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
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Comments (15)
So Skyfire, at the end of the war the US grabbed certain technologies from Germany. Do you think the Horton wing was one of those technologies? And do you think it was developed further? AND is it possible that such a development was what Kenneth Arnold saw when he was flying and saw the "flying saucers"? The drawings, probably sketch artist, of what he saw look mighty similar to the Horton with it's tail section attached.
I've always had this on my mind but never had the opportunity to discuss it with anyone who is familiar with aircraft of the time. This aircraft is the US analog to the Horton which leads to my question.
The Ho 229 (also called the H.IX)? It's public knowledge that Operation PAPERCLIP grabbed the third prototype and brought it here for examination. It doesn't seem likely that it was ever finished, and was placed into storage at the...
Read moreThat's essentially what I was thinking. The event took place in Washington State.
Yup, delta wing design proved rather difficult to perfect. The big nuclear bombers us Brits produced were delta designs, but one can immediately see that the swept back wings are not uniformly formed along their length... for all sorts of complicated reasons (my explanation for what I don't understand), and later, the Concorde wings were similarly not uniformly formed.
My understanding is that a pure delta wing is inefficient at low speeds and also introduces some control issues, so one of the solutions is to vary the sweep across the wing, that way you get the benefits of the delta at high speed but gain back...
Read moreOnce I saw the flying wing design I knew the program was cancelled for crashes. Legendarily unstable.
I wonder how much of the horton brothers work, and the whittle engine, and the messcherschmidt designs the us was aware of and when
Jack Northrop knew of the Hortons, IIRC, but it wasn't until after the war, when PAPERCLIP, LUSTY and the other Allied programs to keep Nazi planes, research, and workers out of Soviet hands, that we found out the details.
Hap Arnold was...
Read moreIt almost looks like the ligth jets from Tron: Legacy lmao.
Somewhat, though it's more the prone position than anything else. The Light Jets have straight, tapered wings rather than the P-79's quasi-delta shape.
You are right! (Finially someone that watches Tron lmao)