alt Hacker NewsIf the capsule/rocketplane has some lift & preferably steerable aerosurfaces then you can compensate the purely ballistic deceleration somewhat.
But yeah, if it is going down almost vertically then this will not be enough.
If the capsule/rocketplane has some lift & preferably steerable aerosurfaces then you can compensate the purely ballistic deceleration somewhat.
But yeah, if it is going down almost vertically then this will not be enough.
And all but rather short ballistic trajectories (well below orbital speed) will come in at a steep angle.
Unless one has seriously variable aerodynamics, the vehicle will have to swerve to nearly horizontal over a distance of about 1 scale height of the atmosphere, which is about 10 km. The exponentially thinning atmosphere goes from "too thin to matter" to "brick wall" over a short distance.
The acceleration for turning is v^2/r; for v = 5000 m/s and r = 10 km this is 250 g.
Acceleration also limits how rapidly one can reenter from beyond Earth orbit. At > LEO velocity, the vehicle has to use (downward) lift to stay in the atmosphere, and if v is too high the required acceleration is too high.