Encyclopedia Astronautica
XP-79


American manned rocketplane. Flown in 1945. The XP-79 was Jack Northrop's design for a rocket-propelled flying wing fighter.

It was also known as the 'flying ram' since the original concept was for the pilot to destroy enemy bombers by slicing through them. Another unique aspect was the rotating 'Aerotojet' XCALR-2000A-1engine design (the more conventional XCALT-6000 was an alternative). Delays in engine development meant the first prototypes were equipped with turbojet engines. After the test pilot was killed in the first flight, the project was abandoned.

Northrop XP-79B by Joe Baugher

The Northrop XP-79 originated in 1942 as an idea by John K. Northrop for a high-speed flying wing fighter aircraft powered by a rocket engine. Near-sonic speeds were envisaged. The idea was somewhat similar to that which eventually produced the Messerschmitt Me 163 rocket-powered interceptor in Germany.

The Northrop fighter project was to be powered by a 2000 pound thrust Aerojet XCALR-2000A-1 rocket engine, with takeoff assisted by a pair of 1000 pound thrust rocket boosters which would be dropped after takeoff. Northrop proposed that this airplane be flown by a pilot lying prone in the cockpit, since it was hoped that this would reduce strain on the pilot during violent maneuver and would present a minimum silhouette to enemy gunners.

In January of 1943, the USAAF issued a contract for three prototypes under the designation XP-79. The availability of jet engines led to a decision in March to use two Westinghouse 19-B turbojets in the third prototype, which was redesignated XP-79B.

Since the layout of the fighter was so radical, it was thought that test glider prototypes be built to verify the validity of the concept. One of these was designated MX-324, and was fitted with a fixed tricycle landing gear. The MX-324 was towed into the air by a P-38 on July 5, 1944, and became the first American-built rocket-powered aircraft to fly.

Delays in the development of the Aerojet rocket engine caused the USAAF to cancel the two XP-79s, leaving only the XP-79B. The serial number of the XP-79B was 43-52437. The XP-79B was finally ready for flight testing in the summer of 1945. The pilot lay prone in an unpressurized cockpit situated between the two turbojets. The flying wing was of semimonocoque construction and was built largely of magnesium in order to save weight. Instead of conventional ailerons, the wing had air intakes at the tips for lateral control, in much the same manner as the XP-56. The aircraft was equipped with a pair of vertical tails, presaging the MiG-25 and the F-15. The retractable landing gear consisted of four wheels, two each in tandem. The XP-79B was to use a rather unusual technique for destroying enemy aircraft. The wing leading edge was reinforced so that it could slice off the wings or tails of enemy aircraft by ramming them! And if that didn't work, the XP-79B was equipped with a more conventional armament of four 0.50-inch machine guns in the wing leading edge.

The XP-79B was transferred to Muroc Dry Lake in June of 1945. Flight testing was delayed by problems with bursting tires during ground taxiing trials. On September 12, 1945, test pilot Harry Crosby finally took the XP-79B up in the air for the first time. It flew all right for about fifteen minutes, but the plane then suddenly went into a spin from which it proved impossible to recover. Crosby attempted to parachute to safety, but his chute failed to open and he was killed. The XP-79B impacted in the desert and was destroyed in the resulting fire. Magnesium burns very nicely. :-).

Although the mishap that cost Harry Crosby his life could have been corrected, the USAAF decided to abandon the project.

Specification of the XP-79B: Powered by a pair of 1365 lb. st. Westinghouse 19B turbojets. Wingspan was 28 feet, length 14 feet, and height was 7 feet. Wing area was 278 square feet. Gross weight was 8669 pounds. Estimated performance included a maximum speed of 547 mph at 20,000 feet, an initial climb rate of 4000 feet, a service ceiling of 40,000 feet, and a range of 993 miles. The proposed armament of four 0.50-in machine guns was never fitted.

Sources:

American Combat Planes, Ray Wagner, Third Enlarged Edition, Doubleday, 1982.

The American Fighter, Enzo Angelucci and Peter Bowers, Orion Books, 1987.

Gross mass: 3,930 kg (8,660 lb).
Thrust: 9.12 kN (2,050 lbf).

More... - Chronology...


Associated Countries
Associated Engines
  • 300LR-200 Aerojet Nitric acid/Amine rocket engine. XP-79 Launch thrust .882 kN. Development begun January 1943. Planned successor to XCALT-6000, developed under 'Project X' for the Northrop XP-79 Flying Wing rocket fighter. First flight 1945. More...

See also
Associated Manufacturers and Agencies
  • Northrop American manufacturer of rockets and spacecraft. Northrop, USA. More...

Associated Propellants
  • Nitric acid/Amine Drawing on the German World War II Wasserfall rocket, nitric acid (HNO3) became the early storable oxidiser of choice for missiles and upper stages of the 1950's. To overcome various problems with its use, it was necessary to combine the nitric acid with N2O4 and passivation compounds. These formulae were considered extremely secret at the time. By the late 1950's it was apparent that N2O4 by itself was a better oxidiser. Therefore nitric acid was almost entirely replaced by pure N2O4 in storable liquid fuel rocket engines developed after 1960. Early storable rocket systems sought to improve ignition characteristics and perforamance by eliminating the kerosene portion of the fuel. An amine is an organic compound produced when one or more hydrogen atoms of ammonia is replaced with organic groups. Mixed amine fuels were first developed by the Germans in World War II. TONKA-250, developed for the Wasserfall rocket, was used by the Russians after the war in various engines under the specification TG-02. More...

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