How to fly the Apollo Command Module through the Atmosphere
Navigating through the atmosphere can be challenging. First of all, you will need to be on a correct entry trajectory. Coming from the Moon, the Command Module typically hit the upper part of the atmosphere with a velocity of about 36.300 ft/s (or 25.500 ft/s if in Low Earth Orbit). A lunar entry trajectory would have an entry angle of about -6.5 degrees from Local Vertical at the Entry Interface (EI).
The Command Module has been designed to generate lift. Once the spacecraft is in the atmosphere, the lift direction can be controlled to steer the range of the entry (towards a splashdown location) and the G-Load (to a degree).
In this video, I will focus on how to set up the EMS, and how to use it during entry to maneuver through the denser part of the atmosphere. Two things are critical:
Do not dive too steep into the atmosphere for too long (too high G-Forces)
Do not climb out from the atmosphere too Early at too high velocity, as you risk skipping out from the atmosphere
I will manually guide the spacecraft using the onboard instruments down to the safe area when the drogue chutes takes over the velocity reduction before splashdown.
The first milestone of entry is to reduce the velocity down to 25.500 ft/s. At this time, enough energy has been transformed into heat so that you no longer risk the possibility of skipping out of the atmosphere. But this also results in the CM having less energy to alter its trajectory. After this, it's all about controlling the time and range in the atmosphere to reaching the desired splashdown location.