The rapid development of modern jet aircraft has opened the world up to affordable and convenient air travel, but its initial learning curve was long and dangerous. While aviation history is rich with pioneering figures such as Otto Lilienthal, the Wright brothers and Charles Lindberg, the transition from front-propeller to rear-engine-powered aircraft occurred around the time of the Second World War – which meant countries such as the UK, US and Germany were all competing to make the first discovery.
As such, engineering progress was often a closely guarded secret, as were some of the life-threatening test flights. This was particularly the case in Germany during the 1930s, when the Third Reich began to take a strong financial and supportive interest in the research of Wernher von Braun, who was experimenting with fitting liquid-fuel rockets to aircraft. He eventually became paired with Dr Ernst Heinkel – one of the great aeronautical designers of the age – and by 1936, they had advanced far enough with their trials at Kummersdorf to begin test flights in Neihardenberg.
It was at this point that Erich Warsitz was recruited from the Reich Aviation Ministry (Reichsluftfahrtministerium – RLM) to boldly pilot the new HE 112 aircraft. Warsitz went on to become the first man to fly an aircraft powered by a liquid-fuel rocket engine (He 176) before going on to steal the accolade of also being the first pilot to fly with a jet engine (He 178). His son Lutz Warsitz recently completed a book on his father's contribution during a monumental period of aviation history. Here he discusses Erich Warsitz's life-threatening test flights with Alex Hawkes and explains the lasting impact such research has left on the aviation industry.
Alex Hawkes: I understand your father spent over two years as a test pilot for the German Air Force before being recruited by Heinkel. How did that experience lead to Erich Warsitz's selection as the first man to fly an aircraft driven by a liquid-fuel rocket engine?
Lutz Warsitz: Between 1934 and 1936, my father flew almost every kind of propeller aircraft tested at the Luftwaffe's test centre in Rechlin. He therefore possessed all known aircraft licences of the time, including licences for flying long distances and overseas.
Perhaps what made him stand out from other candidates, however, was his technical knowledge. My father was also studying automotive and aircraft engineering, and it was important for the pilot to be able to report technical issues back to the research team after every flight test. The RLM team was also careful to check that my father was unmarried – which he was at the time – as the risk involved during the testing period was extremely high.
AH: With that danger in mind, how precarious was the initial testing period of the first aircraft to use an auxiliary rocket motor, which was an He 112 fitted with an auxiliary von Braun rocket motor?
LW: Initial testing of the He 112 took place in a small airfield near Neuhardenberg, which was 70km east of Berlin. Before its first flight, a period of ground testing was done with the He 112, whereby the von Braun engine was remotely ignited. It exploded many times before they allowed my father to do the first engine testing from within the aircraft.
Despite this, my father's first attempt at internally igniting the von Braun engine saw the aircraft explode and he was catapulted a few metres away from its remains. This was the first of many near-death experiences for him.
life-threatening test flights."
In 1937, a second airworthy He 112 arrived at the testing site and it was fitted with a new von Braun engine. This time my father was able to ignite the engine and fly the aircraft about 200m up into the air. Unfortunately, smoke and gas then began entering the cockpit as the engine again caught fire. As the aircraft was not high enough for my father to parachute out, he was forced to crash-land it in a field.
The ground-crew were quick to react and put out the flames, which is when they discovered that the combustion chamber had a small crack and fuel was spilling out and burning. Had the flames melted the rudder, my father would have had no control of the aircraft and been in much keener danger.
AH: So what lessons were taken from the testing period of the He 112 that allowed for the subsequent development of the He 176 and He 178?
LW: The RLM wanted to develop a new generation of fighter aircraft, which is how the creation of the He 176 came about. The project was classified as top secret and its research received substantially greater investment, but the aircraft itself had a much smaller body with a wheel base of just 700mm. As the aircraft was without propellers, it struggled to create wind for the rudder, which meant steering during take-off was a huge challenge. My father had to use the sensitive breaking mechanisms to balance the aircraft, which was liable to spin or flip at any given moment. Though it happened a few times, he managed to eventually fly the machine.
Most importantly though, the He 176 possessed a softer rocket engine – known as the Walter engine, which relied on a chemical reaction that produced hot vapours instead of fire. This engine allowed for the world's first successful manned rocket flight but it did not do enough to impress the RLM, which with the Second World War looming decided to officially stop supporting the project.
Without the RLM knowing, the Heinkel team decided to pursue the development of the He 178. Hans Joachim Pabst von Ohain had meanwhile been developing the He-S3 turbine and it was decided to test this new jet engine. By 1939, a version of the engine was installed in the frame of a He 178 and it was this vehicle that allowed for the first ever flight using a jet engine.
AH: Do you think your father and the Heinkel design team were aware at the time of how revolutionary their work was?
LW: They were so absorbed with their work and committed to the development of the aircraft that they probably didn't pay much attention to that aspect.
But yes. After it was established that the future of their work was with jet engines and not rocket engines, my father said that it would be ten or 15 years until planes would be mainly using jet engines instead of propellers.
AH: And how exactly did all their trials and tribulations ultimately lay the foundations for the modern jet engine?
LW: They of course made important discoveries with both the rocket engine and the jet engine – but overall, to establish that the jet engine is the less dangerous of the two, that it is capable of flying longer distances and consuming less fuel, have been the lasting legacies of my father's work.
That research team also went on to establish a few basic facts that are still applied to aircraft today, such as the need for a nose wheel to enable greater control of the steering during take-off.
Due to the project's secrecy and its connotations with Nazi Germany, my father never received the recognition I think he deserved at the time. Hopefully, the interest generated from my book The First Jet Pilot will help rectify that.
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