In the meantime German engineers also took interest in jet propulsion systems. In 1908 Hans Holzwarth built a gas turbine featuring a system of valves, which allowed to control the pressure inside the combustion chamber. In the fall of 1933 a 22-year-old student of physics and aerodynamics at Göttingen University took a keen interest in the development of jet propulsion. His name was Hans Joachim Pabst von Ohain and he patented his first jet engine design on November 9, 1935. Von Ohain was a prolific engineer: one of his inventions (a method of recording a soundtrack directly onto cinematographic film) was purchased by Siemens, which gave the young scientist the financial independence to continue the development of his jet engine design.
Von Ohain’s powerplant consisted of a two-stage compressor, an annular combustor and a centrifugal turbine. Max Hahn, a master machinist working for Bartels und Becker in Göttingen was commissioned by von Ohain to build the first working model of his engine. This is how von Ohaim remembers the early days of testing the new design: “I knew from the start that I would have to take a very close look at the combustion process. I was also aware of the fact that the basic design would have to be continuously improved, which required time and money – and I had neither. Fortunately, professor Robert Pohl from the University of Göttingen came to my rescue. We had a very friendly chat and he told me he was absolutely convinced the jet propulsion was the way of the future. He also encouraged me to seek assistance within the industry and offered to provide me with a personal letter of recommendation. I intuitively felt that engine manufacturers would not show much interest in gas turbines, so I decided to go to Heinkel.”
In March 1936 von Ohain met with Ernst Heinkel and signed two documents: one was for the sale of rights to his patented jet engine design, the other a full-time employment contract. The first project that von Ohain completed for Heinkel was the HeS 1 hydrogen-burning powerplant developing 250 KG of thrust. The modified and improved version of the engine, the HeS 2, was ready in March 1937. Von Ohain now focused his efforts on designing a new combustion chamber, which would use liquid fuel in place of hydrogen. After it had been successfully tested the new combustor was incorporated into von Ohain’s new engine – the HeS 3b. The engine, weighing in at 360 kg, produced 500 KG of thrust at 13 000 rpm. The new design was then flight tested slung under the fuselage of a Heinkel He 118.
Now that a working jet engine had been successfully tested, work could begin on designing an aircraft that would be powered by the new design. The Heinkel He 178 was a shoulder wing monoplane with the cockpit placed well ahead of the wing’s leading edge. The HeS 3b powerplant was installed inside the duralumin fuselage with the air intake placed in the aircraft’s nose. The fuel tanks were installed behind the pilot’s seat. The conventional type landing gear featured narrow track main wheels, which were designed to retract into the fuselage wells.
![Wooden launch rails for 12 R4M rockets installed on Me 262’s underwing stations. [Visualisation 3d Marek Ryś]](images/nicewatermark/occnvai251messerschmitt-me-262-schwalbe-vol-icati95iti688limitstart3-04_mo46-me262sho1.jpg "Wooden launch rails for 12 R4M rockets installed on Me 262’s underwing stations. [Visualisation 3d Marek Ryś]")
At around 0500 on August 27, 1939 Erich Warsitz made history when he took off from Rostock-Marienehe airfield in the world’s first turbojet powered aircraft. The first flight did not last very long: after just one circuit over the field Warsitz had to bring the aircraft in following the landing gear malfunction and engine flameout.
The work on the HeS 3b continued and soon its successor was ready for testing. The HeS 8 (designated 109-001 in RLM documents) would be used as the powerplant in Heinkel’s new fighter design – the He 280.
In the meantime the executives at Junkers Flugzeugwerke AG also took interest in the design and development of turbojets. To that end Prof.Dr.-Ing. Herbert Wagner put together a small research team headed by his former assistant Dipl.-Ing. Max Adolf Müller. The team’s task was to design and build a turbojet powerplant at Magdeburger Werkzeugmaschinenfabrik, one of Junkers’ subsidiaries. The small team grew quickly and by the summer of 1936 over thirty engineers were directly involved in the project. When the design work on the new engine had been completed Müller and a group of his closest associates were approached by Ernst Heinkel and persuaded to “defect”. Indeed, in May 1939 Müller tendered his resignation and began to work for Heinkel the following month. The research that Müller’s team had carried out in Magdeburg was now used in the design of Heinkel’s HeS 30 turbojet (109-006 in official RLM documents), which featured an axial flow compressor.
In 1936 Dipl.-Ing. Anselm Franz, a 36-year-old graduate of Higher Technical School at Graz, was hired by Junkers-Motorenwerke to head their department of piston engine compressor systems and jet propulsion. In 1938 Prof.Dr.-Ing. Otto Mader, one of Junkers senior executives, approached Franz to produce a comprehensive survey of all research into gas turbine propulsion. Having studied the results of Müller’s work, Franz concluded that further development of the powerplants he had developed was pointless. “In 1939 the RLM wanted us to take over the development of Wagner’s engine, but I firmly rejected that option. In the fall we received an official government contract to develop our own turbojet design – the T 1, which later became known as Jumo 004 A. That engine could be considered the world’s first successful turbojet featuring an axial flow compressor. Its main design characteristics would become standard for all future turbojet powerplants. Jumo 004 was also the first mass produced turbojet and the first jet engine to be used in combat.
Unlike Ohain’s and Whittle’s centrifugal designs, the Jumo 004 was a pure axial turbojet, which was better suited for high speed flight thanks to its smaller frontal area. The engine’s main design features closely resembled those used in today’s turbojet powerplants.
Although the government requirements called for the new engine to produce 5.8 kN (600 kG) of thrust, we based our initial design work on a significant power reserve. The fact that we managed to obtain such good results in a relatively short period of time was quite a spectacular achievement, especially given that our work was truly pioneering and involved technology that was completely new and untested. Two key decisions that we made in the early planning stages clearly contributed to our final success. First of all, from the outset we rejected the idea of going for maximum performance numbers in order to build a working device as quickly as possible. This would allow us to run the necessary tests and to fine tune the engine’s development process based on the experimental results. The second key decision was to perform all compressor blade tests outside of Junkers, which greatly facilitated the test program and minimized risk level.”
The initial design work on the new engine began at Junkers in October 1939. One of the members of a thirty-strong team involved in the project was Fritz Böttger, who reported directly to Franz. The Jumo T 1 was ready by the spring of 1940 and the engine first test run was performed on October 11, 1940. By December 1940 the engine was first run at its maximum speed of 9 000 rpm. Another milestone was achieved in January 1941 when the T 1 delivered 430 kG of thrust. One of the recurring problems at that stage was excessive compressor blade vibrations, which almost led to a catastrophic failure of the engine. It took the project team six months of intense work to rectify the problem by replacing the light metal blades with heavier machined steel units. Another experimental version of the engine demonstrated the required thrust output of 600 kG on August 6, 1941. On December 22, 1941 the fifth T 1 prototype (004A) produced 1 000 kG of thrust during a ten-hour, continuous test run. However, the maximum thrust was achieved only momentarily when the engine was run at temperatures impossible to sustain under normal operating conditions. [...]
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