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23-621: F84 or F-84 may refer to; F-84 Thunderjet , an early American straight-wing jet fighter F-84F Thunderstreak , a swept-wing development of the Thunderjet XF-84H Thunderscreech , a turboprop variant of the Thunderstreak HMS Exmouth , a Blackwood class frigate the ICD-11 medical code for Pervasive developmental disorders [REDACTED] Topics referred to by

46-543: A fatal sink rate was induced. Additional instrumentation and an automatic decoupler was added to the second prototype, but by the time it was ready to fly on 3 April 1952, sixteen months had passed, and with all-jet designs being developed, the A2D program was essentially dead. Total flight time on the lost airframe was barely 20 hours. Allison failed to deliver a "production" engine until 1953, and while testing an XA2D with that engine, test pilot C. G. "Doc" Livingston pulled out of

69-657: A turboprop-driven aircraft. Three proposals were put forth in the next year and a half: the D-557A, to use two General Electric TG-100s (T31s) in wing nacelles; the D-557B, the same engine, with contra-rotating propellers ; and the D-557C, to use the Westinghouse 25D. These were canceled due to engine development difficulties, but BuAer continued to seek an answer to the high fuel-consumption of jet aircraft . On 11 June 1947 Douglas received

92-848: Is also inconsistent with data from the National Museum of the United States Air Force, which gives a top speed of 520 mph (840 km/h) (Mach 0.70), nonetheless, making the XF-84H the fastest single-engine propeller-driven aircraft until 1989 when " Rare Bear ", a highly modified Grumman F8F Bearcat , reached 528 mph (850 km/h) (Mach 0.71). Two prototypes were built (51-17059 and 51-17060), with buzz numbers FS-059 and FS-060 . General characteristics Performance Related development Aircraft of comparable role, configuration, and era Related lists Douglas A2D Skyshark The Douglas A2D Skyshark

115-563: Is different from Wikidata All article disambiguation pages All disambiguation pages XF-84H Thunderscreech Although the USAF Wright Air Development Center was the key sponsor of the Republic Project 3347 turboprop fighter, the initial inception came from a U.S. Navy requirement for a carrier fighter not requiring catapult assistance. Originally known as XF-106 (a designation later reused for

138-617: The Convair F-106 ), the project and its resultant prototype aircraft were redesignated XF-84H, closely identifying the program as an F-84 variant, rather than an entirely new type. With a projected contract for three prototypes, when the US Navy canceled its order, ultimately, the remaining XF-84H prototypes became pure research aircraft built for the Air Force's Propeller Laboratory at Wright-Patterson AFB to test supersonic propellers in exploring

161-594: The Navy's letter of intent for a carrier-based turboprop. The need to operate from Casablanca -class escort carriers dictated the use of a turboprop instead of jet power. While it resembled the AD Skyraider , the A2D was different in a number of unseen ways. The 5,100- equivalent shaft horsepower (3,800 kW) Allison XT40-A2 engine had more than double the horsepower of the Skyraider's R-3350 . The XT40 installation on

184-631: The Republic test pilots assigned to the program, flew the aircraft once and refused to ever fly it again, claiming "it never flew over 450 knots (830 km/h) indicated, since at that speed, it developed an unhappy practice of 'snaking', apparently losing longitudinal stability". Hendrix also told the formidable Republic project engineer, "You aren't big enough and there aren't enough of you to get me in that thing again". The other test flights were fraught with engine failures, and persistent hydraulic, nose gear, and vibration problems. Test pilot Hank Beaird took

207-512: The Skyshark used contra-rotating propellers to harness all the available power. Wing root thickness decreased from 17% to 12%, while both the height of the tail and its area grew. Engine development problems delayed the first flight until 26 May 1950, made at Edwards Air Force Base by George Jansen . Navy test pilot Cdr. Hugh Wood was killed attempting to land the first prototype XA2D-1, BuNo 122988 , on 19 December 1950, on its 15th flight. He

230-483: The XF-84H had incredible acceleration but soon its impracticality was discovered. It was unsuited to combat due to the engine's 30-minute warm-up time, but the most serious concerns were vibration generated from the 12-foot diameter propeller and mechanical failures of the prop pitch gearing. The prototypes flew a total of 12 test flights from Edwards, accumulating only 6 hours and 40 minutes of flight time. Lin Hendrix, one of

