[Space, Spaceships] Armor needed for Aerobraking/Re-entry

[RogerBW]

Originally Posted by DaltonS

I searched for the answer to these questions, but the results I got were more confusing than enlightening. How much armor dDR is required for a ship capable of atmospheric re-entry/aerobraking? Can it all be up front, or does there need to be minimum armor on center and rear hull sections? I'm assuming a streamlined hull here; an unstreamlined one would need more. (How much?)

Dalton “is there a Spaceships FAQ?” Spence

My rule of thumb, from back in the 3e days, is DR 100 (i.e. dDR 10) on either the front or the back.

To be fair, the longer you're prepared to take over re-entry or the more dV you're willing to spend, the less heat shielding you need. (An extreme form of this is Vertical Landing, see the box on Spaceships p. 40; that basically brakes to a stop at orbital altitude, then descends slowly.) If you don't mind taking many hours, and you have enough manoeuvre capacity to stay under control, you can decelerate over multiple passes getting a little lower and a little slower each time, and use very little heat shielding.