Successful Flight Tests
Researchers replicate Lilienthal glider
He made the dream of flying a reality: Otto Lilienthal is regarded as the most influential aviation pioneer of the 19th century. More than 125 years ago, he completed the first gliding flights with his so-called “Normalsegelapparat” (normal soaring apparatus). With great commitment, Markus Raffel, Professor at the Institute of Turbomachinery and Fluid Dynamics (TFD) at Leibniz University Hannover and Felix Wienke have demonstrated that flights up to 100 metres are perfectly feasible. The study is part of Felix Wienke’s doctoral thesis on the aerodynamics of wings permeable to air, which is supervised by Professor Raffel.
Based on drawings by Otto Lilienthal, the mechanical engineers created and tested a replica of the aircraft. They were supported by other flying enthusiasts, as well as by the Otto Lilienthal Museum in Anklam, whose employees contributed their expertise on materials and joining technologies.
On the occasion of the 125th anniversary of human flight in 2016, employees of the German Aerospace Center in Göttingen previously demonstrated the flight stability of the “Normalsegelapparat”. The recent study included strength tests, tethered flights, flights on the hoisting winch, as well as free flights. With these tests, the flying enthusiasts provided aeronautical evidence, that Lilienthal designed an aircraft that is stable around all three axes and can be directed downhill safely.
The flight tests showed that flights between 50 and 100 metres in low altitudes are possible without risk. After some practise, it was relatively easy to keep the glider on course and land it, says Markus Raffel. However, he advises against turning flights or flights in higher altitudes and tough weather, as the apparatus was not designed for such conditions.
In 1893, Otto Lilienthal received the patent for the “Normalsegelapparat”. The inventor flew downhill hundreds of times and sold the device in Moscow, Dublin, Vienna, and New York. More than 100 photographs show Otto Lilienthal in midair. The pictures triggered profound changes and inspired researchers all over the world to look into the subject of flying.
However, the “Normalsegelapparat” was rarely used after Otto Lilienthal’s fatal aircraft accident in 1896. There are no photographs of subsequent flights. In fact, it was assumed that the apparatus was difficult to control and not stable enough. Lilienthal’s studies formed the basis for the first engine-powered flight of the Wright brothers and works of other aviation pioneers.
Note to editors:
For further information, please contact Professor Markus Raffel, Institute of Turbomachinery and Fluid Dynamics at Leibniz University Hannover (Tel. +49 551 709 2817, Email ).