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The XR-8 was an experimental American helicopter built by the Kellet Autogiro Corporation. It first took flight in 1944. Despite the fact that it was built by an autogiro company, it is in fact a helicopter and is a result of Kellet realizing that the future of rotary aircraft would be in the form of helicopters. The XR-8 (which was later renamed the XH-8) was built during World War II. The point of this experimental aircraft was to demonstrate that twin-rotor helicopters could work. While it did indeed fly and therefore prove its point, the XR-8 also highlighted many new issues that needed to be solved before twin-rotor designs would be practical. The helicopter itself was an egg-shaped aircraft with stubby features. It was equipped with a simple tricycle carriage, just one tail fin and two seats. The two rotors were meshed and offset at an angle of 12.5 degrees. The materials were typical of the time and included a steel tube airframe. The outer skin was a mixture of steel and fabric. The rotors themselves were wooden, which was not atypical for the era. Those meshed rotors were the inspiration behind the nickname for the XR-8: the eggbeater. Initial test flights of the XR-8 revealed directional stability problems and at least one flight there was a potentially dangerous blade collision between rotor blades, something only discovered after concluding the flight. Because of this, Kellet developed a new rigid blade system to replace the first one. Three XR-8s were planned for construction, but only two were ever produced. In 1946 the project was cancelled and the XR-8 prototype was handed to NASA, where it remains today.
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