How Fast Can You Travel Before It Kills You?

The human body can withstand a lot before giving up and dying: falls from second-story windows, years of fevered substance abuse, wolf attacks, etc. We have a pretty good idea of what it can’t tolerate, but some ways of dying instantly have received less attention than others, and speed is one of these. We’ve all seen pictures of people moving at top-speed—but is there a velocity beyond which those blown-back cheeks actually fly off your face?

For this week’s sled run, got up to 46, 47 Gs, and he was probably going close to 5 or 966km an hour. If you looked at his face, you would see that it was being blown and heavily distorted, and that his hands were actually restrained on his lap so they wouldn’t flail around. Speed going through an atmosphere causes what’s called aerodynamic flail, and that can kill you. When you’re in outer space you can go as fast as you want—but you need the protection of a vehicle, or a pressure suit, to keep you from the exposure to the vacuum of space.

We know that humans have gone 40,234km 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.

Once they’re on their way and speeding up, there’s no constraints to speed. We’ll eventually send humans to mars and they’ll be going 56,327km per hour.

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.

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