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Страна : Германия

Год : 1935

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

THE RHOENSPERBERS

  With the Rhoensperber, his new design of 1935, Jacobs aimed for a smallish, easily manufactured sailplane for general use, but with a good cross-country performance. The wing was aerodynamically similar to the Bussard, but had a greater span. Some of the increase in span, and hence aspect ratio, was achieved by mounting it at shoulder level on the fuselage instead of high on a pylon. The rigging system was also simplified, the main spars joining inside the fuselage on the centre line but with the main steel pins going in horizontally. All the bending loads were thus carried through the spar. The fuselage was then held to the wing by smaller horizontal pins, one at the drag spar position and the other under the main spar. This last feature necessitated a small underwing 'armpit' fairing, since no access to this pin was possible from inside the fuselage. To retain adequate ground clearance, Jacobs, for the first time, used the 'gull' dihedral form. The tail unit resembled that of the Rhoenbussard but was slightly larger. Two horizontal steel rods, running athwartships, connected the tailplane to the top of the rear fuselage frames.
  The most noticeable feature of the Sperber was that the pilot could see in all directions from his 'teardrop'-shaped canopy, which was a light steel tubing frame covered with separate sheets of Plexiglass. The cockpit was large enough for all pilots and there was space for parachute and instruments. The Sperber was also stressed for aerobatics and could be flown safely up to 200 km/h. The improved fuselage and wing root junction, together with the greater span, gave it a better performance than the Rhoenbussard. Flight tests showed that its best glide ratio was close to 22 : 1. This was an excellent figure for a relatively simple club or privately-owned sailplane that could be bought ‘off the shelf'. The type entered production in 1935 at Flugzeugbau Schweyer and about a hundred were produced altogether, before manufacture was discontinued. The first pilot to show what the new aircraft could do was Ludwig Hofmann in 1935. The world record stood at 375 km. It had been set by the great Heini Dittmar almost exactly a year previously in the most refined sailplane of the day, the Fafnir 2. Hofmann followed a similar route but went further into Czechoslovakia, landing at Olesnice after 474 km. It was the first soaring flight over 400 km. Hofmann’s exploit would have been remembered longer if it had not been exceeded within the week. On 29th July four gliders reached Brunn, further still into Czechoslovakia, and the record then stood at 504.2 km. One of the four was a Rhoensperber piloted by Hans Heinemann. There were nine Rhoensperbers competing. The Sperber was not free from teething troubles however. During this Wasserkuppe meeting most of the pilots hurriedly modified their Rhoensperbers by adding spoilers on the upper surfaces of the wings, and on the sixth day all were grounded when a technical analysis indicated an unexpected weakness in the metal root fittings. Flying ceased abruptly while modifications were done, but all soon flew again.
  The next year the Rhoensperber was the most popular single type at the Wasserkuppe. Several were exported, one to England where it quickly established a good reputation, especially when flown by Kit Nicholson.
  Ernst Udet, a famous sporting pilot who was later to become Goering’s scapegoat for the failure of the Luftwaffe, flew his own personal Rhoensperber at the Berlin Olympic Games display in 1936; like the other sailplanes at this display, the aircraft carried the Olympic linked rings painted on its nose. Udet, as the leader of the German team with Dittmar, Hofmann and Riedel, went to the 1935 Jungfraujoch contest and flew his sailplane there. Ideas were advancing rapidly and the Sperber was already beginning to look out of date. In time for the 1936 Rhoen, Hans Jacobs built for Hofmann an enlarged Rhoensperber, the Sperber Senior. It had greater span and a different wing planform, a larger cockpit and new aerofoils, giving it a better glide ratio at higher speeds. The Sperber Senior was sent to New York by the German Aero Club in June 1937, for Peter Riedel to fly in the Elmira contest. As a training flight, before going to Elmira, Riedel soared for a remarkable seven hours after a launch from Roosevelt Field on Long Island. He flew over downtown Manhattan, crossed to New Jersey on the other side of the Hudson, and back to Roosevelt Field to land. Proceeding to the contest in the following month, Riedel won the most points but as a visitor he was ineligible for the US Championships. After the contest, although attempts were made by American pilots Io buy the Sperber Senior, it was shipped back to Germany and no evidence has been found to show that it ever flew again.
  Also flying in the US at this time was a standard Rhoensperber belonging to Emil Lehecka. It carried the name, Guenther Groenhoff.
  The Rhoensperber was too large for some pilots. Hanna Reitsch needed the seat padded with cushions to bring her head up to the cockpit coaming. For her, Jacobs designed the Sperber Junior. The aerofoil was again the Goettingen 535, but the span was stretched and the planform was similar to Hofmann’s aircraft. The fuselage was tailored to fit Hanna's small figure, the ‘teardrop' cockpit canopy being dispensed with and instead a wooden hood with partly glazed portholes was substituted, and a shape rather like that on the Fafnir 1, was used. Hanna’s aircraft was painted with a spectacular blue and cream ‘sunburst' color scheme. Today several Rhoensperbers survive in varying conditions. Two are complete in storage in Germany, but are not airworthy. Another, Nicholson’s old aircraft, was rebuilt during the late 'seventies at Tangmere, although fitted with a Rhoenbussard tailplane and elevator.
  The performance figures, weights, etc, quoted below come from the DFS flight tests reported by Spilger in 1937.

  Technical data:
   Rhoensperber: Span. 15.20 m. Wing area. 15.1 sq m. Aspect ratio: 15.3. Empty weight. 182.5 kg. Flying weight. 287.5 kg. Wing loading. 19.0 kg/sq m. Aerofoil, Goettingen 535 at root and over centre section, tapering to thin symmetrical Goettingen 409 at the tip. Best glide ratio, 1:21.6 at 63 km/h. Minimum sinking speed. 0.73 m/sec at 50.5 km/h. Sink at 100 km/h, 1.74 m/sec.
   Sperber Senior: Span, 16.00 m. Wing area, 16.2 sq m. Aspect ratio, 15.8. Empty weight, 186 kg. Flying weight, 291 kg. Wing loading, 18.0 kg/sq m. Aerofoil, Goettingen 757 at root and centre section, tapering to Goettingen 767 at tip. Best glide ratio, 1:22.7 at 67 km/h. Minimum sinking speed 0.74 m/sec at 56.5 km/h. Sink at 100 km/h, 1.63 m/sec.
   Sperber Junior: Span. 15.60 m. Wing area, 15.5 sq m. Aspect ratio. 15.7. Empty weight, 175 kg. Flying weight, 280 kg. Wing loading, 18.1 kg/sq m. Aerofoils, as for Rhoensperber. Best glide ratio, 1:24.3 at 68 km/h. Minimum sinking speed 0.65 m/sec at 48.5 km/h. Sink at 100 km/h, 1.5 m/sec.

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Описание:

  • M.Simons The World's Vintage Sailplanes 1908-45
  • M.Hardy. Gliders & Sailplanes of the world
  • Фотографии