XF-84H Thunderscreech

The Republic XF‑84H Thunderscreech was an experimental turboprop fighter‑prop prototype developed in the late 1940s as a radical attempt to combine jet speed with propeller thrust. Originating from a 1946 U.S. Air Force requirement for a high‑performance interceptor, Republic Aviation adapted its P‑47 airframe, installing a Wright R‑3350 turbo‑compound engine that drove a 13‑foot diameter, eight‑blade contra‑rotating propeller through a reduction gearbox. First flown on 19 February 1953, the aircraft achieved a top speed of 670 mph (1,080 km/h), rivaling early jets, while generating unprecedented acoustic levels—up to 140 decibels—earning the nickname “Thunderscreech.” The XF‑84H’s innovative features included a full‑metal, low‑drag fuselage, tricycle landing gear, and a hydraulic pitch‑control system for the massive propeller. Despite its impressive performance, the program suffered from severe vibration, propeller blade failures, and pilot fatigue caused by the extreme noise, leading to its cancellation after only 22 flight hours. Nevertheless, the Thunderscreech remains a landmark in aviation history, illustrating the limits of propeller‑driven speed, influencing later turboprop designs, and providing valuable data on contra‑rotating propeller dynamics and high‑power engine integration. Its legacy continues to inspire engineers seeking unconventional propulsion concepts.

Republic Aviation Corporation

XF-84H Thunderscreech

Classification

Production & History

Design & Classification