Northrop MX-324
| Northrop MX-324 | |
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 MX-324 at Muroc Army Air Field |
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| Type: | Experimental airplane |
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The Northrop MX-324 was an experimental aircraft made by the US manufacturer Northrop Aircraft Inc. from the first half of the 1940s. Designed as a pure flying wing aircraft , it also received a vertical stabilizer for flight tests.
history
The company Aerojet Engineering developed between 1941 and 1942 to the JATO -Triebwerk 12AS-1000 D-1 with solid driving and a liquid rocket engine. Aerojet used the spontaneously reacting substances monoethylaniline and red fuming nitric acid as oxidizing agents. After the first test bench runs in February 1942, the development initially also went in the direction of a JATO booster pack (starting aid for aircraft). Shortly thereafter, however, the XCALR-2000A was also released, a version with adjustable thrust that used a total of four combustion chambers (2 × 3.3 kN and 2 × 1.1 kN). The four combustion chambers were placed at a slight incline on a horizontal shaft and could rotate as a unit and thus use the centrifugal forces as a pump.
On September 15, 1942, Northrop proposed a brushless rocket plane to the US Army Air Force. The earliest ideas were to develop a loss interceptor for object protection (Model 14). When the rockets were burned out, an explosive charge was supposed to destroy the machine and the pilot was supposed to return by parachute jump. The concept envisaged a lying position for the pilot, as it was known that this way higher centrifugal forces could be endured when maneuvering. In this way it was also possible to minimize the size of the front and side surfaces and the probability of hits by enemy gunmen. The machine should reach a top speed of 540 mph and an altitude of 40,000 feet in 6.1 minutes. With the support of his friend Theodore von Kármán , Northrop managed to get General Arnold to show interest in this unusual concept. Since the Northrop plant was already busy with the fulfillment of other orders, the USAAF decided to carry out the development "in-house" on the Wright Field.
The Materiel Division as principal appeared the design so radical that they insisted first three MX-324- mock-ups to be made of wood and use for wind tunnel and flight tests. So enough data should be collected with the least possible technical risk. Despite the full capacity utilization of the main plant, Northrop was able to carry out this woodwork itself.
The contract awarded in September 1942 comprised the construction of a rocket-propelled MX-324 and two MX-334 glider planes without propulsion. With the Aerojet XCALR-200, the MX-324 received a simplified version of the XCALR-2000A-1, which only had one combustion chamber and delivered 0.9 kN (200 lbf) of thrust. The engine could not be regulated and burned for five minutes. Plywood was used as the main material for the airframe in all cases. However, the central part of the fuselage that bears the greatest loads was manufactured as a welded tube construction.
The first MX-334 flew for the first time on October 2, 1943 at Muroc Army Air Field with test pilot John Myers at the controls. The MX-324 followed on November 30, 1943 (or August 27, 1943) with an unpowered glide flight. The first flight with rocket propulsion took place on July 5, 1944 after the machine was towed by a P-38 to an altitude of 8,000 ft. And disengaged there. Pilot Harry Crosby ignited the engine for a four-minute flight, making the first rocket flight by a US aircraft. The weak engine only served to extend the gliding flight, so the altitude could not be maintained after the release. The first test flights at higher speed showed the instability of the chosen flying wing design, so that a tail fin made of plywood was additionally installed.
The MX-324 performed eight glide flights and seven powered flights by July 27, 1944. The two MX-334 completed a total of 13 flights by May 19, 1944, each lasting five to eight minutes and reaching 480 km / h (300 mph). A towing machine had to be used for ascent for all flights.
While the MX-334 was still being tested, the Army was negotiating with Northrop to build a prototype for a full-scale, all-metal interceptor. However, it was clear from the start that all design and production services had to be subcontracted. This aircraft was to be powered by an 8.9 kN (2000 lbf) XCALR-2000A-1 and two additional RATO boosters, each with 4.5 kN of thrust. A maximum speed of 860 km / h at an altitude of 6100 m and a peak altitude of 12,200 m were calculated as performance values. In January 1943, the Army placed the order for three XP-79 with the project number MX-365 to Northrop.
Details of the MX-324 were not made public until February 12, 1947, over 16 months after the project was discontinued.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 1 |
| length | 3.45 m |
| span | 10.98 m |
| Wing area | 23.4 m² |
| Takeoff mass | 1200 kg |
| Engines | an Aerojet XCALR-200 with 0.9 kN thrust (MX-324) MX-334 without drive |
See also
literature
- Bill Norton: US Experimental & Prototype Aircraft Projects Specialty Press, 2008, ISBN 978-1-58007-109-3 , pp. 247 f.
- Dennis R. Jenkins, Tony R. Landis: Experimental & Prototype US Air Force Jet Fighters , Specialty Press, 2008, ISBN 978-1-58007-111-6 , p. 32 f.
Web links
- NASA report on the wind tunnel investigations of the MX-334 (accessed August 3, 2014)
Remarks
- ↑ The abbreviation "MX" (for Materiel, Experimental) was given from the beginning of 1941 to 1950 by the Experimental Engineering Department of the US Army Air Corps Materiel Division (shortly thereafter Army Air Forces Materiel Command) for many of their research and development projects . MX numbers were generally assigned to a project very early on, so that many project numbers did not lead to a product, but only to a research report.
Individual evidence
- ^ Bill Norton: US Experimental & Prototype Aircraft Projects , p. 248