Reentry heat and blackout during re entry in real life

[Pawelk198604]

Re-entry heat in KSP is on 30 km, i wonder on which altitude re-entry heat is in real life, i mean Earth.

I knew that space begin on 100 km, but i wonder on which altitude re-entry ionization plasma appear, does is 100 km?

[K^2]

Ionization plasma is going to be most intense when you pass the lower layers of ionosphere, maybe a bit lower. That's about 80-85km. That's not necessarily when you'll have the peak heating, however. Supersonic heating will depend on density, ambient temperature, velocity, and shape of the craft. So with other things being fixed, that's going to depend on re-entry angle and orbit you are returning from. Unfortunately, I don't know what is typical for that, but I imagine it's a bit lower.

[halamka]

Ionization plasma is going to be most intense when you pass the lower layers of ionosphere, maybe a bit lower. That's about 80-85km. That's not necessarily when you'll have the peak heating, however. Supersonic heating will depend on density, ambient temperature, velocity, and shape of the craft. So with other things being fixed, that's going to depend on re-entry angle and orbit you are returning from. Unfortunately, I don't know what is typical for that, but I imagine it's a bit lower.

Power to ionize the air o2 and n2

[khyron42]

Here's some reading material on real-world reentry ionization, from studies during Apollo. It mentions that "conventional re-entry" is considered to start at 400,000 feet, which would be about 121 km; and it goes over the communication blackouts associated with various phases of reentry.

"Plasma Effects on Apollo Re-entry Communication": http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650019316.pdf