Jagdflugzeuge mit Strahltriebwerk
The first contest Jagdflugzeuge mit Strahltriebwerk (January 1939)
Bench tests and impressive theoretical performance figures convinced the RLM that it was time to begin the development of Germany’s first jet-propelled fighter in 1938. But which firm would design and build it?
H
ans Joachim Pabst von Ohain began theoretical work on gas turbine propulsion in 1933 aged 22, unaware that similar research had been started by Frank Whittle in Britain three years earlier. The following year, Dr Herbert Wagner of Junkers undertook some private research into the possibility of a turboprop engine and thereby began work on his own independent turbojet design. The following year, he was made his company’s head of special developments and started examining design features for a transatlantic airliner. Von Ohain’s turbojet received a German patent on November 9, 1935, and the first model of it was constructed. He met Dr Ernst Heinkel at his home in Warnemünde, a district of Rostock, in March 1936 and the aviation firm boss agreed to both give him a job and pay him royalties on his design.
The following month, having realised that conventional aero engines would be unable to provide the performance his airliner required, Wagner formed a research team led by Max Adolf Müller to work on turboprops – where a gas turbine, rather than a piston engine, is used to drive a propeller. The first Heinkel demonstration jet engine, von Ohain’s HeS 1, was completed by February 1937 and ran successfully a few days later. This caused great excitement within the company and Dr Heinkel ordered that the turbojet programme be accelerated. In August 1937, aeronautical engineer and gas turbine research enthusiast Helmut Schelp was appointed master of aircraft engineering in the research department of the RLM’s Technisches Amt or ‘Technical Office’. He was, at this point, unaware that any practical turbojet units were already being developed.
The design of a practical liquid-fuelled flight engine at Heinkel, the HeS 3b, was frozen during the summer of 1938, while Müller’s team began bench testing an engine derived from their turboprop – a turbojet. A few months later, Schelp approached the four main aero engine builders – Daimler-Benz, Junkers Motoren (Jumo), BMW and Bramo – and encouraged them to consider the development of gas turbine powerplants. Daimler-Benz initially refused but the other three accepted research contracts from the RLM. A meeting of the Lilienthal Society for Aviation Research held in Munich on August 23-24, 1938, had the theme of ‘airframes and powerplants’ and was attended by 90 specialists from across the German aviation industry. One of the principal lectures was Gas Turbines as the Principal Powerplant for Aircraft by Professor Karl Leist of the DVL’s Institute for Powerplants. While this focused primarily on turboprops, pure turbojets were also discussed. One of the main problems with turbojets at this time was the lack of a sufficiently efficient compressor. The simple centrifugal type used by von Ohain – and also by Whittle – required a larger frontal area and created more drag. This problem was solved by Walter Encke, the head of the Institute for Aerodynamic Machinery, part of the Aerodynamic Research Institute (AVA) at Göttingen. He designed a highly efficient axial compressor, where the blades acted as aerofoils and were arranged in stages to maintain the correct pressure. The axial flow compressors used in the first working turbojets produced under RLM contract by both BMW and Junkers were designed by Encke – enabling both engines to be slender and lightweight compared to their British counterparts, produced by Whittle’s firm Power Jets. BMW started work on its first jet engine in 1938 under head of research Dr Kurt Löhner but the design his team produced had a centrifugal compressor and it was cancelled with the outbreak of war so that resources could be concentrated on the BMW 801 radial piston engine. Meanwhile, Bramo had started work at the same time but its design for a counter-rotating axial flow turbojet was more promising. Bramo merged with BMW in late 1938, however, and its turbojet became the BMW P.3302 – eventually to become the BMW 003. LEFT: Heinkel got a head start in the jet race by hiring young inventor Hans Joachim Pabst von Ohain who had begun theoretical work on gas turbine powerplants in 1933, aged just 22. via author