M.Simons The World's Vintage Sailplanes 1908-45
Lajos (Louis) Rotter, engineer and pilot, was one of the driving forces behind the early gliding movement in Hungary. The Karakan was his first high performance sailplane design. Two were built in 1933/34. Rotter fitted large
‘V’ struts to the wing to maintain strength without increasing the weight too much. The centre panels had a well-cambered but relatively thin aerofoil, which tapered over the outer panels to the usual symmetrical profile at the tip, with washout to prevent tip stalling. The ailerons conformed to the taper, reducing in chord outward. The single mainspar, with plywood covered, torsion-resisting 'D' nose, was entirely orthodox with a light rear spar to stiffen the rear sections of the ribs and additional internal diagonal bracing to take the end loads from the rear ‘V’-strut member.
The fuselage cross-section was lens or almond-shaped, with a keel member at the top and bottom. This was to reduce aerodynamic drag at various airspeeds. In theory, the lenticular cross section would create less resistance to air flowing over it at an angle when the sailplane was flying either nose-up or nose-down, when compared to an elliptical form or the more usual ‘pointed pear’ shape. The plywood covering was easily applied since little bending was required and stout keel longerons provided good glueing surfaces at the top and bottom. The seat was comfortable and a semi-enclosed transparent canopy with several large, unglazed openings was fitted. The wings joined, behind and above the cockpit on the centre line, with three bolts, the leading edge spar, mainspar and drag spar all being aligned on the same axis.
The Karakans were very successful. Rotter established many national records and became Hungary’s first Silver ‘C’ pilot, actually number 19 on the international list. The Karakans continued flying for some years. The second one was destroyed in an accidental hangar fire at Farkashegy, the gliding site near Budapest, in 1942. The prototype was displayed in the Hungarian National Transport Museum in the capital, but was destroyed there when the Museum was devastated during the fighting in 1944/45.
Karakan: Span, 20.00 m. Wing area, 21.05 sq m. Aspect ratio. 19.00. Empty weight, 230 kg. Flying weight, 330 kg. Wing loading, 15.7 kg/sq m. Best glide ratio claimed, 1:25. Minimum sinking speed, 0.8 m/sec.