Heinkel He 178

The Heinkel He 178 was the world's first aircraft to fly under turbojet power, and the first practical jet aircraft. It was a private venture by the German Heinkel company in accordance with director Ernst Heinkel's emphasis on developing technology for high-speed flight and first flew on 27 August 1939, piloted by Erich Warsitz. This had been preceded by a short hop three days earlier.

Development
In 1936, a young engineer named Hans von Ohain had taken out a patent on using the exhaust from a gas turbine as a means of propulsion.

He presented his idea to Ernst Heinkel, who agreed to help develop the concept. Von Ohain successfully demonstrated his first engine, the Heinkel HeS 1 in 1937, and plans were quickly made to test a similar engine in an aircraft. The He 178 was designed around von Ohain's third engine design, the HeS 3, which burned diesel fuel. The result was a small aircraft with a metal fuselage of conventional configuration and construction. The jet intake was in the nose, and the plane was fitted with tailwheel undercarriage. The main landing gear was retractable, but remained fixed in "down" position throughout the flight trials.

The high-mounted wooden wings had the characteristic Günter brothers elliptical trailing edge. Photos showing a "straight wing" (straight-line-taper in the wing planform, for both the leading and trailing edges) were of the second prototype He 178 V2, which never flew under power.

The aircraft made its maiden flight on 27 August 1939, only days before Germany started World War II by invading Poland. The pilot was Erich Warsitz, who had flown the world's first rocket powered airplane, the Heinkel He 176, on its maiden flight in June 1939, only months before.

The aircraft was a success; however, speeds were limited to 598 km/h at the proposed service altitude, and combat endurance was only 10 minutes.

Heinkel had developed the turbojet engine and the testbed aircraft, the Heinkel 178, in great secrecy. They were kept secret even from the German air force and the Reichsluftfahrtministerium. On 1 November 1939, after the German victory in Poland, Heinkel arranged a demonstration of the jet to officials. Herman Goering, commander in chief of the German air force, didn't even show up. Ernst Udet and Erhard Milch watched the aircraft perform, but were unimpressed. Nevertheless, Heinkel was undeterred, and decided to embark on the development of a twin-engine jet fighter, the He 280 as a private venture using what had been learned from the He 178.

The He 178 was placed in the Berlin Air Museum, where it was destroyed in an air raid in 1943.

Significance
Ernst Heinkel was disappointed by the lack of official interest in his private-venture jet. In his autobiography, he attributes this to the failure of the leaders of the Reichsluftfahrtministerium to understand the advantages of jet propulsion and what breakthrough the He 178 represented. Similar claims are common in literature on Heinkel, and were made on the previous version of this page. However, the reason the Reich Air Ministry was not interested, was because it was developing jets itself. Nobody at Heinkel knew anything about these secret military projects.

In 1939 BMW and Junkers were working on "official" turbojet engines for the German airforce. As these were axial-flow turbojets, not radial-flow turbojets like those being developed at Heinkel and by Frank Whittle in England, they promised much higher flight speeds.

In mid September 1939, two weeks after Germany started World War II, the German air force ordered aircraft manufacturers to reduce development work and concentrate all efforts on winning what German officialdom expected to be a short war. But the development of jet powered single-seaters was ordered to continue, to get such aircraft operational as fighters as soon as possible.

In July 1944 both the German and British air forces began flying jet powered fighters operationally. The British Gloster Meteor F.I, powered by Rolls-Royce Welland radial-flow turbojets, had a maximum speed (in level flight and at optimum altitude) of 430 mph (668 km/h). This was about the same as piston engined fighters being flown in combat at that time. The German Messerschmitt Me 262, powered by Junkers Jumo 004 axial-flow turbojets, had a maximum speed of 540 mph (870 km/h), 100 mph faster than the best piston engined fighters. It also had superior climb performance. On the downside the engines had a service life of about 25 hours whereas the British ones could run for 180 hours. The Luftwaffe flew the Me 262 in combat as an air-superiority fighter. The RAF used the Gloster Meteor for interception of V-1 flying bombs, coastal patrols and for training, where its ability to reach speeds of over 500 mph in a dive could simulate attacks by German jets.