the radial ones.