Saab 21

SAAB 21
Saab J 21A-3
Role	Fighter and attack aircraft
Manufacturer	SAAB
Designer	Frid Wänström
First flight	30 July 1943
Introduction	1 December 1945
Retired	23 July 1954
Status	retired
Primary user	Swedish Air Force
Produced	1945–49
Number built	298
Developed into	Saab 21R

The SAAB 21 was a Swedish fighter/attack aircraft from SAAB that first took to the air in 1943. It was designed as a twin boom pusher configuration, where the propeller was mounted in the rear of the fuselage, pushing the aircraft forward.

Sweden wished to ensure its continued neutrality through a policy of armed strength during World War II but was effectively denied access to foreign weapons. The original design studies began in 1939, based around the use of a Bristol Taurus engine within the center fuselage, behind the pilot, driving a pusher propeller. The project remained dormant until 1941. In response to the need for air defence, and faced with the prospect of imported designs being unavailable due to the war, Sweden undertook an indigenous rearmament programme including an advanced fighter. The low-wing monoplane Saab 21 fighter was ultimately designed around a license-produced version of the Daimler-Benz DB 605B engine, featured innovations such as tricycle landing gear, heavy forward-firing armament, ejector seat, and a twin-boom pusher layout that later allowed the type to be modified with a turbojet engine.

The advantages of a pusher design are that the view forward is unobstructed and armament can be concentrated in the nose, while a major drawback is difficulty in escaping from the aircraft in an emergency, as the pilot could get drawn into the propeller blades. Saab deliberated between systems that would eject the pilot, or jettison the propeller or the engine, via a system of explosive bolts, and eventually installed an early ejector seat developed by Bofors for the purpose and tested in 1943.

In 1947, the aircraft was extensively redesigned with over 50% airframe, tailplane and wing changes and fitted with a de Havilland Goblin turbojet, acquiring the new designation Saab J 21R.

The first of three J 21 prototypes flew on 30 July 1943 flown by SAAB test pilot Claes Smith. During the takeoff, the wrong flap setting resulted in the prototype running into a fence at the end of the runway, damaging one of the landing gears. The subsequent test flight ended with a successful landing on the undamaged undercarriage units.

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Wikipedia