The HeS 30 was an early jet engine, originally designed by Max Adolf Mueller at Junkers, but eventually built and tested at Heinkel. It was possibly the best of the "Class I" engines, a class that included the BMW 003 and Junkers Jumo 004, but work on the design was stopped by the RLM, who felt the Heinkel team should put all their efforts into other designs. Note that the "official" name for the engine is the 109-006, and thus it would normally be known as the HeS 006, however development was ended just as these names were being written up at the RLM, and thus the HeS 30 name remains much more common.
Mueller had been working on a variety of engine designs at Junkers before 1938, when Junkers bought Junkers Motoren (Jumo), formerly a separate company formed primarily from the Siemens engine concerns. In October 1939 Junkers decided, under pressure from the RLM, that all engine work should take place at Jumo, who now had their own jet engine team in place. Mueller would have ended up in a subordinate role, and decided to leave instead. He and about half of the original Junkers team were scooped up by Ernst Heinkel and moved to his Rostock campus.
Of all of the designs Mueller brought with him, what would become the HeS 30 was the simplest and easiest to build. Mueller promised Heinkel that he could have the engine up and running on a testbed within one year of completing the move, a promise he was ultimately unable to meet. Mueller had in fact managed to built a test engine while still at Junkers, however it was only able to run at about half speed, and then only with continuous supply of external compressed air. The design was adbandoned when Mueller left, the Jumo team's simpler design being used instead.
Key to the engine's working cycle was an axial compressor of then-unique construction. Most German engines of the era had the stators do all of the actual compression, with the rotors speeding up the air for them to compress. In the HeS 30, the rotor and stators shared compression, about 50-50, a design originally provided by Rudolph Friedrich of Junkers. Overall the engine had a five-stage compressor providing air to ten flame cans, which powered a single-stage turbine. The turbine was also unique for the era, using a set of "guide vanes" that were adjustable for various operating speeds. Like most German axial engines, the overall design also relied on a variable exhaust cone and an electric starter motor.
Due to the move, it took considerable time for the team to restart work on the design, and even though three experimental engines were ordered as the 109-006 in 1939, it was not until May 1942 that the first engine actually ran. In addition to problems with working conditions, the compressor turned out to provide more mass flow than initially suspected, forcing a redesign of the turbine to better handle the air flow. In May, Mueller and Heinkel had an argument that led to Mueller quitting.
Work on the engine continued, and by October it was running at full power. Of all of the early engines, the HeS 30 was by far the best design. It produced a thrust of 860 kg, about the same as contemporary designs, but weighted only 390 kg, providing a much better power-to-weight ratio. The engine also had much better specific fuel consumption and was smaller in cross-section as well. It has been said that the overall performance was not matched until 1947.
Schelp, in charge of engine development at the RLM, refused to give Heinkel a production contract, an event that von Ohain claims nearly brought Ernst Heinkel to tears. Schelp noted that while the design was excellent, BMW and Jumo were so far ahead that they simply didn't need another "Class I" engine – something that would prove to be rather ironic in another two years. It also appears he had some misgivings about the compressor arrangment, but if this was the case it was never official.
Instead of "yet another" Class I engine, Schelp asked Heinkel to continue work on a "Class II" engine of about 1,300 kg thrust, which would be needed for reasonably sized single-engine fighters, as well as useful twin-engine bombers. Thus work on the HeS 30 ended, and Heinkel turned, gudgingly, to the Heinkel HeS 011, an excellent design which would not enter production before the war ended.
References
- German Jet Engine and Gas Turbine Development 1930-1945, Antony Kay, Airlife Publishing, 2002.