J-29 Tunnan

The Saab 29 Tunnan ("The Barrel") was a single-seat jet fighter designed and produced by Saab of Sweden. It was Sweden's second turbojet combat aircraft after the Saab 21R and the first Western European fighter with a swept wing to be produced after the Second World War. Deliveries to the Swedish Air Force began in May 1951, and the type served in fighter, fighter-bomber and reconnaissance roles into the 1970s. It is known for its rotund fuselage, from which its nickname derives, and for being the first Swedish jet to see combat.

Development

Work began in late 1945 under the project designation "JxR", with requirements drawn up in October 1945. The Saab team under Lars Brising submitted two proposals: the R 101 "cigarren", resembling the Lockheed P-80, and the barrel-shaped R 1001, which was selected as faster and more agile. The initially straight wing was given 25 degrees of sweep after Saab project manager Frid Wänström obtained German swept-wing data in 1945, including drawings of the Messerschmitt P.1101, P.1110, P.1111 and P.1112; Messerschmitt aerodynamicist Hermann Behrbohm joined the J 29 team. A Saab Safir was rebuilt as the Saab 201 to test a full-scale swept wing. The de Havilland Goblin was replaced by the more powerful de Havilland Ghost in December 1945, its circular intake and diameter suiting the planned fuselage. The Swedish Air Force ordered three prototypes as the J 29 in autumn 1946; four were ultimately built. The first flight took place on 1 September 1948 with S/L 'Bob' Moore at the controls. Between 1950 and 1956, 661 aircraft were completed, the largest production run of any Saab aircraft.

Design

The Tunnan has a nose air intake with a straight-through duct, a bubble canopy above the duct, and a thin mid-mounted two-spar swept wing attached to the fuselage by four bolts. The undercarriage retracts into the fuselage to keep the wing thin and was designed for rough airstrips. Automatically locking leading-edge slots interconnected with the flaps provided lateral stability at low speed, and a dog-tooth leading edge was later added to raise the critical Mach number. Structure used a Swedish equivalent of 75S aluminium alloy produced by Svenska Metallverken, with heavy frames and stressed skin. Power came from a 22.4 kN de Havilland Ghost; the J 29F used the afterburning Svenska Flygmotor RM2B, the first successful afterburner fitted to a British engine. A Saab ejection seat of 1943 design and explosive canopy jettison were fitted.

Armament

Fixed armament was four 20 mm akan m/47C autocannon with 180 rounds per gun. Eight inner hardpoints carried rocket pylons and two outer hardpoints took drop tanks or 200 kg brandb m/51 incendiary bombs; 600 kg drop tanks could be filled with napalm. Rocket types included the 75 mm srak m/55 air-to-air rocket, the 80 mm prak m/46C, the 145 mm psrak m/49 shaped-charge, the 150 mm srak m/51 and the 180 mm hprak m/49. From 1963 all frontline J 29Fs carried the Rb 24 (AIM-9B Sidewinder).

Operational History

A J 29 set a world speed record over a 500 km closed circuit in 1954 at 977 km/h, and two S 29C set a 1,000 km closed-circuit record of 900.6 km/h in 1955. The early accident rate was high, partly because no two-seat Tunnan trainer existed; 99 pilots were killed in Swedish practice flights. Five J 29Bs deployed to the Republic of the Congo as F 22 Wing in September 1961 for the UN ONUC mission, reinforced in 1962 by four more J 29Bs and two S 29C. Missions were mainly cannon and rocket attacks on ground targets; no aircraft were lost in action, the sole loss being an aborted takeoff crash. Austria bought 15 J 29F in 1961 and a further 15 in 1962, the second batch modified with a nose camera pod replacing two cannon and never armed with missiles; they served until 1972. Swedish fighter versions were withdrawn in May 1967, with survivors used for target towing and countermeasures training; the last military flight was in August 1976.

Variants

• J 29A: First production fighter variant, powered by the de Havilland Ghost.
• J 29B: Improved fighter with increased internal fuel, used in the Congo.
• S 29C: Dedicated photo-reconnaissance variant with cameras in the nose.
• J 29E: Fighter introducing the dog-tooth leading edge.
• J 29F: Final variant, combining the dog-tooth wing with an afterburning RM2B and Rb 24 missiles.