Acceleration and deceleration testing. Series of images of Colonel John Stapp in a rocket sled seat during high G-force acceleration and deceleration testing. These tests revealed the effects of rapid acceleration and deceleration on the human body. On December 10th 1954, Stapp reached 632 miles per hour in five seconds before being brought back to rest in just over a second, with a force of over 40 Gs. Despite initial blindness and collapsed lungs, he quickly recovered, proving that it was possible to survive an ejection from a supersonic aircraft. His participation in these tests led to him being called \The Fastest Man on Earth\.