The Junkers Jumo 004, was the worlds first production turbojet engine in operational use, and the first successful axial compressor turbojet engine. Variants and copies of the engine were produced in Eastern Europe, the feasibility of jet propulsion had been demonstrated in Germany in early 1937 by Hans von Ohain working with the Heinkel company. The companies remained skeptical and little new development was carried out, in 1939 Schelp and Mauch visited the companies to check up on progress. Otto Mader, head of the Junkers Motorenweke division of the large Junkers aviation firm, stated that if the concept was useful. Schelp responded by stating that Dr Anselm Franz, then in charge of Junkers turbo- and supercharger development, Franz started his development team later that year, and the project was given the RLM designation 109-004. Franz opted for a design that was at once conservative and revolutionary, the axial-flow compressor not only had excellent performance, about 78% efficient in real world conditions, but it also had a smaller cross-section, important for high-speed aircraft. On the other hand, he aimed to produce an engine that was far below its potential, in the interests of expediting development. One major decision was to opt for a simple combustion area using six flame cans, Fedden himself criticized the attachment of the 004s compressor casing, which was in two halves, bolted to the half-sections of the stator assemblies. The first prototype 004A, which was constructed to run on fuel, was first tested in October 1940. It was benchtested at the end of January 1941 to a top thrust of 430 kgf, and work continued to increase the output, vibration problems with the compressor stators, originally cantilevered from the outside, delayed the program at this point. Max Bentele, as an Air Ministry consulting engineer with a background in turbocharger vibrations, the original aluminium stators were replaced with steel ones in which configuration the engine developed 5.9 kN in August, and passed a 10-hour endurance run at 9.8 kN in December. The first flight test took place on March 15,1942, the 004 used an eight-stage axial-flow compressor, with a number of axial combustion chambers, and a one-stage turbine with hollow blades. On July 18, one of the prototype Messerschmitt Me 262s flew for the first time under jet power from its 004 engines, Franz realized that the Jumo 004 would have to be redesigned to incorporate a minimum of these strategic materials, and this was accomplished. The engines operational lifespan was shortened, but on the side it became easier to construct. Production engines had a cast magnesium casing in two halves, one with half-sections of stator assemblies bolted to it, the four front stators were constructed from steel alloy blades welded to the mount, the rear five were pressed steel sheet bent over the mount and welded on. Steel alloy compressor blades dovetailled into slots in the disk and were fixed by small screws. The compressor itself was mounted to a shaft with twelve set screws. A hole in the nose of the intake diverter body contained a pull-handle for the cable which turned-over the piston engine
Cutaway example of a Junkers Jumo 004 jet engine at the National Museum of the U.S. Air Force, Wright-Patterson AFB, Ohio.
Frontal view of a Jumo 004 engine mounted in a nacelle on an Me 262 fighter. The pull-starter handle for the Riedel APU unit to start the 004 is clearly visible in the center of the engine's intake diverter.
Sectioned Jumo 004 exhaust nozzle, showing the Zwiebel restrictive body