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In the history of aviation, few aircraft have had as infamous a reputation for noise as the XF-84H Thunderscreech. Built as an experimental jet by Republic Aviation in the 1950s, the XF-84H was an ambitious attempt to push the limits of speed and power. However, this pursuit of performance came with a flaw so significant that it quickly became one of the most notorious aircraft of its time. Its insane noise levels weren’t just a minor inconvenience—they were so loud that they had a profound physical effect on ground crews, causing them to become ill, sometimes even unable to continue their work due to the overwhelming sound.
The story of the XF-84H begins with the growing interest in jet propulsion during the Cold War, as both the United States and the Soviet Union raced to develop faster, more powerful aircraft. The XF-84H was a turbojet-powered aircraft designed to reach high speeds, and it was part of the Air Force’s quest for high-performance experimental aircraft that could potentially be adapted for military use. The design was based on the Republic F-84 Thunderjet, a solid and successful platform, but engineers wanted something faster and more powerful. The result was a new jet with a turbo-prop engine mounted on top of the aircraft, an unconventional setup at the time.
What made the XF-84H different from most jets was its use of a turboprop engine designed to give it more thrust. However, this unique choice of propulsion turned out to be a catastrophic one. The turboprop engine produced a sound so intense that it went well beyond the tolerable levels for human ears. The engine created a high-pitched, shrieking noise that could be heard miles away and was much louder than typical jet engines of the era. The noise was a result of the aircraft’s propeller blades spinning at incredibly high speeds and creating disruptive air pressure waves.
The decibel level produced by the Thunderscreech was off the charts—measuring at over 150 decibels, roughly equivalent to the sound of a rocket launch or a jet engine at takeoff at close range. To put this in perspective, sounds at or above 120 decibels can cause immediate hearing damage, while sounds over 180 decibels can cause severe physical harm. In the case of the XF-84H, the noise was so unbearable that ground crew members working around the aircraft were forced to wear ear protection and often still found it difficult to work near the plane. In fact, the noise was so overpowering that it reportedly made people nauseous, causing headaches and physical discomfort, and on several occasions, workers had to leave the area to recover from the effects of the noise.
Despite the Thunderscreech’s promise of increased speed and advanced technology, the aircraft became a logistical nightmare. It was supposed to be the future of military aviation, but its extreme noise rendered it nearly impossible to operate in real-world conditions. The ground crews working to maintain the aircraft found it physically debilitating to be near it for extended periods. For this reason alone, the plane earned a reputation not just as a technological failure, but as a flying hazard to anyone in its vicinity.
The aircraft’s flight characteristics weren’t much better than its ground performance. Although it had the potential to reach speeds well above Mach 1 (the speed of sound), the handling and maneuverability were poor, and it never lived up to its promise as a high-performance fighter. Its performance was inconsistent, with the noise levels further compounding the problems it faced in terms of stability and pilot comfort.
The Thunderscreech was ultimately deemed a failure by the U.S. Air Force. The aircraft’s aerodynamics didn’t meet the requirements, and its turbo-prop engine proved to be both impractical and unacceptable for operational use. The extreme noise levels made it unsuitable for any military role, and it was eventually retired from service. Only a few prototypes of the XF-84H Thunderscreech were ever built, and none of them went into full production.
While it may not have made a lasting impact on military aviation in terms of technological advancement, the XF-84H Thunderscreech remains a fascinating case study in the pursuit of performance at all costs. Its extreme noise levels are a powerful reminder that, in the world of aviation, speed and power must be balanced with the practicality of maintaining and operating such machines. The Thunderscreech will always be remembered as an aircraft that pushed the boundaries of aviation technology but ultimately served as a cautionary tale of engineering gone wrong. Its loud, shrieking presence may have failed to make a lasting mark on military history, but it certainly left an unforgettable impression on those who heard it in action.