The Hannover H.1 Vampyr (known in Germany as the HaWa Vampyr) was a German glider designed by Georg Madelung for the 1921 Rhön gliding competition, which was held at the Wasserkuppe from 8 August to 25 August 1921. The Vampyr is believed to be the first heavier than air aircraft to use stressed skin. Several historical societies have argued that the aircraft is the precursor of all modern sailplanes. Design and development The Vampyr was designed by Georg Hans Madelung, a lecturer at the aerotechnical institute of Leibniz University Hannover, along with students at his university, working under the supervision of Professor Arthur Proell. The aircraft, built at the Hannoverische Waggonfabrik (HaWa) workshops using wood as the primary material, was simple in appearance, but the Vampyr heralded the structural techniques that were to become commonplace as the sport of gliding progressed:Box framed fuselage covered with plywood as a stressed skin, three piece wings with detachable outer panels, a torsion box leading edge, and an enclosed cockpit (only the pilots head was exposed). The most innovative part of the aircraft was its wing. The majority of gliders at this time were monoplanes, and it was becoming appreciated that better performance in terms of glide ratio would come with higher aspect ratio. Long wings were vulnerable to torsional flexing and so most used two spar designs. The Vampyr's designers used a single spar and stabilized the wing with ply covering forward of the spar around the leading edge. This formed a torsion resisting D-box and was probably the first use of stressed skin on any aircraft apart from airships. Behind the spar the wing was fabric covered. It was built in three parts, a rectangular centre section and two tapered outer panels bearing ailerons. By 1922 these had been replaced by parallel, swept sections with provision for wing warping. The strength of the wing, mounted on top of the fuselage, required only short lift struts between the spar and fuselage. The pilot sat under the wing leading edge in an open cockpit; forward of the wing extra fuselage panels gave the fuselage a hexagonal cross-section. Three balls, one in the nose and two side by side under mid-wing formed the undercarriage. Flying controls were essentially conventional with fin, rudder, all-flying tailplane, and ailerons on the outer panels on the 1921 version. For the 1922 competition outer panels of increased area and wing-warping