Seat belts, air bags even ejector seats in planes, we take these type of safety devices for granted and they have saved thousands of lives. Virtually anything that carries people these days from cars to planes to spacecraft have been tested using sophisticated test dummies but it hasn’t always the case, in the early days of jet aircraft and at the beginning on the space race some truly brave people risked life and limb in some amazing experiments.
In the 1950’s with the new generation of high-speed jets taking to the skies, escaping from a damaged plane, high-speed banking and acceleration, the risk of high altitude flying and even crash landing all became great unknowns.
In the past animals or even deceased human bodies, cadavers had been used in tests. The problem is that this kind of test subject couldn’t operate equipment during test or report back as to what happened to them and what the effects were on not only their physical condition but just as importantly how it affected their mental capabilities.
However, one man, Capt. John Stapp, a Medical doctor and qualified flight surgeon for the USAF was willing to push the boundaries of what was thought possible, not by performing tests on dummies but on himself.
His first assignment was with the aeromedical lab and was into the effects of high altitude flight.
In 1946 Stapp was flown in the rear a heavily modified B-17 bomber into the stratosphere to a height of around 45,000 ft to see how it would be possible for the crew to survive the cold and lack of oxygen. These tests would be crucial to the future of aviation.
One of the mysteries of high-altitude flying was how could they stop the bends or altitude sickness from occurring, this is the same condition that affected deep-sea divers when they ascended back to the surface too quickly. This happened in the very low-pressure atmosphere at high altitudes or in a sudden decompression event. Nitrogen which is normally dissolved in the blood comes out of solution and forms gas bubbles causing anything from pain and rashes to confusion, unconsciousness or even death in a very short space of time.
Stapp spent 65 hours in the back of the B-17 performing different tests on himself. In the end, he discovered that if you breathed pure oxygen for 30 mins prior to the flight, the condition could be eradicated. This is because he was effectively flushing nitrogen out of his body with the pure oxygen.
This was a major breakthrough and his next task was to lead the aeromedical labs most important research project into the effect of deceleration on the human body and would lead him and his crew to performing some truly eye-watering experiments.
One of the reasons why the USAF wanted to explore the effects of deceleration was that at the time it was thought that 18g was limit that any human could survive. Because 18g was thought to the upper limit, things like harnesses and seats were only rated for up that amount.
However, in numerous occasions on aircraft carriers pilots had survived high-speed crashes and higher forces that should have killed them, yet they walked away and others had proved fatal at very low speed because their harness or the plane’s structure failed.
There was also the upcoming problem of supersonic jet flight and the need to eject at supersonic speeds, no one knew if the crew could survive such an ejection.
The experiments would take place on a 609-meter long track at the Muroc base later renamed as Edwards air force base. This had been previously been used to test captured German V1 flying bombs.
A rocket-powered sled nicknamed the “Gee Whizz” with a wooden windshield to protect the occupant would be propelled down the track and at the other end a set of hydraulic brakes in the track would slow it from 240 km per hour to half that in 1/5th of a second, this would simulate the G-forces in a plane crash.
The sled was meant to use an 84kg dummy named Oscar Eightball but Stapp had other ideas and told Northop manager that he would be the test subject.
Before Stapp did any tests on himself the system had to be tested thoroughly as any mistake could prove fatal.
During one of the setup tests they sent Oscar Eightball down the track with just a lap belt, when the sled hit the brakes they locked up instantly producing 30g. The belt broke and Oscar went through a 2.5cm thick wooden windshield as if it was paper and ended up some 216 meters past the end of the track, clearly, better harnesses where going to be required.
After 35 test runs and 8 months, Stapp thought he and his team had enough experience to start manned tests. The first one was with Stapp on the Gee Whizz facing backwards using just one rocket, this reached 145 km/h and 10g. The next day he added 2 more rockets and reached 320km/h with no ill effects.
Further tests with increasing speeds and differing deceleration rates followed and by August 1948 Stapp had done 16 tests and survived up to 35g. Although Stapp found the earlier tests easy the later ones where much more stressful with him suffering concussions, a broken wrist and cracked ribs.
The most disturbing effect Stapp noted was the whiteouts when facing backwards in the sled, this was because the blood was leaving his eyes and pooling at the back of his head under the high G-force. When he changed to facing forward he experienced red outs, this time the pressure of the blood being forced forwards was bursting the capillaries in his eyes.
This remained a constant issue thru the later tests proving that the eyes were the most venerable parts, though to be accurate it the blood or lack of it which caused the problem.
Although Stapp was reprimanded for exceeding the 18g limit, the data he collected was so useful he was just told to use chimpanzees instead. He had already proved the inefficiency of many harnesses fitted to aircraft and that rear-facing passengers in planes are much more likely to survive a crash than forward facing ones. The air force immediately changed the harnesses in its planes and reconfigured it troop transport planes for rear-facing passengers.
There was still the issue of supersonic ejection but that was beyond the limits of the Gee whizz and although Stapp did some tests a special open cockpit F-89, what became clear was that a new test vehicle was required.
In 1953 a new track was built with a new rocket powered sled called the “Sonic wind No.1 ”. This was capable of reaching 1200km/h and withstand 150g. Instead of using brakes the sled would run thru a water trough using scoops to catch a redirect the water to create the braking.
In November 1953 Stapp was fired down the track at 677km/h, when the sled hit the water it generated 22g, dropping to 15g for 0.6 seconds, twice as long as on the Gee Whizz. Stapp said after wards he felt fine and that hoped to do it again later that day.
It actually took 5 months to do the next test but this time it would be forward facing with no windshield, just a helmet and visor like a pilot would be wearing and the sleds speed would be wound up to the max.
This run would be Stapps 29th and final test. The sled would also be followed by a T-33 jet fighter to observe and takes photos of the test from above.
As the run started the sled accelerated to 1017km/h by its six rockets making Stapp the fastest man on earth, faster than a bullet and exposing him to a wind pressure of nearly two tons and an acceleration force of 20g. Joe Kittinger who was piloting the chase plane said the sled went past him as if he was standing still and he had the throttle wide open doing 560km/h.
Kittinger said when the sled hit the water brake it looked like it had hit a concrete wall, so quick was the deceleration he couldn’t believe anyone would survive it.
But survive it Stapp did, he endured 46.2g for 1.1 seconds, equivalent to a pilot ejecting at Mach 1.6 at 40,000 ft. The jolt he received was greater than that of a driver of a car hitting a brick wall at 195km/h.
When the medics got to the sled, Stapp was conscious but when they saw his eyes they were completely filled with blood. He was taken to hospital and feared that he might have gone too far this time and blinded himself but within 24 hours his sight had returned almost to normal.
Stapp was preparing for an even faster test of 1600km/h, 1000 mph but the top brass thought he was pushing his luck too far and didn’t allow him to continue which was just as well because during an unmanned 80g test the sled came off the rails and was severely damaged, if he had been on board he would have been killed.
Stapp became a great advocate for better safety in cars. In 1966 and because of his work it became law to have seat belts fitted in cars in the US. Although others had done tests, Stapp had taken it to the limit and then some.
Soon dummies would take over but Stapp would continue his work with the aviation and automobile industry up until his death in 1999 at the age of 89.