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SAAB J-21

saab21


On 1 April 1939, the Air Force Materiel Administration invited AB Förenade Flygverkstäder to tender for a new fighter aircraft to be powered by the new Bristol Taurus en-gine, a sleeve-valve unit delivering 1,200 hp. The timetable was incredibly tight. Saab proposed a radical configuration (designated the Ll3) in which the engine was mounted behind the cockpit, offering the advantages of a twin-engined craft in terms of visibility and armament. Unfortunately, this proved to be impractical since the Taurus engine was air-cooled.

In March 1941, Saab was authorized to resume work on the fighter project. By this time, technology had out-stripped the original Ll3 concept and a new liquid-cooled Daimler-Benz engine was available as though made to order. The modified design — the J21 — was presented to the Air Force chiefs on 1 April 1941.

The design was a cantilever low-wing monoplane having moderate wing sweep, with central fuselage nacelle to accommodate the pilot on an ejection seat. Power was a rear-mounted powerplant in pusher configuration, twin booms extending aft from the wings with twin fins and rudders united by the tailplane with elevator, and retractable tricycle landing gear.

The first of three Saab-21A prototypes was flown on 30 July 1943 and these, like a few early production aircraft, were powered by the imported Daimler-Benz DB 605; all subsequent production had a Swedish licence-built version of this engine.

 

 


The first operational aircraft was delivered to F8 Wing at Barkaby on 1 December 1945.

When introduced into service in late 1945 as the J21A-1 the new type was the only pusher-engined fighter to become operational during World War II, being followed by the generally similar J21A-2 and, finally, by the A21A attack aircraft, these three versions being built to a total of 299 before production ended in 1948.

Continuous improvements were made and a bomb-carrying version, the J21A-3, made its debut on 22 May 1947.

The A21A had the same armament as the J21A fighter, was equipped to carry rockets or light bombs on under-wing racks, and had provision for the installation of a ventral gun pack housing eight 13.2mm machine-guns.

Although increasing the speed was the first priority of the plane’s designers at this time, all attempts to achieve this aim using piston engines were abandoned with the advent of the jet engine in late 1945, and four J21A-ls were modified in an initial attempt to adopt the new technology.

Svenska Aeroplan adapted its Saab-21 design to accept the installation of a de Havilland Goblin gas turbine. This seemed a simple way to gain experience with this form of powerplant and, at the same time, extend the performance capability of the proven Saab-21 design; however, it was to prove rather more difficult a process than had been anticipated. The redesign affected 50% of the airframe rather than 20% as had been anticipated. The first requirement was for the aft fuselage nacelle to be widened to accept the new engine and the tailplane moved to the top of the fin to be clear of the jet efflux. It was also decided that because of the higher performance of this aircraft some structural strengthening was essential, and as there was no longer any need to be concerned about propeller ground clearance the landing gear struts were shortened. In this form the first Saab-21R prototype was flown initially on 10 March 1947.

saab-21r
J-21R


Almost two years elapsed before all development problem fixes had been finalised, the first deliveries of production aircraft starting during February 1949.

The original Saab-21 production order had been for 120 aircraft, but because of delay in its development, a programme for the specially-designed turbojet-powered Saab-29 was well advanced, with a result that the Saab-21R order was reduced to only 60 aircraft. These were produced as the J21RA with a 1361kg thrust de Havilland Goblin 2 engine, and J21RB with a licence-built Goblin turbojet, 30 of each being built. After comparatively short service in the fighter role, all were converted as attack aircraft, redesignated A21R and A21RB respectively, and carrying 10 100mm or five 180mm Bofors rocket projectiles, or 10 80mm anti-tank rockets.

In all, 298 J21s were built. The last of these was retired from service on 23 July 1954, al-though the J21R continued to fly until 4 April 1957.

J21A
Engine: Daimler Benz 605B, 1475 hp / 1100kW
Span: 11.64 m (38 ft 2.25 in)
Length: 10.45 m (34 ft 3.5 in)
Height: 3.96 m / 13 ft 0 in
Wing area: 22.2 sq.m / 238.96 sq ft
Take-off weight: 4150 kg (13615 lb)
Empty weight: 3250 kg / 7165 lb
Maximum speed: 640 kph (398 mph)
Cruising speed: 495 kph (308 mph)
Landing speed: 145 kph (90 mph)
Range: 1500 km (930 miles)
Max. altitude: 11000 m (36090 ft)
Armament: 1 x 20mm cannon, 4 x 13.2mm machine-guns
Crew: 1

A21A
Engine: Daimler Benz 605B, 1475 hp
Span: 11.64 m (38 ft 2.25 in)
Length: 10.45 m (34 ft 3.5 in)
Take-off weight: 4413 kg (14478 lb)
Maximum speed: 640 kph (398 mph)
Cruising speed: 495 kph (308 mph)
Landing speed: 145 kph (90 mph)
Range: 1500 km (930 miles)
Max. altitude: 11000 m (36090 ft)

21RA
Engine: De Havilland Goblin 2 (2998 lb)
Span: 11.37 m (37 ft 3.75 in)
Length: 10.56 m (34 ft 7.75 in)
Take-off weight: 5033 kg (16512 lb)
Maximum speed: 800 kph (497 mph)
Cruising speed: 700 kph (435 mph)
Landing speed: 155 kph (96 mph)
Range: 900 km (560 miles)
Max. altitude: 12500 m (41010 ft)

21RB
Engine: De Havilland Goblin 3, 3307 lb / 1500kg
Span: 11.37 m (37 ft 3.75 in)
Length: 10.56 m (34 ft 7.75 in)
Height: 2.95 m / 10 ft 8 in
Take-off weight: 5033 kg (16512 lb)
Maximum speed: 800 kph (497 mph)
Cruising speed: 700 kph (435 mph)
Landing speed: 155 kph (96 mph)
Range: 900 km (560 miles)
Max. altitude: 12500 m (41010 ft)
Armament: 1 x 20mm cannon, 4 x 13.2mm machine-guns
Crew: 1

saab-21-ld
Saab 21



saab-21r-ld

Saab 21R

 

 


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