Saab J 21
The Saab J 21 was a Swedish single-seat fighter and attack aircraft of unconventional layout: a license-built Daimler-Benz engine behind the pilot drove a pusher propeller between twin tail booms, freeing the nose for cannon and giving the type one of the first ejection seats fitted to a production aircraft. First flown in 1943 and in service from December 1945, it was built in fighter and fighter-bomber versions and was later converted to jet power as the Saab 21R.
Why It Mattered
The Saab 21 was the fighter Sweden produced for itself when the Second World War made importing a modern one nearly impossible. Wartime suppliers would not sell fighters to a neutral country, so the Swedish Air Force expanded on its own and Saab answered with one of the most unconventional fighters of the war. The type was among the first production aircraft in the world to fly with an ejection seat. Its airframe then crossed into the jet age: converted to jet power as the 21R, it became one of only two fighters ever successfully re-engined from piston to jet. It also began Saab's line of home-grown fighters, continued by the Saab 29 Tunnan that replaced it.
Design Notes
The 21 put its engine behind the pilot. A Daimler-Benz DB 605B, license-built in Sweden by Svenska Flygmotor, sat at the rear of a short central nacelle and drove a pusher propeller. Two booms extended back from the wing to carry the tail, the wing itself was low-set, and the aircraft stood on a tricycle landing gear. With no propeller ahead of him, the pilot had a clear view forward, and the nose — freed of the usual engine — could carry a concentrated battery of cannon. The layout had one serious danger: a pilot bailing out could be drawn into the propeller behind him. Saab's answer was an ejection seat, developed by the Swedish firm Bofors and built into the design.
Operational History
The prototype made its maiden flight on 30 July 1943, flown by Saab test pilot Claes Smith. The flight nearly ended the program at the start: Smith used too much flap on takeoff, the aircraft struck a fence and damaged its undercarriage, though he brought it back to a safe landing. Deliveries to the Swedish Air Force began on 1 December 1945. The Svea Wing (F 8) was the first unit to receive the J 21, and the Göta Wing (F 9) followed. Production reached 298 aircraft in all — two fighter series and the J 21A-3 fighter-bomber. Although the type was intended principally for air defence, in service it was used mainly as a light bomber. From 1947, Saab converted airframes to jet power around the British de Havilland Goblin engine; the resulting 21R first flew on 10 March 1947, 64 were built, and they served mainly as fighter-bombers. The piston-engined J 21A began to be retired in 1954, and the type gave way to the de Havilland Vampire and Saab's own 29 Tunnan.
Afterlife
Three J 21A-3s survive on permanent static display. Two are held by the Swedish Air Force Museum: serial 21364, and serial 21286, which was rebuilt to represent the jet-powered A 21R. The third, serial 21311, is at the F 15 Söderhamn Flygmuseum. The type's place in this catalog rests on that double life — Sweden's home-grown wartime fighter, and one of the very few aircraft to serve in both piston and jet forms.