Raab Krähe

Krähe
Raab Krähe IV Powered Glider D-KORL at the Deutsches Museum Flugwerft Oberschleißheim
Role Motor glider
National origin West Germany
Designer Fritz Raab
Introduction circa 1958
Status No longer in production
Number built 30

The Raab Krähe (English: crow) is a West German high-wing, single-seat, pusher configuration motor glider that was designed by Fritz Raab for amateur construction around 1958.[1]

Design and development

Raab designed the Krähe specifically for homebuilders.[1]

The Krähe is constructed from wood, with the fuselage made from a wooden structure covered in doped aircraft fabric. The 12.0 m (39.4 ft) span wings are built with a wooden structure and covered in plywood and fabric. The wings feature spoilers and a custom Raab-designed airfoil. The tailplane is braced with four cables to the wing trailing edge. The landing gear is a fixed monowheel.[1]

The motor installation is unconventional for a motorglider in that the engine is mounted in the rear of the cabin area, with the propeller in between the top and bottom tail boom tubes. Motors used are usually of an output of about 30 hp (22 kW).[1]

About 30 examples were reported completed by 1974.[1]

Operational history

One Krähe built in Austria by Tasso Proppe and imported to the United States was powered by a 27 hp (20 kW) Steyr twin-cylinder, four-stroke engine that produced a cruise speed of 75 mph (121 km/h) on a fuel burn of 1.2 U.S. gallons (4.5 L; 1.00 imp gal) per hour. The aircraft is no longer on the US Federal Aviation Administration registry.[1][2]

Variants

Krähe
Initial model with monowheel landing gear and propeller in between top and bottom tail boom tubes.[1]
Austria Krähe
Later model with tricycle landing gear and propeller rotating around the upper tail boom tube.[1]

Specifications (Krähe)

Data from Soaring[1]

General characteristics

  • Crew: one
  • Wingspan: 12 m (39 ft 4 in)
  • Wing area: 14.3 m2 (154 sq ft)
  • Aspect ratio: 10:1
  • Airfoil: Raab
  • Empty weight: 238 kg (525 lb)
  • Gross weight: 333 kg (735 lb)
  • Fuel capacity: 8 U.S. gallons (30 L; 6.7 imp gal)
  • Powerplant: 1 × Steyr , 20 kW (27 hp)
  • Propellers: 2-bladed wooden fixed pitch

Performance

  • Cruise speed: 121 km/h (75 mph, 65 kn)
  • Endurance: 10 hours loiter
  • Maximum glide ratio: 18-20:1 at 77 km/h (48 mph)
  • Rate of sink: 1.2 m/s (240 ft/min) at 68 km/h (42 mph)
  • Wing loading: 23.3 kg/m2 (4.77 lb/sq ft)

See also

Related development

References

  1. ^ a b c d e f g h i Rogers, Bennett: 1974 Sailplane Directory, Soaring Magazine, page 87. Soaring Society of America, August 1974. USPS 499-920
  2. ^ Federal Aviation Administration (August 2011). "Make / Model Inquiry Results N11224". Retrieved 5 August 2011.