So Loud it Made Ground Crews Sick - XF-84H Thunderscreech

[Music] the thunderscreech was an experimental american turboprop plane created as an experimental variant of the f-84 thunderstreak fighter jet [Music] development began after the navy issued a requirement seeking a carrier fighter that could take off without a catapult a problem still facing jet-powered aircraft at the time even though the navy would cancel its order the us air force would absorb the project for testing the air force hoped to create a plane capable of breaking the unofficial record for the fastest propeller driven aircraft [Music] the thunderscreech's turbo engine was ideally suited for a supersonic propeller at first they promised that the aircraft would reach over a thousand miles per hour however this hope was dashed soon after aerodynamic deficiencies and interim reliability issues doomed the program [Music] not to mention that the propeller was so loud it reportedly made crews on the ground physically sick early fighter jets had issues with increased acceleration and struggled to take off on short runways whenever a pilot needed to hit the gas to correct an approach or perform a go-around it resulted in a terrible situation similar to accelerating from five miles per hour in a sports car at top gear republic's xf-84h thunderscreech attempted to solve these issues in 1955 they introduced a stubby high speed on the new jet the thunderscreech named after the terrible noise of the supersonic prop tips when operating resulted in the loudest and most disruptive aircraft ever built by june 1945 the american navy started exploiting turboprops or prop jet concept as a new solution to issues with earlier jets the idea was that a gas turbine engine could drive a propeller at optimum revolutions per minute during flight the power output would in that case be controlled by modifying the pitch or angle of attack of the blades the turboprop engine was considered quicker and more easily manageable than a jet engine it also provided the additional benefit of less fuel the navy preferred an allison gas turbine engine created in 1944 under the label t-38 it produced 2 250 shaft horsepower with a considerable 14 300 revolutions per minute however a reduction gear ratio decreased it down to only around 2100 revolutions per minute nevertheless the navy was interested in the development of allison's two turbine engine the t-40 expected to generate 7 500 shaft horsepower they believe the t-40 added to two t-38s would result in an unbelievable aircraft the idea was that the t-40 engines could counteract the torque by counter-rotating propellers making the plane more manageable while flying at low speeds moreover they believe the cruising range could be extended if one of the turbines remained idle during flight [Music] the navy decided to request a series of aircraft using the t-40 they ordered a twin twin-engine bomber for their carriers a single-engine strike plane a four-engine flying boat and two tail-setting vtol fighters the vtol fighters were assigned to convair and lockheed still both proved to be unfortunate designs that never progressed past the prototype stage the two carrier plane contracts were awarded to north american and douglas aircraft neither proved functional due to the engine's incredible unreliability [Music] due to this string of unsuccessful developments the piston engine skyraiders from douglas aircraft served in vietnam for around 20 years past their successors initial construction [Music] the air force in turn initiated a contest for error products curtis wright and hamilton's standard to create a high performance propeller only error products would design a functioning prop a strange tri-bladed air screw with wide rectangular rip blades at 12 feet in diameter the prop was intended for a constant rotation of 3000 revolutions per minute this left the outer 20 or so inches of the blades at supersonic mach 1.18 speeds republic aviation's xf-84h was superficially similar to the f-84f thunderstreak with most similarities coming from shared parts still the air intakes were placed at the wing source similar to the photo reconnaissance variant of the thunder streak the fuselage of the new aircraft was wider to give room for the t40 twin turbine engine at the back of the cockpit furthermore two lengthy extension shafts were placed through the cockpit to drive the single prop utilizing a reduction gear since the propeller generated such power it also increased turbulence to solve the issue the horizontal tail surfaces were lifted and placed on the top of its tail fin saving it from the prop wash to assist with stability another vertical fin was placed over the cockpit further attempts to manage the torque included moving the port side leading edge air intake closer to the starboard intake and an optional asymmetrical wing flap the aircraft was the first to feature a fully retractable and extendable ram air turbine which was somewhat helpful considering that the plane would struggle with various engine issues the finished xf-84h was notably different from the f-84 and the air force temporarily considered changing its designation to f-106 but ultimately gave that designation to conveyor's delta dart the xf-84h had several revolutionary features including its after-mentioned retractable riamir turbine and its afterburner [Music] the aircraft went down in history as the only turboprop with afterburners which boosted output to 7400 horsepower allowing it to fly at supersonic speed unfortunately these attributes coupled with the afterburner were never tested the program was cancelled before it ever really commenced [Music] the xf-84-h prototypes were plagued by engine driveshaft and gearbox issues the worst and most cumbersome aspect of the experimental aircraft was the screeching howl generated by the supersonic propeller blades [Music] republic manufactured two prototypes at its farmingdale long island plant they were then disassembled and shipped in different containers by rail to edwards air force base to undergo testing the first prototypes made in flight was july 22 1955. while the aircraft yielded fantastic results with acceleration several issues quickly became apparent it turned out that the engines needed 30 minutes to warm up before taking off solely for this reason the air force deemed it unfit for combat but furthermore it generated intense vibration from its 12-foot diameter propeller two it suffered from mechanical failures from the prop pitch gear these two prototypes completed a small number of test flights racking up a mere six hours 40 minutes of flight only two civilians ever partook in the tests one lynne hendricks refused to fly it ever again telling republic engineer quote you aren't big enough and there aren't enough of you to get me in that thing again the other test pilot hank beard conducted the rest of the 12 flights due to engine failures and persistent vibration problems 10 of his 11 trips concluded with emergency landings dearly understated the following about his experience quote it became a handful when you got it out around 400 knots the propeller governor would start surging and the airplane would roll rather violently the resulting vibrations were so bad because ostensibly the entire airframe was trying to torque around its own prop shaft making it rotate left in contrast the prop turned to the right the flight experience was so terrible that neither prototype was ever flown by an air force pilot giving the aircraft a lonely record in aviation history the biggest issue with the aircraft was the noise which gave it the nicknames thunderscreech and the mighty earbanger while taxiing the xf-84h could be heard from up to 35 miles away the outer edges of the propeller blades were traveling faster than the speed of sound even during idle thrust this caused a recurring sonic boom that went for hundreds of yards or so the shockwave from the boom was strong enough to knock down anyone near it to the ground for example a crew chief working on a nearby c47 was incapacitated for 30 minutes when he was knocked over by a ground run this coupled with the engine's considerable noise resulted in the aircraft's ground crews being notably nauseous and reportedly suffering from headaches most troubling of all one of the republic aviation engineers had a seizure after being hit by the shock waves the issues were so disruptive that it even affected operations at the control tower for edwards air force base almost damaging sensitive components through the vibrations as a solution air traffic controllers had to turn off several devices and detect the plane by light signals held by personnel as no one wanted to be an unintentional victim of the shockwaves this direction resulted in multiple complaints as the air force flight test center received more and more complaints they ordered republic aviation to tow the plane out to rogers dry lake before test flights so it didn't disturb anyone the wide array of issues resulted in no further testing beyond phase one the air force canceled the program in september 1956 the guinness book of records reported that the aircraft was the fastest propeller plane ever constructed its design had a top speed of 670 miles per hour its test supposedly yielded a maximum speed of 623 miles per hour the claim has been repeatedly disputed for its inconsistency with the data collected by the national museum of the us air force which marks the top test speed at 520 miles per hour the 1989 rare bear version of the grumman f8f bearcat holds a more established record of 528 miles per hour once it became evident that the aircraft would not work except when attempting to land on deck they decided to back out of the project only two prototypes were ever built although republic aviation had estimated that the xf-84h would be capable of reaching a top speed of 670 miles per hour it never achieved an in-flight speed above 450. had it successfully performed as intended it would have become the fastest propeller airplane ever instead the russian tupolev tu-95 holds that record for its capability to cruise at 545 miles per hour with a top speed of 575 miles per hour due to its four 14 800 horsepower turbo propellers one of the two prototypes went on to serve as a gate guard at the airport in bakersfield california until it was sent to the national museum of the us air force in 1992 it remains there to this day [Music] so you