253-415: The XF-84H up 11 times, with 10 of these flights ending in forced landings . The XF-84H was almost certainly the loudest aircraft ever built, earning the nickname "Thunderscreech" as well as the "Mighty Ear Banger". On the ground "run ups", the prototypes could reportedly be heard 25 miles (40 km) away. Unlike standard propellers that turn at subsonic speeds, the outer 24–30 inches (61–76 cm) of

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276-475: The XF-84H's crew on the flight line by light signals . After numerous complaints, the Air Force Flight Test Center directed Republic to tow the aircraft out on Rogers Dry Lake , far from the flight line, before running up its engine. The test program did not proceed further than the manufacturer's Phase I proving flights; consequently, no USAF test pilots flew the XF-84H. With the likelihood that

299-631: The already considerable noise from the subsonic aspect of the propeller and the T40's dual turbine sections, the aircraft was notorious for inducing severe nausea and headaches among ground crews. In one report, a Republic engineer suffered a seizure after close range exposure to the shock waves emanating from a powered-up XF-84H. The pervasive noise also severely disrupted operations in the Edwards AFB control tower by risking vibration damage to sensitive components and forcing air traffic personnel to communicate with

322-402: The blades on the XF-84H's propeller traveled faster than the speed of sound even at idle thrust, producing a continuous visible sonic boom that radiated laterally from the propellers for hundreds of yards. The shock wave was actually powerful enough to knock a man down; an unfortunate crew chief who was inside a nearby C-47 was severely incapacitated during a 30-minute ground run. Coupled with

345-461: The combination of propeller responsiveness at jet speeds. The XF-84H was created by modifying a F-84F Thunderstreak airframe, installing a 5,850 hp (4,360 kW) XT40-A-1 turboprop engine in a centrally-located housing behind the cockpit with a long extension shaft to the nose-mounted propeller. The turbine engine also provided thrust through its exhaust; an afterburner which could further increase power to 7,230 hp (5,390 kW)

368-580: The design was that the XF-84H was the first aircraft to carry a retractable/extendable ram air turbine . In the event of engine failure, it would automatically swing out into the airstream to provide hydraulic and electrical power. Due to frequent engine problems, as a precaution, the unit was often deployed in flight. After manufacture at Republic's plant in Farmingdale, Long Island, the two XF-84Hs were disassembled and shipped via rail to Edwards Air Force Base for flight testing. First flown on July 22, 1955,

391-625: The engine and equipment failures coupled with the inability to reach design speeds and subsequent instability experienced were insurmountable problems, the USAF canceled the program in September 1956. Although The Guinness Book of World Records recorded the XF-84H as the fastest propeller-driven aircraft ever built, with a design top speed of 670 mph (1,080 km/h) (Mach 0.9) and 623 mph (1,003 km/h) (Mach 0.83) during tests, this claim has been disputed. The unofficial record speed

414-481: The massive torque, including mounting the left leading edge intake 12 in (30 cm) further forward than the right, and providing left and right flaps with differential operation. The two prototypes were equally plagued with engine-related problems affecting other aircraft fitted with T40 engines, such as the Douglas A2D Skyshark and North American XA2J Super Savage attack aircraft. A notable feature of

437-448: The same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=F84&oldid=1258692189 " Category : Letter–number combination disambiguation pages Hidden categories: Short description

460-624: Was an American turboprop -powered attack aircraft built by the Douglas Aircraft Company for the United States Navy . The program was substantially delayed by engine reliability problems, and was canceled because more promising jet attack aircraft had entered development and the smaller escort carriers the A2D was intended to utilize were being phased out. On 25 June 1945, the Bureau of Aeronautics (BuAer) asked Douglas Aircraft for

483-402: Was changed to a T-tail to avoid turbulent airflow over the horizontal stabilizer/elevator surfaces from propeller wash. The XF-84H was destabilized by the powerful torque from the propeller, as well as inherent problems with supersonic propeller blades. A number of exotic blade configurations were tested before settling on a final design. Various design features were intended to counteract

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506-412: Was installed but never used. Thrust was adjusted by changing the blade pitch of the 12 ft (3.7 m) diameter Aeroproducts propeller, consisting of three steel, square-tipped blades turning at a constant speed, with the tips traveling at approximately Mach 1.18 (1,446 km/h). To counter the propeller's torque and " P-factor ", the XF-84H was fitted with a fixed dorsal yaw vane. The tail

529-415: Was unable to check the rate of descent, resulting in a high-impact crash on the runway. The investigation found the starboard power section of the coupled Allison XT40A turboprop engine had failed and did not declutch. This meant the surviving engine was powering the failed engine's compressor, using up much of its available power. Additionally, the propellers failed to feather. As the wings' lift disappeared,

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