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If you think of a Carrier-capable US Aircraft from the mid-to-late fifties, planes such as the F-4 Phantom or the A-4 Skyhawk might come to your mind. But among the less known carrier borne jets, there was also the F-8 Crusader II, often considered the last true gunfighter.
While the Crusader did have its time in the spotlight, its proposed successor, the XF8U-3 Crusader III, didn’t quite make the cut and was outperformed by its competition as the true gunfighter era seemed to come to an end. All of the built XF8U-3s were likely scrapped and it has become a footnote in US-Navy history.
History:
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Parallel to the F8U-1 and -2, the Crusader design team of Vought also worked on a larger, more powerful aircraft with better performance. Internally this improved variant was dubbed the V-401.
The project only had superficial resemblance to the Crusader II as the V-401 was larger and equipped with a Pratt & Whitney J75-P-5A engine, the same engine that was used on the F-105, F-107, Lockheed U-2, A-12 etc. The larger engine was able to produce around 131kN of afterburning thrust, giving the Plane better acceleration and quicker response time.
The Crusader III was designed to reach Mach 2.7 for short periods and had two visible features displaying its ability of reaching such speeds, those being the swept-forward “Ferri scoop” inlet, designed by the italian born scientist Antonio Ferri, and two large ventral fins to guarantee safe flight at those excessive speeds.
Those ventral fins were essential for the program to have any hope as stability issues have already made themselves known on the Crusader II as it could not go beyond Mach 1.7 as it simply became unstable. The fins also needed to be able to fold out of the way horizontally to make takeoffs and landings possible as they would extend almost as much as the rudder itself. To ensure that this high performance was reached, Vought made provisions for a XLF-40 Liquid-fueled rocket engine with around 35.6 kN of additional thrust.
Avionics included the AN/AWG-7 fire control, AN/APG-74 radar and a AN/ASQ-19 datalink, giving the possibility to track six and engage two targets at once.
Due to the massive amount of changes that were made from the original F-8U-2, it was dubbed the XF8U-3, the Crusader III.
The XF8U-3 had its first testflight on June 2nd, 1958, and despite claims of the Aircraft reaching speeds around Mach 2.6, it only reached a top speed of Mach 2.39 instead.Its cruising speed was only a bit below its top speed at Mach 2.32.This top and cruising speeds weren’t reached right from the start however. Only on the 14th of August, during its 38th test flight, it achieved Mach 2.0 in level flight for its first time.
Even if some sources claim that Vought projected an even higher top Speed of Mach 2.9 with the tail rockets mounted, the windscreen and aluminum airframe would not have been able to withstand the kinetic forces created at such speeds and melted.
Back in December 1955, the US Navy declared the competition for a Mach 2+ fleet defense interceptor, the competitor to the XF8-U was the first prototype of the F-4 Phantom II, the XF4H-1. Voughts design turned out to be a lot more maneuverable than the XF4H-1. Vought’s chief test pilot, John Konrad, even claimed that the Crusader III could fly circles around the Phantom II.
Another edge Vought had over McDonnell Douglas was their plane’s thrust-to-weight ratio of 0.97, while the early F4H was sitting at a measly 0.87.
Despite all those advantages, there were also downsides. Multiple pilots reported being overwhelmed with the workload required to fly, fire Sparrows and look at the radar illumination from the aircraft, while the Phantom II had a radar intercept officer who shared that workload, leaving the pilot to focus on flying the aircraft.
In addition to that, the “Age of the Gunfighter” was seemingly coming to an end and the Phantom’s ability to carry out air-to-ground and air-to-air missions made it more versatile while the XF8U lacked any multirole capabilities. Just a little while later, the Phantom started replacing the F-8 Crusader II bit by bit and became the daylight air superiority fighter in the Vietnam War.
After the abandonment of the F8U-3 program, all 5 aircraft went to NASA for further atmospheric testing, as the Crusader III was, to the surprise of many, able to fly above 95% of the Earth’s atmosphere.
NASA labeled their newest additions as NASA 255, NASA 226 and NASA 227
If that wasn’t already enough, NASA Pilots at NAS Patuxent River routinely intercepted and defeated U.S Navy Phantoms in mock dogfightings, which eventually made the Navy furious and demanded an end to “the harassment”.
Some sources are unsure whether those planes still exist or if they were scrapped.
Specification:
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Crew: 1
Length: 17.88m
Wingspan: 12.16m
Height: 4.98m
Wing area: 41.8m²
Empty/Loaded mass: 9.915kg/14.660kg
Powerplant: 1 x Pratt & Whitney J75-P-5A afterburning turbojet
Max. Speed: 2.951 km/h
Cruise Speed: 925 km/h
Climbrate: 165 m/s
Ceiling Height: 19.800m
Range: 1.040 km
Offensive Armament: 4 x 20mm Colt Mk12 (planned)
Missiles: 3 x AIM-7 or 4 x AIM-9
Images:
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Videos:
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Vought XF8U-3 Super Crusader III - jaglavaksoldier
Vought XF8U 3 Crusader III American aircraft - MilitArmy
Chance Vought’s F-8 CRUSADER II and III - the Mig Masters - AVhistorybuff
Sources:
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XF8U-3 Crusader III English Wikipedia
XF8U-3 Crusader III German Wikipedia
WebArchive Version of the Article from “Klassiker der Luftfahrt”
Defense Media Network Article
Luftfahrtmuseum Hannover Article (PDF)
Tommy H. Thomason - Vought F8U-3, Crusader III, Super Crusader - ISBN 978-0-9846114-0-9
Barrett Tillman - MiG Master - ISBN 0-87021-585-X
