JUNKERS JUMO 004

The Messerschmitt Me 262 was the most important secret weapon of the Luftwaffe in their efforts of air combat superiority. Although often viewed as a last ditch super weapon, the Me 262 was already being developed as project P.1065 before the start of WWII. Plans were first drawn up in April 1939.

Me262

The first test flights began in April 1941, but since the BMW 003 turbojets were not ready for fitting, a conventional Junkers Jumo 210 engine was mounted in the nose, driving a propeller, to test the Me 262 VI airframe. When the BMW 003 were finally installed the Jumo was retained for safety which proved wise as both 003’s failed during the first flight and the pilot had to land using the backup piston engine. The V3 third prototype airframe became a true “jet” when it flew on 18 July 1942 in Leipheim near Günzburg, Germany, piloted by Fritz Wendel. This was almost nine months ahead of the British Gloster Meteor’s first flight on 5 March 1943. The 003 engines, which were proving unreliable, were replaced by the newly available Junkers Jumo 004.

The Junkers Jumo 004 was the world’s first turbojet engine in production and operational use, and the first successful axial compressor jet engine ever built.

The development of the Jumo 004 was based on the Magdeburg experiments. This development was continued by Franz Anselm at the Otto-Mader-Werke since 1939. Anselm used several existing components to built the Jumo 004. The compressor was built from an 8 stage axial construction of the AVA Gottingen. The turbine blades were developed by AEG.

On the 11 October 1940 the first static test run of the engine was performed. A total of 80 experimental Jumo 004A engines were built. The first flight was performed on 15 March 1942 onboard the Messerschmitt Me 110 and on 18 July 1942 the first Messerschmitt Me 262 was equipped with the new engine. The first preproduction series was the Jumo 004A-0. This engine was used for extensive flight tests, which were not satisfactory due to material overload and failure of the fan blades.

In summer 1941 redesigned 004A entered serial production as Jumo 004B-1. The first engines were ready in early 1942 and underwent intensive tests during 1943. The Jumo 004B differed with the compressor entry, an improved stator blade design for the compressor, modified turbine entry and separate compressor discs. Also hollow turbine blades were introduced, which caused again blade failures. In summer 1943 the serial production of these engines was started at Junkers Leipzig and at the Opelwerke at Russelsheim. A total of 7916 Jumo 004B were built by Junkers Flugzeugwerke plus an unknown number of engines at Opel.

Several improved series were designed up to the end of the war:

  1. Jumo 004-C had increased thrust, auxiliary fuel injection and afterburner. This series was only on sketch, none was built.
  2. Jumo 004-D with regulator for throttle movement and two stage fuel injection. Prototypes were built and tested, serial production began shortly before end of WWII.
  3. Jumo 004-E was D-series engine with a shorter tail pipe and a double tube, as well as an afterburner. This engine was developed for getting a better altitude performance. At the end of the war several test engines were ready and serial production was planned for summer 1945.

After the war the Jumo 004 was used by the Czech Air Force, which used the engine in the Avia S-91 and CS-91 produced by Avia. These Jumo 004 engines were produced at CKD at Prague.

The Soviet forces captured several engines and documentation at Dessau. The Jumo 004 was further developed and became the RD-10 which was fitted in the Jak-15, La-150 and Su-9.

In France the Jumo 004 and BMW 003 were studied and fitted into the Sud-Est S.O. 6000 “Triton” and the Arsenal VG-70.

The Junkers Jumo 004 is often remembered as a temperamental and failure-prone powerplant. Despite its advanced design, engine life was only between 10 and 25 hours, with the mean being at the lower end of this range. These failures were anticipated to some extent and the Me 262 was designed to permit extremely rapid engine changes.

Contrary to popular belief, the 004A was a fairly sound performer when premium steels were used, and early versions were known to achieve a 200-250 hour service life. However, the diversion of critical materials into U-boat production and other projects late in the war forced Junkers to produce the 004B model with only 1/3 of the high grade steel that had been used in the 004A. It was to be a disastrous concession for the Me 262.

The introduction of inferior metals compounded an already problematic situation with the turbine blade design. These blades were rigidly mounted, contributing to severe root stress relief problems. The weaker metals simply could not withstand this kind of abuse and regular compressor failures were an inevitable consequence.

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