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Fifty-six years ago this month, USAF Lieutenant Colonel John Paul Stapp set a record for human G-tolerance when his Sonic Wind #1 rocket-powered test sled decelerated from 632 mph to a full stop in roughly 1.4 seconds.  In so doing, Stapp endured a deceleration load equal to 46.2 times his weight.

The period immediately following World War II marked the beginning of a steady rise in the speed and altitude capabilities of military aircraft.  These performance increases subjected aircrew to wider ranges of flight loads and physical stresses.  Manifold aeromedical issues and crew safety concerns arose; particularly in the area of emergency escape from a stricken aircraft.  

Abandoning an aircraft in flight under emergency conditions and surviving the experience has always been a sporty proposition.  Ejection forces, wind blast, body limb flailing, parachute opening shock levels, and the like make it so.  Add to this list the effects of atmospheric temperature, pressure and oxygen concentration, and one starts to get an appreciation for the severity of the situation.

John Paul Stapp was a USAF physician who had an abiding interest in the aeromedical aspects of emergency escape.  He knew that too many pilots were dying in situations that could have been survivable if proper equipment and procedures were available.  Stapp dedicated himself to improving the chances of aircrew survival.

Stapp was a pioneer in scientifically investigating the effects of acceleration and deceleration on the human body.  In March of 1947, he began a series of deceleration tests using a 2,000-foot sled track at Edwards Air Force Base.  A rocket-powered test sled named the Gee Whiz carried test subjects down the track and brought them to a sudden halt to produce specific deceleration levels.

Initially, Stapp’s test subjects were anthropomorphic dummies and primates.  However, he had always held to the belief that the best test subject would be a human.  Better yet, a human who possessed extensive medical knowledge.  Stapp selected himself for the assignment.

Stapp took his first ride down the Edwards sled test track on Wednesday, 10 December 1947.  By May of 1948, he had riden the Gee Whiz a total of 16 times.  One run resulted in a deceleration of 35-G’s.  This meant that Stapp briefly experienced a force equal to 35 times his normal body weight during deceleration.  In so doing, he pointedly dispelled the prevailing notion that a human being could not survive a deceleration level beyond 18-G’s.

Riding the sled was a form of physical abuse.  Among numerous injuries, Stapp received several concussions, broke the same wrist twice, cracked ribs, and sustained retinal hemorrhages for his time on the track.  All in an effort to find ways to preserve the lives of aircrew.  Stapp, other human volunteers and chimpanzees continued sled testing on the Edwards track until 1953.

Stapp transferred to the Aeromedical Field Lab at Holloman Air Force Base, New Mexico in early 1953.  He now had a longer track (3,550 feet) and a faster sled (Sonic Wind #1) with which to expand his deceleration research.  The system was checked-out using a new crash test dummy and then a live primate.   Stapp made the first human run on the Holloman track.

John Paul Stapp completed his 29th and final experimental sled test run on Friday, 10 December 1954.  Propelled by a set of 9 rocket motors producing 70,000 pounds of thrust, the Sonic Wind #1 hit a peak velocity of 632 mph (Mach 0.9 at the test site altitude).  Stapp endured a maximum acceleration of 20 G’s and then an incredible peak deceleration of 46.2-G’s during 1.4 seconds of slow-down.  At that moment, he weighed 6,800 pounds.

Stapp took a severe pounding during his record ride.  There were the “usual” body bruises, lacerations and harness burns.  However, the worse effects involved his eyes.  Both hemorrhaged and were completely filled with blood.  Stapp indicated that all he could see was a watery salmon-colored fluid.  Happily, his vision would return to quasi-normal by the next day.  Stapp sported a pair of world-class shiners as peculiar momentos of his extreme deceleration experience.

Characteristically, Stapp had plans to go faster and endure more G’s.  Indeed, the proposed Sonic Wind #2 test sled would be capable of driving him in excess of 1,000 mph and decelerating at more than 80 G’s.  Such was not to occur as USAF would not allow Stapp to risk all again as a sled test subject.

John Paul Stapp’s legendary work produced enormous dividends in helping develop equipment, techniques and procedures that have saved the lives of countless aircrew.  But the benefits of his research have gone well beyond that.  Today, automobile safety standards are based in large measure on Stapp’s pioneering deceleration work.  His legacy continues in other ways as well.  Indeed, the 54th Stapp Car Crash Conference was held in November of this year.

John Paul Stapp, USAF officer, physician, sled test subject, was a man of uncommon valor and a bonifide hero in the truest sense of that over-used word.  He willingly risked his life numerous times so that others might live.  A man can do no more than that for his friends.  On Wednesday, 13 November 1999, this man among men passed away peacefully in his sleep at age 89.

Posted in Aerospace, History

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