What's the best perigee for reentry?

[alex_deltav]

I have conducted~20 tests and figured out that the good perigee for the reentry at the speed 5 km/s is 34 km /-0.5 km. There seems to be a cutoff at 35 km. Did not tested the higher velocity due to the fact that the heating will be introduced.

[Gargamel]

Moved to gameplay questions. 

[schlosrat]

On 4/22/2023 at 2:37 PM, alex_deltav said:

I have conducted~20 tests and figured out that the good perigee for the reentry at the speed 5 km/s is 34 km /-0.5 km. There seems to be a cutoff at 35 km. Did not tested the higher velocity due to the fact that the heating will be introduced.

This will depend on the ballistic coefficient of your recently stage as well as the velocity. If you’re starting from a 100km x 100km circular orbit with a typical small return stage then something around 35 or 40 is good. If you’re coming back from the Mun and you’re too low on fuel to get into some sort of closer orbit before die orbiting you might want to aim for 50 or 55 and aero break your Ap down to where you’re coming back in safely after multiple passes. That’s an extreme example just to set a point on the other side of things, but this also applies for return stages that have a higher ballistic coefficient where you don’t want them to pancake in the denser atmo down low.