In TRO 3057, it says that the Mammoth class are the largest DropShips that can make planetfall, and they have a mass of 52,000 and a Thrust of 3/5. The Behemoth has a mass of 100,000 and a Thrust of just 2/3.
I was wondering which of these (or anything else) is the limiting factor, and therefore would it be possible for a 100,000 ton DropShip to make planetfall if it had a thrust of 3/5 or more? For that matter, would gravity alter the minimum needed to take-off? I assume that provided the Safe Thrust is equal to or greater than the gravity of the planet, it can take off just fine, although the close they are to balanced opposing forces the slower the take-off is going to be and the more fuel is used up due ot gravity drag.
Edit: Having found the rule in TW that says you need a Safe Thrust over 2 to take off, this should probably be in the Developers section.
So now the question is more: Why Safe Thrust 3 to take off from a normal planet? Anything equal to the gravity of the planet would be enough to remain neutral, and anything over neutral means you can get off the planet, with more thrust meaning quicker take-off. So why isn't the minimum SF 2 instead?
Because Safe thrust is not the maximum they can put out, it could even be argued that a safe thrust equal to the gravity means that a take-off is possible, since the gravitational pull gets weaker as it moves away from the planets surface.