Nazi Germany (1939)
Experimental jet-engine powered aircraft – 2 prototypes and 1 mockup

The He 178 has the honor to be the first aircraft that made it to the sky solely powered by a jet engine. It was mainly designed and built to test the new jet engine technology. Two would be built, of which the first prototype made its maiden flight in late October 1939, just weeks after the start of the Second World War.

Early German jet engine development

The leading German scientist in jet engine development was Hans Joachim Pabst von Ohain. He began working on jet engine designs during the thirties, and by 1935 managed to patent his first jet engine while working at the University of Göttingen. The following year, the director of this University, seeing the potential of the Hans Joachim jet engine, wrote a letter to Ernst Heinkel (the owner of the Heinkel aircraft manufacturer). Ernst Heikel was very interested in the development of jet-powered aircraft, seeing they had the potential of achieving great speed and range. After a meeting with Hans Joachim (17th March 1936), Ernst immediately employed him and his team (led by a colleague named Max Hahn) to work for his company.

In 1936, Hans Joachim and his team began building the first working prototype jet engine, using hydrogen gas as the main fuel, the HeS 1 (Heinkel-Strahltriebwerk 1). The HeS 1 was not intended as an operational engine, but for testing and demonstration purposes only. It was built and tested in early 1937, and was considered successful, so the research continued. The HeS 2 was the second test jet engine that initially used hydrogen gas fuel, but this would be changed to gasoline fuel. While this engine had some issues, it helped Hans Joachim and his team in gaining important experience in this new technology.

In September 1937, a series of modifications were made in order to improve its performance. By March 1938, the third HeS 3 jet engine was able to achieve 450 kg (1,000 lbs) of thrust during testing, much lower than the estimated 800 kg (1,760 lbs). Further modifications of the HeS 3 jet engine would lead to an increase of only 45 kg (100 lbs) of thrust.

Experimenting with the HeS 3 engine mounted on the He 118

In May (or July depending on the source) of 1939, testing of the improved HeS 3A engine began. At the same time, field testing done by attaching this engine to a piston-powered aircraft was being planned. For this reason, an He 118 was equipped with this auxiliary test jet engine. The He 118 was Heinkel’s attempt to build a dive bomber, but the Junkers Ju 87 was chosen instead. Having a longer undercarriage, the He 118 was able to mount the jet engine without any major problem. In order to keep the whole flight testing a secret, the tests were scheduled to start early in the morning.

The pilot chosen for this test flight was Erich Warsitz. When the He 118 reached the designated height using the piston engine, the pilot would then activate the auxiliary jet engine. During this flight, the He 118 powered by the HeS 3A jet engine managed to achieve 380 kg (840 lb) of thrust. More test flights were carried out with the modified He 118 until it was destroyed in a fire accident during landing. Despite this accident, the final version of the HeS 3B jet engine was intended to be mounted in the Heinkel designed He 178 aircraft. While this engine was far from perfect and did not manage to achieve the designer’s expected thrust, Ernst Heinkel urged its installation in the He 178 as soon as possible.

The He 178 history

Interestingly, the whole He 178 development began as a private venture. It was also under the veil of secrecy and the RLM (Reichsluftfahrtministerium), the German Aviation Ministry, was never informed of its beginning. Ernst Heinkel gathered the designers and technical directors to reveal to them ’…We want to build a special aircraft with a jet drive! The RLM is not to know anything about the 178. I take full responsibility!..’

Heinkel was possibly motivated by a desire to get an early advantage over the other German aircraft manufacturers. The main competitor was the Junkers Flugzeugwerke, which would also show interest and invest resources in developing this new technology.

While Hans Joachim was in charge of developing the proper jet engine, work on the He 178 airframe was led by the team of Hans Regner as main designer and Heinrich Hertel, Heinrich Helmbold, and Siegfried Günter as aircraft engineers. The first He 178 mockup was ready by the end of August 1938. Ernst Heinkel was, in general, satisfied with the design, but asked for some modifications of the cockpit and requested adding an emergency escape hatch door for the pilot on the starboard side. The following year, both the He 178 airframe and the HeS 3B jet engine were ready, so the completion of the first working prototype was possible.

Technical characteristics

The He 178 was designed as a shoulder wing, mixed construction, jet engine-powered aircraft. As it was to be built in a short period of time and to serve as an experimental aircraft, Ernst Heinkel insisted that its overall construction should be as simple as possible. It had a monocoque fuselage which was covered with duralumin alloy. The wings were built using wood and were sloping slightly upwards. The wing design was conventional and consisted of inboard trailing edge flaps and ailerons. The rear tail was also made of wood. The pilot cockpit was placed well forward of the wing’s leading edge.

