The XF8U-3 first flew on 2 June 1958. During testing, the aircraft reached Mach 2.6 at 35,000 ft (10,670 m). Vought projected a top speed of Mach 2.9, though the windscreen and most aluminum airframes were not designed to withstand the heat of such speeds.
In December 1955, the US Navy declared a competition for a Mach 2+ fleet defense interceptor. Fly-offs against the Crusader III's main competitor, the future F-4 Phantom II, demonstrated that the Vought design had a definite advantage in maneuverability. However, the solitary pilot in the XF8U-3 was easily overwhelmed with the workload required to fly the intercept and fire Sparrows which required constant radar illumination from the firing aircraft, while the Phantom II had a dedicated radar intercept officer on-board.
In addition, with the perception that the age of the guns was over, the Phantom's considerably larger payload and the ability to perform air-to-ground as well as air-to-air missions, trumped Vought's fast but single-purposed fighter. For similar reasons, the Phantom would replace the Navy's F-8 Crusader as the primary daylight air superiority fighter in the Vietnam conflict, although it was originally introduced as a missile-armed interceptor to complement day fighters like the Crusader.
The F8U-3 program was canceled with five aircraft built. Three aircraft flew during the test program, and were transferred to NASA for atmospheric testing, as the Crusader III was capable of flying above 95% of the Earth's atmosphere. NASA pilots flying at NAS Patuxent River routinely intercepted and defeated U.S. Navy Phantom IIs in mock dogfights, until complaints from the Navy put an end to the harassment.[1]
All of the Crusader IIIs were later scrapped.
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http://en.wikipedia.org/wiki/XF8U-3_Crusader_III