Channel: Dark Skies

Views: 600,196

Rating: 4.8400259 out of 5

Keywords: thunderscreech, XF-84H Thunderscreech, xf-84h, aviation, airplane, airplanes, aircraft, jet, propeller, air force, us air force, usaf, experimental, footage, flight, history channel, aviation channel, documentary, turboprop, jet engine, united states air force, fighter jet, plane, flying, planes, jets, history, loud, military news, aerospace

Id: bx2F9PZlCqY

Length: 12min 55sec (775 seconds)

Published: Fri Aug 21 2020

Reddit Comments

[u/LambdaMale]

Wild guess, but I assume the pilot put it there. From what I understand, the XF-84 never made it out of testing and was only flown by test pilots.
The company was based in NY, the aviation test range was in Ohio, so either a test pilot or an engineer put it there.

[u/oldenglishhalf40]

The US military recruiting pool is mostly from the south, and mostly due to crushing poverty. Until recently the flag was visibly all over US military bases (and kind of still is, just not as visible). Fun fact - when the USMC overtook Shuri castle on Okinawa, the first flag raised was the only flag the marines had handy - the confederate flag.

It was up for 2 or 3 days before it was ordered to be replaced with the US flag. The commander insisted that the work to take the castle from the Japanese was not just the effort of southerners, but that marines came from across the US.

[u/beachedwhale1945]

Others have noted this was probably a choice of the pilot, and there were only two Republic test pilots to fly the aircraft (no USAF pilots ever did). We have this video showing it in FS-060 and this photo showing it in FS-059, so if it was a pilot decision it was Hank Beaird. According to his obituary he grew up and went to college in Alabama, which further supports the hypothesis, though I cannot quickly find a photo of another aircraft he flew with the battle flag in the canopy (granted the pickings are slim).

[u/Blackhawk2914]

I had come across this video and while watching it I had noticed the Confederate battle flag in the aircraft window. Does anyone know what that's there for?

I was thinking it was the Mississippi State flag but it doesn't look like it.