The clip in this post features a recording of the Republic XF-84H Thunderscreech, a turboprop plane with a supersonic propeller.
The clip in this post features a recording of the Republic XF-84H Thunderscreech, a turboprop plane with a supersonic propeller. This sound (when played at its original volume) caused people to faint, vomit, become slightly deaf, and reputedly soil themselves.
The turboprop-driven Republic XF-84H — a joint Air Force/Navy project — was designed to combine the speed of jet aircraft with the long range, low fuel consumption, and low landing speed of propeller-driven aircraft. The XF-84H’s modified F-84F airframe included a T-tail and a triangular fin behind the cockpit to reduce the effect of torque from the propellers.
The XF-84H also had a propeller that spun faster than the speed of sound that made of it the loudest aircraft ever constructed.
The Navy eventually dropped its order (for the time being, anyway), and the Air Force was left with an experimental airplane that caused a continuous stream of sonic booms from its propeller. As mentioned above, the loud noises caused the ground crews that worked on the plane to vomit and have seizures.
According to Military.com, ‘the XF-84H was riddled with problems from the start. For starters, the supersonic propeller created enough torque and propeller wash to destabilize the plane in flight. Even Republic Aviation referred to the engine as “a monstrosity, a mechanical nightmare.”
‘It would have been useless as a fighter aircraft, because despite its powerful acceleration, it took 30 minutes to prepare for flight. In that time, the ground crews servicing the plane would have their work cut out for them.
‘XF-84 ground crews nicknamed the plane “Thunderscreech,” a play on the nickname of the operation F-84 fighter bomber, because it was so loud. The propeller tips of the XF-84 traveled at Mach 1.18, faster than the speed of sound, producing sonic booms that could be heard some 25 miles away.
‘The noise combined with the shock waves of the booms were enough to effectively cripple the area and any crewmen who might be in it. Crews would have to endure while the XF-84 was powering up for 30 minutes before takeoff.
‘One unlucky C-47 Skytrain crew chief who happened to be in the area while a Thunderscreech was powering suffered a seizure in the back of his aircraft due to the intensity coming out of the XF-84.’
Between July 1955 and October 1956, two XF-84Hs made 12 test flights — 11 of these flights ended with emergency landings. Although the XF-84H was one of the fastest single-engine, propeller-driven aircraft ever built, it never approached supersonic speed. Due to poor performance and high maintenance requirements, the XF-84H never became operational.
The XF-84H remains the loudest aircraft ever built.
H/T Earl Belz
Photo credit: U.S. Air Force