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    Saab J21 Fighter / Attack Aircraft

    The Saab J21 appeared at the end of World War 2 as a prop-driven fighter only to later become a fully jet-powered platform in the J21R.

     Updated: 7/17/2016; Authored By Staff Writer; Content ¬©www.MilitaryFactory.com

    Sweden elected to remain neutral during the fighting of World War 2 (1939-1945) but this did not mean that it stood blind to the situation around it. The Soviet Union had invaded neighboring Finland and the Germans took Norway leaving Sweden as the lone Scandinavian power (Denmark too had fallen to the Germans on the European mainland). The Swedish Air Force drew up a request for a new modern fighter in 1941 intended to replace the now-obsolete American- and Italian-originated types that were still in frontline use for the service.

    Design work on the aircraft followed and was led by Frid Wanstrom of Svenska Aeroplan AB. The team began with a single-seat, single-engine concept and this evolved to include a twin-boom layout. To provide for better forward views out-of-the-cockpit, the engine was set aft of the pilot in a "pusher" configuration. Not only was situational awareness a strong quality but the nose assembly was now free to be fitted with a collection of guns (as was the case with the American Lockheed P38 Lightning fighter). The pilot sat under a heavily-framed canopy and the raised fuselage spine restricted views to the rear. A straight monoplane wing planform was used that featured clipped tips and slight sweepback along the leading and trailing edges of the outboard planes. The empennage had a twin-finned configuration with a central plane joining the two fuselage booms. A modern tricycle undercarriage, fully retractable, rounded out the design elements which proved the aircraft rather innovative for its time.

    The engine of choice became the German Daimler-Benz DB 605B 12-cylinder inverted Vee engine and this drove a three-bladed propeller unit at the rear of the cockpit nacelle, forcing air over and under the tail plane. Intakes were built into the wing leading edges (at the wing roots) to help aspirate the engine at rear. These powerplants would be built locally, under license, through SFA (Volvo Aero).

    In terms of armament, the aircraft was given 1 x 20mm cannon along with 2 x 13.2mm machine guns and these were all fitted in the nose assembly. An additional 2 x 13.2mm machine guns were seen in the wings - one per wing.

    A prototype made it to the air for the first time on July 30th, 1943 and two more followed for the test phase to come. The aircraft was given the designation of "J21" and Saab was charged with its serial production. The first operational-quality form became "J21A-1" and these served with the Flygvapnet through deliveries beginning in July of 1945. However, the war in Europe had ended in May of 1945 and the World War, in whole, would be over with the Japanese surrender of August. The Swedish Air Force took on a stock of 54 J21A-1 fighters nonetheless.

    At the time of its adoption, the J21 was the only frontline fighter of pusher configuration to be adopted for service in World War 2. It was also the second fighter type anywhere in the world to feature an ejection seat as standard - this design element essentially forced upon engineers by the fact that the pilot would be vacating his doomed aircraft ahead of the spinning propeller blades - he simply could not roll off of the wing as usual and hope to clear the blades naturally. The German He 219 "Eagle-Owl" night-fighter became the first operational-level aircraft fitted with an ejection seat and the feature became standard on all fighters since.

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    Saab J21RB Technical Specifications

    Service Year: 1945
    Type: Fighter / Attack Aircraft
    National Origin: Sweden
    Manufacturer(s): Saab - Sweden
    Production Total: 304

    Structural (Crew Space, Dimensions and Weights)

    Operating Crew: 1
    Length: 34.28 feet (10.45 meters)
    Width: 38.06 feet (11.60 meters)
    Height: 9.68 feet (2.95 meters)

    Weight (Empty): 7,055 lb (3,200 kg)
    Weight (MTOW): 11,001 lb (4,990 kg)

    Installed Power and Standard Day Performance

    Engine(s): 1 x de Havilland Goblin II turbojet engine developing 3,307 lb of thrust (Daimler-Benz propeller pusher engine used in J21A).

    Maximum Speed: 497 mph (800 kph; 432 knots)
    Maximum Range: 447 miles (720 km)
    Service Ceiling: 39,370 feet (12,000 meters; 7.46 miles)
    Rate-of-Climb: 4,600 feet-per-minute (1,402 m/min)

    Armament / Mission Payload

    1 x 20mm Bofors (Hispano) cannon in nose
    2 x 13.2mm Bofors (Colt) machine guns in nose
    2 x 13.2mm Bofors (Colt) machine guns in wings (one per wing).

    OPTIONAL (strike role):
    8 x 13.2mm machine guns in ventral gun pack
    8 x 14.5cm Air-to-Surface Unguided Rockets
    4 x Conventional Bombs

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    Model Variants (Including Prototypes)

    J21 - Base Series Deisgnation

    J21A-1 - Initial Production Model; 54 examples produced; fitted with Daimler-Benz pusher engine; ejection seat; 54 examples completed.

    J21A-2 - Follow-Up Production Model; fitted with Swedish-made armament (20mm cannon); internal changes; 124 examples produced.

    J21A-3 - Dedicated Attack Variant; Initial Production Model of that type series; based on the J21A-2; fitted with bombsight for strike operations; provision for undermounting of rockets and bombs; RATO optional; 66 examples completed.

    J21B - Proposed Variant; fitted with 3 x 20mm cannons; radar installation in starboard boom; Daimler-Benz DB605E series engines OR Rolls-Royce Griffon series engines; never produced.

    J21R - Jet-Powered Version Base Designation

    J21RA - Fitted with de Havilland Goblin II series turbojet engine of 3,000lb thrust; 30 examples.

    J21RB - Fitted with de Havilland Goblin III series turbojet engine at 3,305lb thrust; appearing in 1949 onwards; 30 examples.