The jet engine used initially was the HeS 3B, but this was later replaced with a stronger HeS 6 jet engine. The He 178 jet engine was supplied with air through a front nose Pitot-type intake, then through a curved shaped duct which occupied the lower part of the fuselage, leading directly to the engine. The exhaust gasses would then go through a long pipe all the way to the end of the fuselage. At the developing stage, there were proposals to use side intakes but, probably for simplicity’s sake, the nose-mounted intake was chosen instead. The He 178 fuel tank was placed behind the cockpit.

The He 178 was to be equipped with a retractable landing gear with two larger wheels in the front and a small one at the rear. All three landing gear legs retracted into the aircraft fuselage. For unknown reasons, this was not adopted early on and many test flights were carried out with landing gear in the down position. One possible explanation was that the Heinkel engineers may have left it on purpose. They probably wanted to have the landing gear down in order to be able to land quickly if the engine failed.

First test flights

The first He 178 V1 prototype was completed by June 1939, when it was transported to the Erprobungsstelle Rechlin (test center). Once there, it was presented to Adolf Hitler and Hermann Göring. Interestingly, prior to the flight testing He 178 V1, another Heinkel innovative rocket-powered aircraft, the He 176 was demonstrated. On 23rd June 1939, the He 178 pilot Erich Warsitz performed a few ground test runs. During this presentation, the He 178 was not taken to the sky, mostly due to the poor performance of the HeS 3A jet engine.

Following this presentation, He 178 V1 was transported back to the Heinkel factory in order to prepare it for its first operational test flight. The first He 178 test flight was achieved on 27th August 1939 at the Heinkel Marienehe Airfield near Rostock. At this stage, the pilot, Erich Warsitz, was instructed by the Heinkel engineers not to fly this aircraft at high speeds, mostly due to the fixed undercarriage. In addition, the HeS 3B could only provide enough thrust for only six minutes of effective flight. During this flight, there was a problem with the fuel pump but, despite this, the pilot managed to land with some difficulty but nevertheless successfully.

The flight is best described by the pilot’s own words. ‘…As the aircraft began to roll I was initially rather disappointed at the thrust, for she did not shoot forward as the 176 had done, but moved off slowly. By the 300-meter mark, she was moving very fast. The 176 was much more spectacular, more agile, faster, and more dangerous. The 178, on the other hand, was more like a utility aircraft and resembled a conventional aircraft …In this machine, I felt completely safe and had no worries that my fuel tanks would be dry within a minute. She was wonderfully easy to hold straight, and then she lifted off. Despite several attempts, I could not retract the undercarriage. It was not important, all that mattered was that she flew. The rudder and all flaps worked almost normally, the turbine howled. It was glorious to fly, the morning was windless, the sun low on the horizon. My airspeed indicator registered 600 km/h, and that was the maximum Schwärzler had warned me. Therefore, I throttled back, since I habitually accepted the advice of experienced aeronautical engineers. The tanks were not full and, contrary to custom, I did not want to gain altitude for a parachute jump should things go awry. It was supposed to be a short flight. At 300 to 400 meters altitude I banked cautiously left – rudder effect not quite normal, the machine hung to the left a little, but I held her easily with the control stick, she turned a little more and everything looked good.

After flying a wide circuit my orders were to land at once, this had been hammered into me, but now I felt the urge to go round again. I increased speed and thought, ‘Ach! I will!’ Below I could see the team waving at me. On the second circuit – I had been in the air six minutes – I told myself ‘Finish off!’ and began the landing. The turbine obeyed my movement of the throttle even though a fuel pump had failed, as I knew from my instruments and later during the visual checks. Because the airfield was so small for such flights I was a little worried about the landing because we did not know for certain the safe landing speed: we knew the right approach, gliding and landing speeds in theory, but not in practice, and they did not always coincide. I swept down on the heading for the runway. I was too far forward and did not have the fuel for another circuit. Now I would have to take my chances with the landing, losing altitude by side-slipping. I was flying an unfamiliar, new type of aircraft at high speed near the ground and I was not keen on side-slipping. It was certainly a little risky, but the alternative was overshooting into the River Warnow. Such an ending, soaking wet at four on a Sunday morning, appealed less. The onlookers were horror-struck at the maneuver. They were sure I was going to spread the aircraft over the airfield. But the well-built kite was very forgiving. I restored her to the correct attitude just before touching down, made a wonderful landing, and pulled up just short of the Warnow. The first jet flight in history had succeeded! …’’ Source: L. Warsitz (2008) The First Jet Pilot The Story of German Test Pilot Erich Warsitz.

An interesting fact is that pilot Erich Warsitz managed to be the first man that flew on both a rocket-powered (He 176) and a jet-powered (He 178) aircraft in history.

