Few aircraft created such an indelible impression on its operators as the XF-84H “Thunderscreech.” Created by Republic Aviation for the U.S. Air Force, this experimental fighter never saw combat, but it left behind plenty of casualties as the loudest aircraft ever built.
The XF-84H was built from a modified F-84F airframe and 5,850 hp (4,360 kW) Allison XT40-A-1 turboprop engine. An added afterburner could have increased its power to 7,230 hp (5,390 kW), but it was never used. Design problems from the very beginning meant this plane was never going to become a staple in the U.S. military’s arsenal.
One of the problems was the noise. Although it was a propellor-driven aircraft, it generated all the problems and virtually none of the benefits associated with jet-powered flight. Unlike standard propellers on other aircraft, the Thunderscreech’s props turned at a speed in excess of the speed of sound. The result was a continuous sonic boom that sent shock waves from the engines for hundreds of yards. The strength of the shock waves was sufficient to knock people over.
Before the plane even took to the air, it made its presence known. The engine could be heard 25 miles (40 km) aways as the pilot prepped the plane for takeoff.
For those unfortunate enough to be on board, the experience was horrifying. The Thunderscreech was notorious for inducing nausea and migraines for crew and ground crew. In one case a Republic engineer was sent into seizures as a result of being too close to the engines’ shock waves.
Since the aircraft was so loud, normal communications became impossible. Edwards Air Force Base air traffic controllers were forced to communicate with the pilots through light signals.
The noise was just one of the aircraft’s problems, however. The first flight of the XF-84F took place on July 22, 1955. The prototype flew a total of 12 test flights and was in the air for a grand total of 6 hours and 40 minutes. The first test pilot refused to fly for a second time because of the plane’s instability in flight. The second test pilot, Hank Beaird, took the XF-84H up 11 times. Ten of those flights ended in forced landings.
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The Air Force cancelled the Thunderscreech program in September 1956.
Presumably, the program would have been cancelled a lot sooner, but those who were working on the project were too deaf by this point to hear the news.
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Categories: Accomplishments and Records, Aviation, Military and Warfare, Transportation
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