What have you done to advance science lately?

By » Fri, August 10 2012

For any aviation or car nut, the late 1940′s through to the late 1960′s are the heyday of mechanical development. Cars and planes were getting faster, more reliable, and more refined at a blistering pace. But these new developments brought new problems. As is typically the case, the mechanical engineering of faster vehicles massively out paced the development of safety measures meant to address the new dangers brought about when something went wrong.

After WWII the flying branches of the military got together to investigate the number of deaths they were seeing in non-combat aircraft accidents. While the flying service knew that the problem was related to sudden deceleration—it’s not the fall, it’s the sudden stop at the end—they didn’t really have a handle on what was a lethal g-load. They decided to study the problem and enlisted the help of Dr. John Stapp. Dr. Stapp volunteered to lead a group of human subjects in a series of rapid deceleration experiments.

Dr. Stapp and his team would strap themselves onto rocket sleds which rode on a special railbed built by Northrop Aircraft. They would then be shot down the track and decelerated rapidly by either massive mechanical brakes, or pits filled with water. The impacts were recorded on high speed cameras, and their injuries would be logged.

On December 10, 1954 Dr. Stapp was strapped into the Sonic Wind I test sled. For several minutes he sat, atop a sled which mounted nine rocket bottles, each capable of producing 5000 pounds of thrust. Two minutes before ignition two technicians left his side and ran for the safety bunker a few hundred yards away. Stapp had been injured in previous tests; hematomas, broken bones, sand imbedded into his skin. He knew that this test was probably going to hurt. For two agonizing minutes sat there, staring down the track, waiting.

When the countdown reached zero, the nine rocket bottles ignited and Sonic Wind I hurtled down the track. Col. Joe Kittinger, flying a chase plane along the track at 350 miles per, recalls, “he went by me like I was standing still.” Sonic Wind I topped out at 632 miles per hour before hitting the water brake. Stapp’s body was subjected to 46.2 Gs. The stop was so sudden the capilaries in Stapp’s eyes burst, and he was temporarily blinded (his vision would return the next day). He’d broken both of his wrists, several ribs, in addition to the retinal hemorrhages. Stapp was helped to a gurney and taken to the base hospital where he recovered.

Dr. Stapp’s findings not only shattered previously held misconceptions about how many G’s the human body could endure, but also exposed flaws in pilot and passenger restraint. Additionally, with the data collected engineers could develop reasonably realistic crash test dummies, preventing the need for anyone to ever have to endure this sort of testing again. Stapps’ results were also shared with the automobile industry and used to pass the laws making seat belt’s mandatory in all passenger cars. His shoulder restraint system is still used tin every car on the road today.

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