M.Simons The World's Vintage Sailplanes 1908-45

THE HORTEN FLYING WINGS

  Inspired by the work of Alexander Lippisch with his tailless sailplanes and powered aircraft, Walter and Reimar Horten began to build their first all-wing glider in 1933. They were still schoolboys but had previously built several experimental models. They took over their parents’ living room at home to build their ‘man-carrying model'. It was of very simple, delta planform like Lippisch’s Delta 1, but with a span of only 12.4 metres. A symmetrical aerofoil was used because of its stationary centre of pressure. The pilot sat in a central nacelle. Control was provided by elevators hinged on the trailing edge of the centre section, with ailerons of orthodox type on the outboard wing panels. There was no rudder; the only vertical ‘keel’ surface was provided by the nacelle. After some trial hops on the local aerodrome, the Horten 1 was taken to the Wasserkuppe for the 1934 competitions.
  The little flying wing flew for some hours in total, but directional control was lacking and it was damaged early in the contest. The boys destroyed it before leaving the mountain, and went back to work on the Horten 2.
  This had a span of 16.5 metres. The angle of sweepback was increased. Instead of the symmetrical aerofoil of the Horten 1, a profile with a reflexed camber was used, and the same applied to all subsequent Horten flying wings. Directional control still remained a problem. The Hortens solved this by installing wingtip spoilers or drag rudders. As the aileron on one side moved up, banking the glider, the drag rudder on the same side, controlled by the pilot’s feet like a normal rudder, could be extended to produce a co-ordinated turn. The ailerons were of the Frise type. This system proved to be very effective and was retained, with refinements, on the later sailplanes. By pushing both rudder pedals together, an airbraking effect was obtained. A central nacelle was provided for the pilot, with a small bubble canopy above the wing. To improve the forward and downward view, six rib bays of the leading edge in front were covered in transparent plastic.
  The H2 was stable in flight. It was claimed to have a best glide ratio of 24 : 1 and a minimum sinking speed of 0.85 metres per second. The prototype was flown in May 1935 and soon afterward was fitted with a 60 hp motor for experiments with motor soaring. During 1936 and 1937, two further examples were built, and at the Wasserkuppe contest in 1937 both brothers entered and created quite a sensation, flying on equal terms with orthodox craft. Both were inexperienced as pilots and did not carry off any awards. Although they were now officers in the growing air force of Nazi Germany, they were given a good deal of freedom to go on with their research. In 1938 they won the Lilienthal Prize and were given financial help to build their next prototype, the Horten 3.
  The Horten 3 was a very big sailplane. The wing area, 37.5 square metres, gave it a low wing loading of less than 10kg/sqm, which contributed to a very good soaring performance. In most ways except size, the '3 was like the ’2, with the same general layout and appearance and the same transparent bay window. A retractable nosewheel was fitted, with a supporting skid at the rear end of the small sub-fin. The wings were 3 metres wide at the root. To transport the Horten 3, a special trailer was needed, the wings alone, standing on their leading edges side by side, towered as high as an average furniture van.
  For the 1938 Rhoen contests two sailplanes were available. One of them, flown by Blech, had a small auxiliary control surface mounted on outriggers just ahead of the cockpit, but the other Horten was truly ‘all wing’. During this contest Blech was one of the pilots killed when cloud flying. His flying wing collided with another sailplane, his neck was broken in the impact and he was thrown out of the Horten 3, his automatic parachute bringing his lifeless body to earth. In the 1939 competitions four Luftwaffe pilots flew Horten 3s. The main disadvantage of these large aircraft was their light wing loading which mitigated against their cross-country gliding performance due to lack of penetration.
  By this time the military possibilities of the flying wing were foreseen. Official support was forthcoming for further work. Various experimental versions of the Horten 3 were built, one with a prone pilot position, a two-seater, and a couple of powered versions with Micron and later, Volkswagen motors. Including the two prototypes, 16 Horten 3s were flown.
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  Technical data:
   Horten 3, 1938: Span, 20.00 m. Wing area, 37.5 sq m. Aspect ratio. 10.66. Flying weight, 360 kg. Wing loading, 9.6 kg/sq m.