F8U-3 Crusader III
In 1955 Vought started design of the XF8U-3 Crusader III, a very high performance all-weather interceptor/fighter. Although it carried an F8 designation, it was an entirely new aircraft that was larger and had a more powerful engine than the previous F8s. Vought decided not to call their entry the XF9U-1, which would have been a logical choice. Instead, the the aircraft was designated XF8U-3 Crusader III. The F8U-2 (F-8C) had been considered such a major upgrade that it was initially called Crusader II, so it was logical to call the XF8U-3 Crusader III.
The fuselage was enlarged to accomodate a Pratt & Whitney J75 turbojet, with a thrust almost 60 percent greater than the J57 of the F8U-1 and -2. The lower lip of the chin-mounted intake was raked forward in order to achieve Mach 2+ performance. The intake was of fixed geometry, with no mechanically-complex moving parts. Perhaps the most distinctive feature was the use of a pair of large ventral fins which were extended vertically downward when the aircraft was in flight. These fins were retracted to a horizontal position for landings and takeoffs.
The F8U-3, powered by the Pratt & Whitney J75-P-6 afterburning engine was the fastest accelerating fighter in the world in acceleration from subsonic to supersonic speeds. From a speed of Mach .98 at 35,000 feet to Mach 2.2, it would take only 3 minutes and 54 seconds compared to a time of 9 minutes for a more conventional fighter of that era. The maximum altitude capability for this aircraft, was also impressive. From a sustained flight altitude of 65,000 feet the aircraft could zoom to an altitude approaching 90,000 feet.
First flight of the XF8U-3 was June 2, 1958. During subsequent flights, the XF8U-3 achieved a speed of Mach 2.39 (approximately 1,601 mph) and was still accelerating at 0.1 Mach every 17 seconds. This was extraordinary even when compared to the performance of today's aircraft. The reason for not flying faster was the heat limitations on the plexiglas windshield, which was approaching an external temperature of 325 degrees F.
A design for a laminated glass windshield was under way during the flight test program. This would have allowed the aircraft to achieve its maximum speed potential. It was the opinion of all the test pilots, from the technical data available, that the aircraft could attain a speed close to Mach 2.9 at 35,000 feet (1,950 mph)and there is little doubt that this speed could have been attained. This would have easily made the F8U-3 the fastest jet-propelled fighter- interceptor in the world.
In 1958 there was a congressionally directed competition between the McDonnell F4H (F-4) Phantom II and Vought F8U-3. On December 17, 1958 the Navy announced its decision to proceed with the two-engine, two-place McDonnell Phantom and cancelled the better-performing one-engine, single-place F8U-3. On December 18, 1958 the Navy announced its decision to devote its missile development funds to the submarine-launched Polaris ballistic missile and cancelled the Regulus II program. The loss of two major contracts was a very traumatic experience for the company and especially for the nearly four thousand people who lost their jobs. Many lamented the F8U-3 as the "best airplane we never did buy."
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