North American F-107A: Meet The Ultra Saber
The F-107 was conceived as a nuclear-capable, fighter-bomber version of the F-100 Super Sabre, with a recessed ωɛλρσɳs bay under the fuselage
In the 1950s, the United States Air Force held a competition to design tactical fighter-bombers. North American Aviation entered the competition with the F-107, a design based on the F-100 Super Saber, but with many improvements and radical design features, notably the over-fuselage air intakes. The competition was eventually won by the Republic F-105 Thunderchief, and most of the F-107 prototypes ended their lives as test aircraft. One is on display at the National Museum of the United States Air Force and a second at Pima Air and Space Museum.
The F-107 was conceived as a nuclear-capable, fighter-bomber version of the F-100 Super Sabre, with a recessed ωɛλρσɳs bay under the fuselage. One requirement was to carry the 1,680-pound Mark 7 tactical nuclear gravity bomb as well as smaller nuclear bombs that were expected in the near future. When the centerline recess was not used for ordnance, an additional fuel tank could be carried.
The aircraft was originally referred to as the F-100B, then changed to the F-107A on 8 July 1954, mainly to reflect changes from the Super Saber design. several upgrades including a longer fuselage, an all-moving vertical fin, an automated flight control system, and a system that automatically controlled the amount of air fed to its turbojet engine.
The defining feature of the F-107 is its dorsal-mounted variable-area inlet duct. Although the preliminary design of the air intake was originally located in a chin position under the fuselage like the Vought F-8 Crusader, the air intake was eventually mounted in an unconventional position directly above and just behind the cockpit. The intake also severely limited rear visibility. Nonetheless this was not considered very important for a tactical fighter-bomber aircraft at that time, and furthermore it was assumed that air combat would be via guided missile exchanges outside visual range.
In August 1954, a contract was signed for three prototypes along with a pre-production order for six additional airframes. The F-107 was powered by a Pratt & Whitney YJ75-P-9 turbojet engine, with 109 kN of thrust. The aircraft had a top speed of Mach 2, a range of 2,428 mi, a service ceiling of 53,200 ft, and a rate of climb of 39,900 ft/min.
In flight trials, the F-107 performed well. It achieved Mach 2.0 on Nov. 3, 1956. Pilots praised the aircraft and, contrary to its appearance, were not worried about being swallowed up by its engine: Because of the unusual location of the air intake, it was necessary for the canopy to open straight up rather than in clamshell fashion.
The Air Force order for 33 planes was reduced to three. Despite the failure, the bold ideas of this design were used on North American’s A-5 Vigilante, XB-70 Valkyrie and XF-108 Rapier designs.