Key point: The F-4 was so remarkably adaptable and tough that the last U.S. military Phantom wasn't retired until December 2016.
Had things gone differently, the U.S. Navy's top Cold War fighter jet could have been the F-8 Crusader instead of the F-4 Phantom.
But not the legendary Crusader that bested MiGs over North Vietnam. Instead, it would have been the XF8U-3, dubbed the Crusader III or the “Super Crusader,” a bigger, badder version of the F8U Crusader that the Navy flew in the 1950s and early 1960s.
The Crusader III was developed by manufacturer Chance Vought at the same time as it developed the Crusader I and II models used by the Navy. Despite similar names, the Crusader III was a larger aircraft that actually didn't share many parts with its siblings.
The Super Crusader made its debut flight in June 1958. “The overall performance of the Dash III was outstanding,” says aviation writer Steve Pace in his history of the Crusader. “Officially the Dash III had a recorded top speed of Mach 2.39, unofficially Mach 2.6 was predicted. Some proponents felt Mach 3 was not out of the question. The Super Crusader was capable of continued Mach 2.2 speed at 68,000 feet. It demonstrated 6-G capability and continued 51/2-G turns at Mach 2.2. At the time, the -3 was the only single-engine fighter in the world capable of near Mach 2.4 speed.”
The Super Crusader differed from the Crusader I and II in a variety of areas. It had a more powerful JT-4 turbojet engine instead of a JT-3, which helped give the Crusader III a higher speed, climb rate and maximum ceiling. It also featured all-weather capability, longer range, more advanced flight controls, better maneuverability and two retractable ventral stabilizing fins. Chance Vought even proposed mounting a rocket motor in the Super Crusader’s tail for extra boost.
Ironically, Phantoms were found deficient in Vietnam because they weren’t armed with an internal cannon to supplement the unreliable early-generation air-to-air missiles. The Crusader I and II won plaudits because they did carry cannon—but not the Crusader III. Like the F-4, the Super Crusader was proposed as a cannon-less fighter armed only with seven air-to-air missiles: four Sidewinder heat-seekers and three Sparrow radar-guided weapons. Still, all-missile armament was the fighter fad in the years leading up to the Vietnam War, so the choice was understandable, if mistaken.