In the early 1950s, the U.S. Navy was seeking a fighter that was capable of launching from an aircraft carrier without the assistance of a catapult. Republic Project 3347 was initiated and the Navy asked for three prototypes but the Navy elected to cancel the contract but not after two prototypes were already nearing completion. Not wanting to waste the effort, the two aircraft, designated XF-84H, were used by the U.S. Air Force’s (USAF) Wright Air Development Center to conduct testing on supersonic propellers. Republic derived the XF-84H from their F-84F Thunderstreak which was already in service with the USAF and fitted a 5,850hp Allison XT40-A-1 turboprop engine into the rear of the fuselage and via an extension shaft, drove a 12ft. diameter Aeroproducts propeller. The engine’s exhaust was shunted out through an afterburner in the tail. A novel feature was an extendable ram air turbine which could power both hydraulic and electrical systems in case of engine failure.
The propeller, at speed, created tremendous torque and the outer portion of the blades spun at supersonic speeds which produced continuous sonic booms even when the engine was idling. So loud was the aircraft that it could be heard some 25 miles away. This made being around the XF-84H hazardous as the concussion from the shock waves from the sonic booms could literally blow unwary ground crew away and the din not only caused nausea and headaches in personnel (even with ear protection), it also disrupted sensitive components due to vibrations in nearby electronics. So loud was the aircraft that radio communication was impossible and signal lights had to be used by ground crew to talk to the pilot. This earned the XF-84H the name “Thunderscreech” (most commonly associated with the plane) but also the “Mighty Ear Banger.” The USAF never put pilots in the seat of the XF-84H and all test flights were carried out by Republic with the first occurring on July 22, 1955. Besides the noise, in the air, the XF-84H suffered from propeller induced vibrations, blade pitch gear failures, hydraulic failures, engine failures, longitudal instability, and that it took nearly a half hour to get the engine warmed up. So bad was the aircraft that after one flight, Republic test pilot Lin Hendrix was quoted as saying to the project’s lead engineer, "You aren't big enough and there aren't enough of you to get me in that thing again".
Ultimately, despite the design’s impressive acceleration, the XF-84H’s numerous problems which could not be easily resolved and the inability for the plane to reach its performance metrics, the USAF canceled the project in September 1956. The second prototype (51-17060 [FS-060]) was scrapped while the first (51-17059 [FS-059]) was mounted on a post at Meadows Field Airport in Bakersfield, California where an electric motor mounted inside the fuselage turned the propeller. In 1992, it became the gate guardian for the Ohio Air National Guard’s 178th. Wing based at Springfield-Beckley Municipal Airport in Springfield, Ohio. Today, it is now housed in the collection at the National Museum of the United States Air Force near Dayton, Ohio on the grounds of Wright-Patterson Air Force Base.
The photograph is of the first prototype and the ram air turbine is not deployed. It is situated just forward of the black marking on the vertical stabilizer. Both prototypes featured the “Stars and Bars” inside the cockpit, behind the pilot’s seat.
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