Rubik R-25 Mokány

Design and development

In 1957 a team led by Ernő Rubik designed an all-metal glider, the R-23 Gébics, with a pod and boom fuselage, V-tail, fuselage mounted fan airbrakes and corrugated wing skinning. These features were carried forward into a series of gliders that included the R-25 Mokány. This was designed to compete as a Standard Class glider, with a span increased to 15 m (49 ft 5½ in), and introduced a laminar flow NACA 64 series wing profile.

Its straight tapered, high cantilever wing has forward sweep on the trailing edge alone. It is built around a single spar with a D-shaped torsion box formed by the corrugated leading section, the ridges running chordwise. The wing is fabric covered aft of the spar, apart from an outer, metal skinned area carrying Frise ailerons. The all moving V-tail, with 90° separation and fitted with anti-balance tabs, has similar construction and plan as the wings.

The metal skinned fuselage of the Mokány has a circular cross section from the tail forwards to a point a little behind the wing trailing edge where it develops into a deep ellipse, though maintaining the horizontal upper line forward to the leading edge. Beyond this, the cockpit is covered by a single piece blown canopy; the nose is sharply pointed. There is a fixed, partially enclosed and rubber sprung monowheel undercarriage, fitted with a brake and assisted by a small tail skid. Instead of the more usual wing mounted airbrakes, the Mokány has fuselage mounted brakes which open through 90° in fan fashion, with one on either side below the wings at about 25% chord.

The Mokány is fully aerobatic and equipped for cloud flying.

Aircraft on display

The sole Mokány, HA-4300, is on display in the Transport Museum of Budapest.

Specifications (R-25 Mokány)

|prime units?=met General characteristics

|max takeoff weight kg=310 |max takeoff weight note= Performance

|never exceed speed kmh=220 |never exceed speed mph= |never exceed speed kts= |never exceed speed note=still air

• Rough air speed max: 165 km/h
• Aerotow speed: 135 km/h
• Winch launch speed: 115 km/h |minimum control speed kmh= |minimum control speed mph= |minimum control speed kts= |minimum control speed note= |wing loading kg/m2=25.36

Notes

References

References

1. Simons, Martin. (2006). "Sailplanes 1945-1965". EQIP Werbung & Verlag GmbH.
2. Taylor, John W R. (1962). "Jane's All the World's Aircraft 1962-63". Sampson Low, Marston & Co. Ltd.
3. Ogden, Bob. (2009). "Aviation Museums and Collections of Mainland Europe". Air Britain (Historians) Ltd.
4. Shenstone, B.S.. (1963). "The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II". Organisation Scientifique et Technique Internationale du Vol a Voile (OSTIV) and Schweizer Aero-Revue.