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Best of 2020: The Republic XF-84H “Thunderscreech” In Action


Best of 2020: The Republic XF-84H “Thunderscreech” In Action

By nature, any aircraft is going to be loud on the outside. I’ve got a decade of experience in that world…APUs, turbines, propellors, rotorcraft, name it, it’s loud. Earplugs were not only second nature, they were pretty much life itself. The loudest thing I’ve ever been subject to was finding myself way too close to the end of a runway in Virginia as a B1-B Lancer was taking off under full afterburner…I’m certain that if I’ve suffered hearing loss, that one instance was half of the loss easily. It wasn’t a scream, it was just a ripping, tearing noise, as if the supersonic bomber was tearing earth and sky a brand new one.

By comparison, the B-one has nothing on this beauty. Meet the Republic XF-84H “Thunderscreech”. Two were built, they didn’t fly seven hours between the two of them, test pilots were scared shitless of them and they might be the most prissy flightline queen ever made. For starters: a Thunderscreech required a 30-minute ground run before the engine was up to temperature. In truth, that’s not too out of the ordinary, but that’s where we have to point out the Thunderscreech’s reason for existing in the first place.

These aircraft are a product of the 1950s. Jets are flying at this point, but they aren’t trusted. They require long runways and aren’t as razor-sharp as propellor planes have been. You know, new technology teething issues. The original request came from a U.S. Navy proposal for a carrier fighter aircraft that didn’t need a catapult to be launched. The design was based on the F-84F Thunderstreak fighter/bomber, but the powertrain was changed up to a Allison XT40-A-1 turboprop engine that used a long shaft to drive an Aeroproducts propellor that was designed to spin at Mach 1.18.

So what was the issue with this thing? For starters, it was loud. Epically loud. Loud with a capital “F”. During that half-hour run-up, the aircraft could be heard from 25 miles away. And if that isn’t enough, the poor bastards on the flightline really got an earful and a half. There are stories of men being knocked to the ground by the constant sonic boom that was plainly visible and radiated for hundreds of yards; a crew chief inside of a C-47 made sick as the Thunderscreech made the Skytrain an echo chamber from hell; and at least one known instance of an engineer who went into seizures as a result. The second part was that this was lesson in fear for pilots. According to Lin Hendrix, a Republic test pilot, the aircraft would start “snaking” (losing stability nose-to-tail) and after his first flight, he not only refused to fly it again, he threatened bodily harm to anybody who would dare try to force him into the cockpit.

Out of the two airframes, one still exists at the National Museum of the United States Air Force at Wright-Patterson AFB near Dayton, Ohio. The other airframe was presumed to be scrapped sometime near or after 1956, shortly after the project was binned. The Thunderscreech never made it past initial tests, and for that, it’s probably for the better. Mainly, because there was an afterburner fitted that never got tried out. Chances are good that nobody had the cojones to flip that switch.


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4 thoughts on “Best of 2020: The Republic XF-84H “Thunderscreech” In Action

  1. Matt Cramer

    A propeller with supersonic tip speeds sounds like a horrible idea – but I guess there are some things you can’t tell just how horrible they are until you try.

    Now…. what would be the best use of that 5000 hp double turbine engine if it had survived? Unlimited hydroplane racing? Tractor pulling?

    1. Loren

      Running propeller tip speeds beyond mach 1 where efficiency surely drops to crap and then using a contra-rotation dual prop scheme to add an extra noise element has had the Russian Tu-95 bomber trailing the jet-powered B-52 by only around 100mph, which is pretty good, for decades. I don’t get it either, I guess it just goes to show that if you beat on something hard enough (incl. air) you -can- always get a little more. Also that in the Soviet air force, if you cared about noise you were a pussy.

  2. Chris Webster

    The surviving airframe spent many years on a pylon at Bakersfield Ca, before going to the USAF museum. I saw it in 1996, and was told that the prop would windmill in a strong wind. Also heard there was an electric motor to turn it.

  3. Chris Webster

    The surviving airframe spent many years on a pylon at Bakersfield, Ca, before going to the USAF museum. I saw it in 1996, and was told that the prop would windmill in a strong wind. I’ve also heard that it was turned by an electric motor.

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