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 equipped with a J75-P-5A engine producing 29,500 lbf (131 kN) of thrust with afterburner. It first flew on June 2, 1958, and reached Mach 2.39 during testing. However, only five airframes were built before the Crusader III program was canceled, as the Navy awarded the contract to the Phantom II instead.
All of the Crusader III aircraft were eventually dismantled.
Yet, in the view of U.S. Naval Aviator Steve Bazer, the XF8U-3 is the finest supersonic aircraft ever built. ‘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.
Bazer continues;
‘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 due to 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.’
JoeBaugher.com notes that, during its flight test program, the XF8U-3 achieved speeds of Mach 2.2 and executed zoom climbs to nearly 90,000 feet. It was capable of maintaining level flight at altitudes between 60,000 and 65,000 feet. The Crusader III, however, was never pushed to its full performance envelope because its acrylic windshield could not tolerate the extreme temperatures encountered at very high speeds and altitudes. Engineers believed that, without this windshield constraint, the aircraft might have been able to reach speeds of Mach 2.7 to 2.9 at 35,000 feet.
If it had entered production, the XF8U-3 would have been the fastest operational jet in the world, with a top speed potentially nearing Mach 3. It offered outstanding acceleration, agility, and stability at high speeds. Pilots found it a pleasure to fly, noting its excellent control response and balance. In every respect, the aircraft was a success, making it unfortunate that the Navy ultimately found no role for it.
Bazer explains;
‘It was purportedly a very capable fighter, not only extremely fast but also 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 engines in the late 1950s and early 1960s were not as reliable as the F-35’s single F135 engine. Never mind that the F-4’s GE J-79s smoked like 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 F8U-3 had an internal cannon, as all-missile aircraft were an early 1960s 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, and the F8U-3 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 was 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-4s and embarrassing them in dogfights, so the top brass in the Navy contacted NASA and requested that they cease any further impromptu activities against their front-line fighter.
• The F-4 was considered quite beautiful in its day. The F8U-3 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 by U.S. Navy
