Pulling into a loop at 410 knots, “half way up I glanced at the g-meter and saw the maximum-reading needle at 6g with no sign of a blackout,” wrote Royal Air Force test pilot C.M. Lambert in the March 30, 1956 issue of Flight magazine. Lambert had been flying a specially modified Gloster Meteor fighter—while lying on his stomach.
The idea that the body could handle higher G forces lying prone than sitting upright had been around for some time. At the end of World War II, the Luftwaffe had the Henschel Hs 132 bomber/interceptor ready for testing, but it was captured by Soviet forces in May 1945. In September of that year, the United States lost its first prone-piloted jet interceptor, the Northrop XP-79B, on its maiden flight (see “Loser X-Planes,” Aug. 2011). The Soviet Union experimented further in the late 1940s, but it was the RAF’s Institute of Aviation Medicine that researched the only practical prone-flying testbed.
The RAF initially modified an R.S.3 Desford twin-piston-engine trainer for prone flying. Renamed the R.S.4 Bobsleigh, it first flew in June 1951. Because there was no room in the modified cockpit for rudder pedals, all three axes of flight had to be controlled by the stick, which proved much too difficult, leading to development of the Gloster Meteor test machine.
Meteor WK935 was given almost eight feet of stretched nose while keeping the traditional cockpit for a backup pilot. The primary pilot would lie on his stomach on a couch inclined 30 degrees, with his chin on a rest. Legs were bent upward at the knees, and feet were clamped to rudder pedals. Arms rested on padded side rests, where stick and throttle were at hand.
Lambert later recalled being strapped in for the first time: “A few seconds in the trussed chicken state…I could now neither extract my arms from the side channels nor raise my head significantly off the chin rest. Neither could I turn my head sideways,” he wrote in the August 1979 issue of Aeroplane Monthly. He was relieved he never had to bail out. “You can’t eject in any direction lying down,” he wrote. “The only way out of the prone Meteor was to slip feet-first off the rear end of the couch and through the floor.”
The modified Meteor arrived at the Institute of Aviation Medicine in August 1954. Several RAF and industry pilots made test flights, covering all flight phases over 11 months.
Because pilots were unable to see the wingtips, taxiing was a challenge. “One does get a very intimate view of the tarmac,” recalled Lambert in the 1956 issue of Flight. During a loop, “I was able to make use of the floor window for the first and only time,” he wrote. “I could see the horizon and adjust the climb.
“Finally I rolled over and held the aircraft inverted for some seconds. My weight was taken on the straps, at shoulder, waist and thigh and I began to feel a trifle unpleasantly divorced from the machine. It suggested a smoother version of the Cossack trick of riding under the belly of a horse.”
Flying straight and level, “a feeling of complete relaxation could be achieved,” the IAM’s 1955 final report read. High speed in turbulence, however, was unnerving. “There was a tendency to pound up and down on the couch making breathing difficult. It was impossible to keep the head still, and the chin was continually banged on the chin rest, making navigation difficult.”
Overall, prone piloting did improve G tolerance, but the big drawback for fighter jocks was that their ability to look around and back was restricted. By the mid-1950s, anti-G suits had advanced sufficiently that the prone-pilot idea could be scrapped. The homely testbed, with its long snout and twin bubble canopies, is on display at RAF Museum Cosford in England.