F-107 ULTRA SABRE
The F-107A was originally designed as a tactical fighter-bomber version of the F-100, with a recessed weapon bay under the fuselage. However, extensive design changes resulted in its redesignation from F-100B to F-107A before the first prototype flew. Special features included an all-moving vertical fin; a control system which permitted the plane to roll at supersonic speeds; and a system (Variable Area Inlet Duct) which automatically controlled the amount of air fed to the jet engine.
As the North American Aviation YF-107 came into being, the U.S. Department of Defense decided to pit it against the Republic F-105B as a nuclear-capable Mach 2 fighter/bomber for the U.S. Air Force. In August 1954, NAA was awarded a contract for nine YF-107 flight-test vehicles and one static test airframe. However, this number was reduced to three in January 1957.
The YF-107 achieved Mach 1.03 on its first flight in September 1956 and hit Mach 2 in November of that year. To accommodate the XMA-12 integrated fire control system (eventually used on the F-105) the 107's unique intake was located above and behind the flight deck.
In early 1957, zoom climb tests reached an altitude of 69,000 feet (21,000 meters), achieved with a pull-up at Mach 2.1, and climbing vertically above Mach 1. However, there would be no publicity for the YF-107's feat, since the Lockheed F-104 was concurrently performing speed and zoom climb flights in official pursuit of new records. Despite this, by early 1957 the strong performance of the YF-107 seemed to position it for a production order.
The F-105 incorporated an internal bomb bay, aimed at better positioning it to win budget monies in the then-ongoing Tactical Air Command fighter versus Strategic Air Command bomber rivalry. NAA, too, designed a semirecessed area in the 107's lower fuselage that fit a wide variety of external stores. Ironically, once in service the F-105's bomb bay would mainly carry fuel.
The Air Force terminated the NAA F-107 contract in March 1957, but the three prototypes continued test flying under the auspices of the National Advisory Committee for Aeronautics (now NASA) until August 1959.
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