The German Aerospace Center (Deutsches Zentrum fuer Luft- und Raumfahrt; DLR) plans to build a realistic replica of the world's first series-produced aircraft and study it scientifically. The project intends to honour the work of aviation pioneer Otto Lilienthal who, 125 years ago, became the first person to pilot an aircraft. In addition, the researchers hope to acquire insight into the cause of Lilienthal's fatal crash.

First human to fly

Lilienthal is considered 'the first human being to fly'. The flights he conducted in 1891 with his self-built glider are considered to be a pioneering achievement in aviation. Balloons that had previously taken people up into the air are not considered aircraft, as they are lighter than air.

Lilienthal's endeavours formed the basis for the first motorised flight by the Wright brothers in the United States and for the work conducted later on by aviation pioneers such as Hugo Junkers and others. This was enabled by Lilienthal's scientific publications and by his - at times - sensational photographs, which received considerable attention both in Germany and abroad.

Investigation in a wind tunnel

"This project, which will involve constructing a historically accurate replica of the world's first series-produced aircraft as it was built by Lilienthal and using it for wind tunnel testing, was initiated not only in order to conduct scientific research into the early days of aeronautics, but also to commemorate and honour one of the world's most renowned aviation pioneers," says Rolf Henke, the DLR Executive Board Member responsible for aeronautics research. "We are the leading aeronautics research organisation in Germany, so this project takes us back to our origins. Our work is based on Lilienthal's scientific legacy."

Paradigm for contemporary aeronautics research

The DLR Institute of Aerodynamics and Flow Technology in Goettingen will conduct the scientific analyses. Andreas Dillmann, Head of the Institute, sees Lilienthal as the father of all modern aeronautical research: "Lilienthal was the first aerodynamic researcher to proceed according to scientific principles. Until then, there had only been hobbyists."

Search for the cause of the crash

The analyses are intended to demonstrate that Lilienthal built an aircraft that was stable about all three axes. Moreover, the wing profile will be closely examined to determine how similar it is to its modern counterparts. Finally, it is hoped that the analyses will provide information about the cause of Lilienthal's fatal crash on 9 August 1869.

Of all the designs that Lilienthal left behind, the 'normalsegelapparat', or conventional glider, is the one that will be reconstructed. This was the world's first series-produced aircraft, of which nine were sold worldwide. It was in this type of aircraft that Lilienthal suffered a fatal accident.

The replica will be built by the Otto Lilienthal Museum in Anklam, using Lilienthal's original design drawings. Lilienthal gliders have frequently been replicated, but this is the first time that a historically accurate replica will be constructed. A series of preliminary analyses and research work will be conducted for this purpose. For example, rigorous testing will be carried out on the fabric covering of preserved, original Lilienthal gliders to determine its properties. Once the replica is complete, it will be tested in one of Europe's largest wind tunnels, located at the German-Dutch Wind Tunnels (DNW) facilities in Marknesse in the Netherlands. "Our aim is to comprehensively understand its flight mechanics and aerodynamic performance," says Dillmann. "How far could he fly, depending on the take-off elevation? In which areas was he able to maintain stable and safe flight?"