In 1954, Col. John Stapp survived 46.2 g, the highest known acceleration voluntarily encountered by a human. Strapped to a rocket sled, Stapp reached a speed of 632 mph (1,017 km/h), breaking the land speed record -- to this day, no one has gone faster on

In 1954, Col. John Stapp survived 46.2 g, the highest known acceleration voluntarily encountered by a human. Strapped to a rocket sled, Stapp reached a speed of 632 mph (1,017 km/h), breaking the land speed record -- to this day, no one has gone faster on