Alexander Schleicher ASK 21

ASK 21
Schleicher ASK 21
Role	Two Seater-class or Club-class sailplane
National origin	Germany
Manufacturer	Alexander Schleicher GmbH & Co
Designer	Rudolf Kaiser
First flight	December 1979
Introduction	1979
Number built	Over 900

The ASK 21 is a glass-reinforced plastic (GRP) two-seater mid-wing glider aircraft with a T-tail. The ASK 21 is designed primarily for beginner instruction, but is also suitable for cross-country flying and aerobatic instruction.

The ASK 21 was designed by Rudolf Kaiser to replace the popular ASK 13, providing a modern two-seat aircraft bridging the gap between initial training and single-seat performance flying. The ASK 21 is the first full-GRP two-seater produced by Schleicher, flying for the first time in February 1979 (6.2.1979). Production also began in 1979, remaining in production to this day (May 2013), over 900 units completed. In December 2004 the ASK 21 Mi, a self-launching version, made its first flight. In 2003 the operating time was extended to 18,000 hours

The two seats are in a tandem arrangement with dual controls, adjustable rudder pedals and seatbacks. The fuselage consists of a tubular sandwich and thus offers passive safety with low weight. The two-piece, mid-set, cantilever wing is a single-spar glass-fiber construction without flaps, but with upper side Schempp-Hirth-type air brakes. The wingtips curve downward, providing tip skids that allow take-offs without a wing helper (small wheel added with ASK-21 mi). The T-tail possesses a fixed horizontal stabilizer and an elevator with spring trim and automatic connections. The undercarriage consists of two or three fixed wheels. The main wheel lies behind the centre of gravity and has a hydraulically operated disc brake. Checking the tire pressure is hindered by the need for removing the wheel fairing. The tail unit has a rubber skid or a tailwheel.

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