FLIGHTLINE: 202 - NORTHROP MX-324/334 AND XP-79
Skyfire77 last edited by
-Three-quarter view of XP-79B (s/n 43-52437) at Muroc AAF in 1945. | Photo: USAF
FLIGHTLINE: 202 - NORTHROP MX-324/334 AND XP-79
Developed in WWII, the Northrop XP-79 was was designed using bleeding edge technology and aerodynamic concepts, but only flew once.
Early in WWII. the US was facing unknown, possibly overwhelming odds in the fight against the Axis Powers. As part of a push for innovative designs using as little strategically valuable materials (chiefly aluminum and steel) as was possible, Jack Northrop conceived of an interceptor constructed using magnesium, powered by a rocket engine, and with the pilot in a prone position to better withstand high g-forces. The US Army Air Forces was interested enough to award a contract to build three glider demonstrators, which Northrop designated the N-12 and which the USAAF called the MX-334.
-The Northrop N-12/MX-334 glider, used as proof-of-concept for the flying wing interceptor. | Illustration: Nortrop Corp.
The first glider, a completely tailless design, was completed in Spring 1943 and was shipped to the NACA Langley center for testing in their wind tunnel. Testing indicated that the 334 was unstable at high speed, and so a wire-braced vertical fin was added to the second and third aircraft. Initial tow tests were carried out behind an unknown model of Cadillac, but the car lacked the needed power. Changes were made to the glider, and on 4 September 1943 it took off on its maiden flight behind an Army truck. More comprehensive testing began on 2 October, with the MX-334 being towed behind a P-38. Testing continued with both the #2 and #3 aircraft, although #3 was written off after test pilot Harry Crosby lost control of the glider after it entered the prop wash of the P-38.
-One of the MX-334 gliders, with the additional tail fin in place. | Photo: Northrop Corporaton
Early in 1944 the #2 aircraft was fitted with an Aerojet XCAl-200 rocket motor, which was rated at 2,000lbf thrust. This conversion changed the aircraft's designation to MX-324, which was the "secret" code number used for the rocket powered model. The maiden flight of the modified MX-324 was on 5 July, making the craft first American rocket-powered airplane to fly. The Aerojet engine, fueled by mono-ethylaniline fuel and red fuming nitric acid, proved to be unsuitable however, and testing was ended on 1 August, with the first and second aircraft being scrapped shortly thereafter. As a result of the test program and the subsequent failure of the XCAL-2000 engine, the design for the XP-79 was altered to replace the rockets with two Westinghouse 19B axial-flow turbojets of 1,150lbf thrust each.
-The MX-324 under rocket power during its first flight. | Photo: USAAF
The USAAF canceled the contract for the two rocket-powered XP-79, retroactively called the A model, and provided funds to convert the third prototype to jet power, with the aircraft now designated the XP-79B. Given the serial number 43-52437, the plane was fabricated from welded magnesium monocoque structure. The alloy, light but strong, had not been used in this quantity before, and Northrop faced challenges during the development of the XP-79 in learning to weld the metal. Jack Northrop, seeing reports of the damages inflicted on Allied fighters by Axis bombers, designed the aircraft to withstand a great deal of punishment, with skin thickness ranging from 0.75in on the leading edge to 0.125in on the tailing edge. This heavy duty construction has led to later accounts of the XP-79 being designed to ram enemy aircraft, but this is in error. Such a maneuver would be very difficult, and even with the exceptionally strong structure would likely result in the loss of both aircraft. Instead, production P-79Bs would be armed with a quartet of .50 Browning M2 machine guns.
-Orthograph of the XP-79B. | Illustration: Northrop Aircraft
The P-79 was 14 feet long, with a wingspan of 38 feet and a height of just over 7.5 feet. The plane weighed 5,842lbs empty, and max weight was 8,669lbs. The twin 19B engines would propel the plane to an estimated cruise speed of 480mph and a max speed 547mph. The unique design of the aircraft resulted in the landing gear being made up of four legs instead of the usual tricycle arrangement, with the oleos retracting into the wings. The pilot lay prone between the two jet engines, with intakes fared into the wing leading edge, and twin rudders mounted above the exhausts. As a traditional control stick would not work with the pilot's prone position, a tiller bar and rudder pedals were provided. Adding to the unusual features of the P-79, the split ailerons had bellows-boosting, fed by intakes positioned just below the jet inlets. As was common with early jets, range was limited, with endurance limited to just 2.5 hours, and a range of about 1,000 miles. The thrust provided an exceptional climb rate of 4,000fpm however, and a max ceiling of 40,000 feet.
-The XP-79B on the dry lakebed at Muroc AAF. | Photo: USAAF
-Head-on picture of the XP-79, showing the very unusual pilot's position, landing gear arrangement and inlets. | Photo: USAAF
The XP-79B was rolled out early in 1945, after which it was transferred to the Army Air Force's Muroc testing site in June. High speed taxi tests resulted in a series of burst tires, delaying further testing while stronger tires were sourced. Finally on 12 September 1945 the XP-79B was readied for its maiden flight, with Harry Crosby at the controls. The test flight proceeded normally for the first 15 minutes, until during a slow roll Crosby lost control for reasons unknown. As the nose dropped the roll continued, with the plane entering a vertical spin. Crosby attempted to bail out, but he was hit by the plane's wing and knocked out, resulting in his death. The XP-79 struck the lakebed and burst into flames, completely destroying the aircraft.
-The XP-79 on its sole flight. | Photo: USAAF
Although a second XP-79B (s/n 43-52438) was under construction, the USAAF saw no future in the design, and canceled further work. The incomplete aircraft was later scrapped, ending this chapter of Northop's experimentation with flying wings
Chariotoflove last edited by
@skyfire77 I like to think Jack Northrop would have been a BG fan.
krustywantout last edited by
@skyfire77 Sad. The courage that test pilots have is just extraordinary. I also have a great appreciation for the early automotive racers who were also driving on the edge of death every time they went out.
BaconSandwich last edited by
Have there been any other aircraft (other than Wright brothers era) where the pilot lies prone?
Skyfire77 last edited by
@baconsandwich A few, mostly during or right after WWII.
The Brits built two, the Meteor F.8 "Prone Pilot":
and the Reid and Sigrist R.S.4 "Bobsleigh:
The Nazi's tried with the Hs 132, but none of the four built ever flew.
And the US tried again with the EF-80:
Needless to say, none of these experiments resulted in anything useful.
ttyymmnn last edited by
The boom operator in the KC-135 lies down, but that's only because there's no room to sit up. You have to rest your head on a chin rest. Still has to be hard on the neck.
Urambo Tauro last edited by
@ttyymmnn Laying down, passing gas, and getting paid for it... what a gig!