page_title: McDonnell F3H Demon
section_title: Development
hierarchical_section_title: McDonnell F3H Demon / Development
caption_attribution_description: The first production U.S. Navy McDonnell F3H-1N Demon (BuNo 133489), in 1955. The F3H-1 was ordered before it s first flight to counter the Soviet MiG-15. However, only 58 aircraft were built and most never flew, because the Westinghouse J40 engine. The aircraft was seriously underpowered and the J40 was prone to inflight explosions and sudden failures. All F3H-1Ns were permanently grounded in July 1955 and the surviving airframes were either used as ground trainers or scrapped. 133489 first flew on 24 December 1953 and was used for service evaluation at the Naval Air Test Center, Patuxent River, Maryland (USA), in 1954.
context_page_description: The McDonnell F3H Demon is a subsonic swept-wing United States Navy carrier-based jet fighter aircraft. The successor to the F2H Banshee, the Demon was originally designed to use the Westinghouse J40 engine, but had to be redesigned to accept the Allison J71 after the J40 suffered severe problems and was ultimately abandoned. Though it lacked sufficient power for supersonic performance, it complemented daylight dogfighters such as the Vought F8U Crusader and Grumman F11F Tiger as an all-weather, missile-armed interceptor until 1964.
  It was withdrawn before it could serve in Vietnam when both it and the Crusader were replaced on Forrestal-class and similar supercarriers by the McDonnell Douglas F-4 Phantom II. McDonnell's Phantom, which was equally capable against ground, fighter, and bomber targets, bears a strong family resemblance, as it was conceived as an advanced development of the Demon. The supersonic United States Air Force F-101 Voodoo was similar in layout, but was derived from the earlier XF-88 Voodoo, which also influenced the Demon's layout.
context_section_description: Development work began in 1949, using a swept wing from the start rather than adapting a straight-winged design as was done with the Grumman F9F Panther. A competing contract was also awarded for the delta wing Douglas F4D Skyray. The Skyray, with a top speed of 722 mph (1,162 km/h), would become the Navy's first fighter to fly supersonic in level flight, while the Demon would never reach that level of performance. The original design work was based at its predecessor, the F2H Banshee. However, departing from its tradition of using two engines, the Demon would result in McDonnell's only single-engined carrier-based fighter, adopting under some Navy pressure, the Westinghouse J40 engine. That engine was being promoted by the Navy for its next generation of aircraft, and was to have thrust of over 11,000 lbf (49 kN)—three times that of the engines in the F2H Banshee. It was the first swept-wing design produced by McDonnell and among the first U.S. aircraft to have missile armament.
  The Navy desperately needed a high performance fighter to meet the challenge of the swept-wing MiG-15 encountered over Korea. Production of the F3H-1N was hastily ordered even before the first flight of the XF3H-1 prototype on 7 August 1951 by test pilot Robert Edholm. The first test flights of the operational design did not occur until January 1953, by which time the Korean War was winding down.
  The F3H Demon was originally designed around Navy's ambitious new Westinghouse J40 which was to offer enough power to use just one engine in a number of new aircraft designs. But the engine would ultimately fail to produce the promised thrust or run reliably. The engine was a major disappointment, producing only half of the expected power. Worse, it was temperamental and unreliable. Of 35 F3H-1N aircraft flown with the J40 engine, eight were involved in major accidents. The first production Demons were grounded after the loss of six aircraft and four pilots. Time magazine called the Navy's grounding of all Westinghouse-powered F3H-1 Demons a "fiasco", with 21 unflyable planes that could be used only for Navy ground training at a loss of $200 million. One high point of the J40 was the 1955 setting of an unofficial time-to-climb record, in a Demon, of 10,000 feet (3,000 m) in 71 seconds. The proposed F3H-1P reconnaissance version was never built. The J40 program was terminated sometime in 1955.
  All the aircraft it was to power were either canceled or redesigned to use other engines, notably the J57 and the J71. The F4D Skyray had been designed to accept larger engines in case the J40 did not work out, and was eventually powered by the Pratt & Whitney J57. But no other engine could simply be fitted into the old Demons, as both the wings and fuselage would have to be redesigned and enlarged. The best alternative turned out to be the Allison J71 engine which was also used in the Douglas B-66 Destroyer. Subsequent F3Hs with this powerplant were designated the F3H-2N. In service, the J71 proved problematic, providing insufficient power for an aircraft of the Demon's size. The engine also suffered from frequent flameouts and compressor stalls. The first Demon with a J71 flew in October 1954. Another significant problem was the reliability of the ejection seats: initial versions were found to be unreliable and were eventually replaced with Martin-Baker ejection seats that were becoming the standard Navy seat of choice due to their higher performance at low altitude and better reliability.
  Despite the problems, the Navy ordered 239 F3H-2s, and the first were deployed in March 1956. 519 Demons were built up to the end of production in November 1959. It was not the Navy's first all-weather interceptor with radar (the AN/APG-51 air interception set was used first on the F2H-4 Banshee). The F3H-2 Demon had the AN/APG-51A, later upgraded to the 51-B version with a tunable magnetron then on to 51-C with better counter-measures in the receiver.
  The F3H-2N's standard armament was four 20 mm (.79 in) Colt Mk 12 cannons. In later years, the upper two cannons were often omi
caption: The first F3H-1N in 1954
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