Rocket Sled

Did you know that one of the world's most famous sayings, Murphy's Law, came out of the American military's experiments with rocket sleds?

Rocket Sled
Lt. Col. John P. Stapp rides the rocket sled at Edwards Air Force Base

It's true. Back in 1948, military personnel were working on a rocket sled experiment at the Muroc Army Air Field (now Edwards Air Force Base) in California. They strapped a chimpanzee into the sled and sent the vehicle down a railroad track at an extremely high speed to measure the g-forces and deceleration effects that occurred during the trip.

After the test, researchers were dismayed to find that the sensors used in the harness's restraining clamps had returned no measurements. Edward Murphy discovered that his assistant had installed the sensors incorrectly, with each one wired backwards.

"If that guy has any way of making a mistake, he will," Murphy complained. His colleagues quickly dubbed the saying "Murphy's Law."  The complaint soon morphed into the law we know today: "If anything can go wrong, it will."

Murphy's Law was popularized during a press conference by John Paul Stapp, the U.S. Army colonel and flight surgeon who headed up the program on which Murphy worked. Responding to a question about why no one had been seriously injured in rocket sled testing, he said engineers always took Murphy's Law into consideration when evaluating what could go wrong.

Rocket Sled John StrappThat was a very smart decision because Stapp's life depended upon it. He rode the rocket sled many times as part of the test program, which was designed to measure the effects of deceleration on the human body. The purpose was to improve the design of aircraft to better protect pilots and passengers.

The rocket sled he used, which was alternately known as the "human decelerator" and "Gee Whiz," weighed 1,500 pounds (680 kilograms) and included 1,000 lbfg (4-kN) rockets that propelled it down the 2,000-foot (610-meter) track at Muroc. There was a 45-foot (14-meter) braking system that slowed the rocket sled down.

Prior to beginning the research, many experts believed that humans could not survive forces above 17 g's. However, Stapp proved them wrong, gradually exceeding this level. Near the end of the program, he was subjected to 46.2 g's and lived to tell about it. For his exploits, he became known as the "fastest man on Earth."

Stapp suffered many injuries during his rocket sled runs, including broken ribs and limbs and a detached retina that caused vision problems for the rest of his life. His sacrifices and courage resulted in many significant changes in aircraft design that greatly improved safety.

Photo: Time-sequence photos of Stapp on the rocket sled "Sonic Wind I" during a 421 mph-run in March 1954

John P Stapp

Murphy's Law

 

 

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