How Fast Can You Travel Before It Kills You?
We know that humans have gone 25,000 miles per hour going to the moon—the speed itself is not an issue, it was mainly the acceleration to get out of the Earth’s atmosphere that they had to endure. The two programs I was involved with, the Red Bull Stratus and the space dive—the goal was for a human without a vehicle to break the speed of sound, and that was accomplished because they wore a pressure suit. The reason they didn’t have aerodynamic flail issues was that there’s very little atmosphere above a hundred thousand feet
You can attain very high speeds—at least supersonic ones—as long as you’re protected, or (if you’re free falling from space) you’re at an atmospheric density that’s not going to cause that flail to develop.
Source: gizmodo.com