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

[Humabout]

Originally Posted by thrash

Drag for aerobraking is most efficient from blunt rather than streamlined surfaces. A flat plate perpendicular to the airflow has a Cd ~ 2.0. SMAD III (p. 145) recommends 2.2 for a generic satellite.

What you reference in SMAD III in section 6.2.3 is perterbations due to atmospheric drag that cause orbital decay in satelites. Furthermore, it includes drag from extended solar arrays and does not even address aerobreaking. All of that said, it is pretty obvious that increasing any of Cd, A, or rho (although you can't affect rho with spacecraft design in any meaningful way) will increase the drag force felt by a reentering craft, but intentiinal atmospheric injection with extended solar panels seems like a good way to lose your solar panels. So again, the broad blunt plate for aerobreaking is primarily there to keep shockwaves off the airframe, allowing for lighter construction. The side benefit is slowing down faster, but deceleration will happen no matter what.