Republic XF-84H Thunderscreech

The Republic XF-84H, nicknamed the Thunderscreech, was an American experimental turboprop aircraft derived from the F-84F Thunderstreak. A turbine engine was mated to a supersonic propeller, and the aircraft had the potential to set the unofficial air speed record for propeller-driven aircraft, but aerodynamic deficiencies and engine reliability problems led to the cancellation of the program. The name refers to the extremely loud supersonic propeller. After the US Navy canceled its order, the remaining prototypes became pure research aircraft for the Air Force Propeller Laboratory at Wright-Patterson Air Force Base, testing supersonic propellers. Two were built, and the prototypes flew a total of 12 test flights from Edwards, accumulating only 6 hours and 40 minutes of flight time.