The XF8U-3 Crusader III was the wave of the future. Except that it wasn’t.
Developed by Chance Vought as a successor to the successful Vought F-8 Crusader program and as a competitor to the McDonnell Douglas F-4 Phantom II, the XF8U-3 Crusader III (V-401) was externally similar to the Crusader (it shared with it such design elements as the variable incidence wing) but was larger and shared few components.
The XF8U-3 was powered by a J75-P-5A engine with 29,500 lbf (131 kN) of afterburning thrust, it performed its maiden flight: on Jun. 2, 1958 and attained Mach 2.39 in test flights. Nevertheless the Crusader III was canceled after five aircraft were constructed because the Phantom II won the Navy contract.
All of the Crusader IIIs were later scrapped.
However, according to US Naval Aviator Steve Bazer the XF8U-3 is the best supersonic aircraft ever made. ‘Not to ruffle the feathers of a few of the magnificent people who flew the F-14, F-15, F-16, or F-18, which were all fantastic aircraft, but from a historical perspective, I’ll choose the fighter that never was, the Vought XF8U-3 Crusader III,’ he says on Quora.
“The F8U-3 was flying only five days after its archrival, the McDonnell F4H-1, later to be called the Phantom II. Everyone at Vought was convinced that, of the two competitors, the F8U-3 was the “hot” jet – “really hot,” said Vought test pilot Joe Angelone – the stellar performer that had an inevitably bright future. No one was concerned that on the maiden flight Konrad experienced a throttle jam and had to cut short the flight after 38 minutes. The Crusader III was the wave of the future.
Except that it wasn’t,” explains Robert F. Dorr on Defense Media Network.
‘It was a derivative of the F-8 Crusader, and was powered by one modified Pratt and Whitney J75. It was projected to reach speeds of Mach 2.9, but its aluminum airframe was only certified to speeds of Mach 2.35, for heat buildup limitations. Vought was working on a new windscreen design that would be heat-proof (high dynamic pressures cause a significant temperature increase), allowing the Crusader III to achieve much higher speeds than the Mach 2.35 limit.’
According to JoeBaugher.com, during flight testing, the XF8U-3 demonstrated speeds of Mach 2.2 and zoom climb altitude of nearly 90,000 feet. Sustained altitude levels of 60-65,000 feet could be achieved. The Crusader III was never flown to its limits because of the windshield construction, which was made of acrylic and could not take the high temperatures of the aircraft’s upper envelope. It was thought that without the windshield limitations it could have reached speeds as high as Mach 2.7 or 2.9 at 35,000 feet.
Had it been accepted for production, the XF8U-3 aircraft would have been the world’s fastest jet aircraft in service, with a maximum speed perhaps approaching Mach 3. It had excellent acceleration, maneuverability and high-speed stability. It was a delightful airplane to fly, with excellent control harmony. The aircraft was in every way a winner, and it is a pity that no place in the Navy could be found for it.
‘It was purportedly a very capable fighter, not only extremely fast, but very agile. It could purportedly run circles around the F-4 Phantom II during the design competition, but lost the Navy’s bid for several reasons:
• It had a single engine, vs the F-4’s twin-engine design. Jet engine’s in the late 1950’s, early 1960’s were not as reliable as the F-35’s single F135 engine. Never mind that the F-4’s GE J-79’s smoked liked a pair of flying smudge pots, and could be seen at least 50 miles away. The Crusader-III was smokeless.
• The single pilot in the F8U3 had a difficult time flying, while also running a Sparrow missile intercept. The pilot had to keep the target painted with its radar all the way to missile intercept, and could be overwhelmed with task saturation. The F-4 had a designated RIO for the task of operating the AWG-10 radar system, a human microchip, if you will.
• The days of close-in gunfighting were assumed to be ancient history. Missiles were going to replace guns, period. Neither the F-4 nor the F8U3 had an internal cannon, as all-missile aircraft were an early 1960’s Aviation fad. The “Super Crusader” was going to receive 4 Colt Mk 12 20 MM cannons, but the program was canceled before they were installed.
• The F-4 could serve as a bomber, the F8U3 was an air superiority fighter, and supersonic interceptor only. Unfortunately, the only thing the F-4 ever hit with its bombs was the ground. Even then, it often missed.
• It could fly above 95% of the Earth’s atmosphere, and for this reason, NASA used the 5 that were built as research aircraft. They kept intercepting Navy F-4’s and embarrassing them in dogfights, so the top brass in the Navy contacted NASA, and requested that they cease and desist from any further impromptu activities against their front-line fighter.
• The F-4 was considered quite beautiful in its day. The F8U3 looked like an alligator with a harelip. Looks do count in fighter design, and will be the ultimate tie-breaker. The Crusader-III did easily beat the F-4 in every single phase of flight, but it looked hideous while it was winning. Compared to the Phantom II, it was smaller, lighter, faster, had a greater range, was cheaper to purchase and operate, and could outclimb, and out-turn it, but woof woof woof. Beauty versus the Beast.
Photo credit: U.S. Navy