Early swept-wing tailless aircraft concepts – A historical perspective.

The 1920’s and 1930’s in Germany were a time of great innovation in aircraft and propulsion design. This is due to a few factors, post World War-I politics, German government support and the coaching by old aeronautical geniuses.

During most of the 1920’s Germany was prohibited from developing or manufacturing military aircraft. This led the aviation enthusiasts to sailplane and gliding competitions. The sailplane competitions encouraged quick and inexpensive development of new ideas. These competitions trained an entire generation of aeronautical engineers. The aerodynamic edge was constantly extended along with the development of lightweight building techniques. The competitions culminated on a 950-meter peak in the Bavarian Alps called Wasserkuppe. This was where the Olympics of gliding were held every year. This area was perfect for gliding, gentle grass-covered slopes, which fell away into wide-open valleys. By 1937 there was a large complex of buildings catering to the gliding community.

 

The rise of the NSDAP party and Germany’s aspirations of regaining some of its power and prestige led the German government to wholeheartedly support the education of aeronautics in schools and the official support of the sailplane competitions. Sponsorships and grants for innovative ideas became plentiful in the 1930s. (Ransom, 2001).

On Pentecost takes place on the Wasserkuppe a Reich competition of glider models.

Aeronautical greats such as Prandtl, Ahlborn and Lilienthal trained or inspired this new generation of engineers competing at Wasserkuppe. Prandtl derived the basis for much of the fluid dynamic theory used today. Prandtl was very interested in the glider competitions and became friends with a young engineer named Alexander Lippisch who would develop the Me-163 and much of the theory of Delta wings. Prandtl along with Lippisch went on to coach the teenage Horten brothers who would go on to almost 60 years of tailless aircraft research. Professor Ahlborn, through his study of a gliding seed called Zanonia (Macrocarpa) in the 1890’s inspired many tailless aircraft designs. Ahlborn documented the hydrodynamics of this tailless flying seed and ran the German Hydrodynamic Institute into the 1920’s. The Zanonia seed achieved stable flight by using a combination of swept wings with up to 10 degrees of washout at the tips. The washout at the tip provided a negative pitching moment, which countered the positive pitching moment of the center section. This information became the foundation for tailless aircraft theory developed by the Hortens and Lippisch as well as the British engineer John Dunne. Lilienthal who is Germany’s equivalent to the Wright brothers conducted a number of manned glider flights in the 1890’s also provided inspiration.

The Zanonia seed, which inspired many to research tailless flight. The seed average 10-15 cm in span and glide long distances from their parent trees in Java. (Wahl,1987)

 

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