Heinkel’s attempt to gain the support of the Luftwaffe

During the following months, Hans Joachim tried to improve the HeS 3B jet engine, which would lead to the development of the HeS 6. This jet engine managed to achieve a thrust of 1,300 lb (590 kg), but due to the increase in weight, it did not increase the He 178’s overall flight performance.

As the He 178 was built as a private venture, Heinkel’s next step was to try obtaining state funding for further research from the RLM. For this reason, a flight presentation was held at Marienehe with many RLM high officials, like Generaloberst Ernst and General Erhard Milch. During the He 178 V1’s first attempt to take off, the pilot aborted the flight due to a problem with the fuel pumps. During his return to the starting point, a tire burst out. The pilot, Erich Warsitz, lied to the gathered RLM officials that this was the reason why he aborted the takeoff.
After a brief repair, Erich Warsitz managed to perform several high-speed circuits flights. During the presentation flight, Erich Warsitz estimated that he had reached a speed of 700 km/h (435 mph), which was incorrect, as later turned out… Interestingly, even at this stage, the He 178 was still not provided with the retractable landing gear. The RLM officials were not really impressed with the He 178’s performance, and for now, no official response came from them.

This was for a few reasons. The Luftwaffe had achieved great success during the war with Poland, which proved that the piston-powered engines were sufficient for the job. In addition, Hans Mauch, who was in charge of the RLM’s Technical Department, as opposed to the development of jet engines. He was against the development of jet engines by any ordinary aircraft manufacturer. Another problem was the He 178’s overall performance. During the test flights, the maximum speed achieved was only 595 km/h (370 mph). Hans Joachim calculated that the maximum possible speed with the HeS 6 was 700 km/h (435 mph). The speed was probably affected by the landing gear, which was still deployed and not retracted.

While the RLM did not show any interest in the He 178, Heinkel would continue experimenting with it. While the He 178 did perform many more flight tests, these were unfortunately not well documented. What is known is that, in 1941, the He 178 (with fully operational landing gear) managed to achieve a maximum speed of 700 km/h (435 mph) with the HeS 6 jet engine.

The He 178’s final fate

By this time, Heinkel was more interested in the development of the more advanced He 280. In addition, the use of the HeS 3B jet engine was completely rejected, being seen as underpowered. The interest in the development of the He 178 was lost and it was abandoned. The second prototype, which was similar in appearance, but somewhat larger in dimensions, was never fitted with an operational jet engine. It was possibly tested as a glider. There was also a third mockup prototype built that had a longer canopy.

The He 178 V1 was eventually given to the Berlin Aviation Museum to be put on display. There, it was lost in 1943 during an Allied bombing raid. The fate of the second prototype is unknown but it was probably scrapped during the war. While no He 178 prototypes survived the war, today we can see a full-size replica at the Rostock-Laage Airport in Germany.

Conclusion

Today, it is often mentioned that the He 178 was Germany’s lost chance to get an edge in jet-powered aircraft development. What many probably do not know is that the He 178 was not designed to be put into production, but to serve as a test aircraft for the new technology. We also must take into consideration that the jet engine technology was new and needed many years of research to be properly used. While Germany would, later on, operate a number of jet aircraft, they were plagued with many mechanical problems that could never be solved in time. Regardless, the He 178 was an important step in the future of aviation development, being the first aircraft solely powered by a jet engine

Heinkel He 178 (HeS 6 jet engine) Specifications
Wingspan	23 ft 7 in / 7.2 m
Length	24 ft 6 in / 7.5 m
Wing Area	98 ft² / 9.1 m²
Launch Weight	4.405 lbs / 2.000 kg
Engine	One HeS 6 jet engine with 590 kg (1,300 lb) of thrust
Maximum speed	435 mph / 700 km/h
Cruising speed (when towed)	360 mph / 580 km/h
Crew	Pilot
Armament	None

Gallery

Illustration’s by Ed Jackson

He-178 V1

He 178 V2

Sources

• C.Chant (2007), Pocket Guide Aircraft Of The WWII, Grange Books
• D. Nešić (2008), Naoružanje Drugog Svetskog Rata Nemačka Beograds
• Jean-Denis G.G. Lepage (2009), Aircraft Of The Luftwaffe 1935-1945, McFarland & Company Inc
• M. Griehl (2012) X-Planes German Luftwaffe Prototypes 1930-1945, Frontline Book
• T. Buttler (2019) X-Planes 11 Jet Prototypes of World War II, Osprey Publishing
• L. Warsitz (2008) The First Jet Pilot The Story of German Test Pilot Erich Warsitz Pen and Sword Aviation