Raab Krähe

Design and development

Raab designed the Krähe specifically for homebuilders.

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.

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).

About 30 examples were reported completed by 1974.

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.

Variants

Krähe

Initial model with monowheel landing gear and propeller in between top and bottom tail boom tubes.

Austria Krähe

Later model with tricycle landing gear and propeller rotating around the upper tail boom tube.

Specifications (Krähe)

Data from Soaring

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; 65 kn (75 mph)

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)