LF72100 KELLETT XR-10

The XR-10 kellet is a prototype American helicopter with main rotors in a counter-rotating twin-rotor system from the Cold War period. The machine made its first flight in 1947, but never entered mass production. The hull of the helicopter was 8.74 meters long, with a height of 4.19 meters. The main rotors had a diameter of 19.81 meters. The drive was provided by two Continental R-975 engines with 525 HP each. The maximum speed was 190 km / h. The XR-10 helicopter was developed by the US Kellet Autogiro Corporation for the US Air Force. It was a significantly changed development of the XR-8 model. Compared to its predecessor, it had an elongated and raised fuselage, main rotors with a larger diameter, it also received two engines, instead of one, placed in the side nacelles. Efforts were also made to improve flight stability and eliminate vibrations, which are the Achilles' heel of the XR-8 model. However, in the course of testing, the XR-10 turned out to be a rotorcraft difficult to pilot, having problems with the rotor control system, and 1 (out of 2 built) crashed during the crash. Ultimately, the project was abandoned.