The McDonnell F3H Demon is a subsonic swept-wing carrier-based jet fighter aircraft designed and produced by the American manufacturer McDonnell Aircraft Corporation. It was the first swept wing jet fighter and the only single-engined carrier-based fighter the company produced. The Demon was developed during the late 1940s and early 1950s to fulfill a United States Navy requirement for a high-performance swept wing naval fighter to succeed the F2H Banshee. On 7 August 1951, the XF3H-1 performed its maiden flight, flown by test pilot Robert Edholm. The original design for a short-range interceptor was reworked into a heavier medium-range all-weather fighter to counter the Mikoyan-Gurevich MiG-15 jet fighter being encountered during the Korean War; however, the addition of about 7,000 lb (3,200 kg) of weight hampered the Demon's performance. The Demon was originally to be powered by the Westinghouse J40 turbojet engine, but the J40 proved unreliable and lacking in thrust, and the program was ultimately abandoned after it became politically controversial in 1955. This necessitated another major redesign of the aircraft to accept the alternative Allison J71 powerplant. On 7 March 1956, the Demon was introduced to operational service. Though the aircraft had insufficient power for supersonic performance and insufficient endurance for its intended general-purpose role, it complemented day fighters such as the Vought F8U Crusader and Grumman F11F Tiger as an all-weather, missile-armed interceptor. The Demon was withdrawn in 1964 and thus did not participate in the Vietnam War. Both it and the Crusader were replaced on Forrestal-class and similar supercarriers by the more capable and versatile McDonnell Douglas F-4 Phantom II, which bears a strong family resemblance, as it was conceived as an advanced development of the Demon. The supersonic F-101 Voodoo of the United States Air Force was similar in layout, but was derived from the earlier XF-88 Voodoo, which also influenced the Demon's layout. Although the existence of the Soviet Union's Mikoyan-Gurevich MiG-15 jet fighter program was unknown to U.S. intelligence at the time, the United States Navy anticipated the appearance of high-performance Soviet jet fighters, and issued requirements for a high-performance swept wing naval fighter on 21 May 1948. McDonnell was one of six aircraft companies that opted to produce a response, beginning development work during 1949. The design team chose to develop an all-new aircraft incorporating a swept wing configuration from the onset rather than adapting a straight wing into a swept wing design as had been done with the competing Grumman F9F Cougar. Roll control was achieved via ailerons augmented by a compact spoiler. Furthermore, both the horizontal and vertical tail surfaces were also swept back.[10] It was the company's first swept wing design, and was amongst the first American aircraft to be primarily armed with missiles rather than cannons. The resulting aircraft, which later received the name Demon, emerged as an all-new design. In order to fulfil the U.S. Navy's requirements, McDonnell agreed to power the aircraft with the Westinghouse J40 engine which was then under development. At the time, the J40 was being promoted by Navy officials for its next generation of aircraft, and was to have thrust of over 11,000 lbf (49 kN)—three times that of the engines used on the McDonnell F2H Banshee. Having gained the interest of U.S. Navy officials, McDonnell was issued with a development contract to produce two XF3H-1 prototypes on 30 September 1949, albeit as a fallback measure to the unconventional Douglas F4D Skyray. At this stage of development, it was envisioned as a day fighter. McDonnell named the aircraft Demon shortly thereafter. The unexpected combat debut of the MiG-15 during the Korean War motivated the U.S. Navy to place the Demon as a top priority, having observed the MiG to have considerably outclassed both the Panther and Banshee; the only American fighter then in service that could equal the MiG was the North American F-86 Sabre, which was only operated by the United States Air Force.[6] Seeking to better respond to the MiG, the U.S. Navy pushed for the aircraft to be heavily redesigned, reorienting it from the short-range interceptor mission once envisioned towards a medium-range all-weather fighter; adapting the design necessitated the addition of 7,000 Ibs. of weight to an aircraft that originally weight 22,000 lbs, thus negatively impacting its performance. Number built: 519 Retired: 1964 For more details of the development, and 8 variants,click here.