Saab 21R

Saab 21R

Saab 21R in flight
Role	Fighter and attack aircraft
Manufacturer	Saab AB
Designer	Frid Wänström
First flight	10 March 1947
Introduction	1950
Retired	1956
Status	retired
Primary user	Swedish Air Force
Produced	1950–1952
Number built	64
Developed from	Saab 21

The Saab 21R was a Swedish twin-boom fighter/attack aircraft made by Saab. It was a jet-powered development of the piston-engined Saab 21 which along with the Russian Yakovlev Yak-15 was one of the only two jet fighters successfully converted from a piston-powered aircraft.^[1]

As a fighter, its service designation in the Swedish Air Force was J 21R, and saw service in the late 1940s.

Design and development

In early 1945, Saab launched a project to determine how to provide the J 21A with a jet engine to get the experience of jet engines and flying at high speeds. The goal was to catch up with the development of jet aircraft, which were moving ahead fast in England, where, among others, de Havilland already had the de Havilland Vampire in production.

When the project started, the engine choice was an open question. However, as the project progressed it became possible to buy a "Goblin 2" jet engine from de Havilland Engine Company, along with the license to manufacture in Sweden. This engine became the Air Force's first Jet Engine, RM1. The rebuilt J 21A received type designation J21R. First flight with Saab's first jet took place on 10 March 1947.

Changes from the J 21A version

Because of the engine exhaust position, the stabilizer had to be raised, which meant that the tail had to be redesigned. Measures to improve the aerodynamic design of the aircraft were carried out, for example, curved front glass in the canopy and a refined wing leading edge. Airbrakes were introduced in the form of an upward and a downward flap on the outer wing's trailing edge. Ejection seat improvements were made to enable ejections at high speed. Fuel volume increased significantly with the use of tanks in the middle wing and large wingtip tanks.

The attack version A 21R added 14.5 cm attack rockets placed under the middle wing. Furthermore, an alternative external machine gun pod was created. A big sensation was that it was possible to fire all 13 weapons at the same time. This was an interesting "sensation" for the pilot as well.

A production of 124 planes was planned originally, including four prototypes. When experience with the type as a fighter was gained with the F10 wing it was concluded that all aircraft needed to be changed to attack aircraft. The production series was then reduced to 64 aircraft. Of these, 34 were J21RA fitted with the Goblin 2 engine, RM1, with 1360kp of thrust.

30 J21RB with a Swedish-made Goblin 3 engine, RM1A, with a thrust of 1500kp.

Operational history

The first prototype Saab 21R first flew on 10 March 1947,^[2] almost 2 years after the Second World War. The aircraft first entered service with F 10 in August 1950. Although the type was originally intended as a fighter aircraft, a newly developed fighter, the Saab J 29 first flew in October 1948, the number to be produced was halved from 120 to 60, and eventually all 21Rs were converted to attack aircraft as A 21RA or the A 21RB depending on the engine type.

Variants

J 21RA / A 21RA: First production series, powered by British-built engines, 34 built in 1950 (including four prototypes), retired in 1953.^[3]
J 21RB / A 21RB: Second production series, powered by Swedish-built engines, 30 built between 1950 and 1952, retired in 1956.

Operators

Sweden

Swedish Air Force
- F10 Ängelholm, 1949–51: J21RA
- F7 Såtenäs, 1950–54: A21RA/B
- F17 Kallinge, 1954–56: A21RA/B

Specifications (Saab 21RA)

Data from Attack and Interceptor Jets^[4]

General characteristics

Crew: One
Length: 10.45 m (34 ft 3 in)
Wingspan: 11.37 m (37 ft 4 in)
Height: 2.90 m (9 ft 8 in)
Empty weight: 3,200 kg (7,055 lb)
Max. takeoff weight: 5,000 kg (11,023 lb)
Powerplant: 1 × De Havilland Goblin 2 turbojet, 13.8 kN (3,100 lbf)

Performance

Maximum speed: 800 km/h (497 mph)
Range: 720 km (450 mi)
Service ceiling: 12,000 m (39,400 ft)
Takeoff roll: 650 m (2,133 ft)

Armament

1x 20 mm Bofors cannon
4x 13.2 mm M/39A heavy machine guns
Centerline pod for an additional 8x 13.2 mm M/39A heavy machine guns
Wing racks for either: 10x 100 mm or 5x 180 mm Bofors rockets, or 10x 80 mm anti-tank rockets.

References

Notes

↑ Gunston 1995, p. 472
↑ Billing 1983, p. 22.
↑ Widfeldt 1966, p. 9.
↑ Sharpe 1999

Bibliography

Andersson, Hans G. Saab Aircraft since 1937, 1st ed. London: Putnam, 1989. ISBN 0-85177-831-3.
Billing, Peter. "Saab's Jet Debutant". Air Enthusiast, Twenty-three, December 1983 – March 1984, pp. 20–30. Bromley, UK: Fine Scroll. ISSN 0143-5450.
Gunston, Bill. The Osprey Encyclopedia of Russian Aircraft 1875–1995. London: Osprey, 1995. ISBN 1-85532-405-9
Sharpe, Michael. Attack and Interceptor Jets. London: Friedman/Fairfax Publishers, 1999. ISBN 1-58663-301-5.
Widfeldt, Bo. The Saab 21 A & R (Aircraft in Profile number 138). Leatherhead, Surrey, UK: Profile Publications, 1966.

External links

Wikimedia Commons has media related to Saab J21R.

SAAB 21 story
J.21R in the Air - a 1948 Flight article on flying the SAAB J.21R

SAAB/Saab aircraft

Military aircraft	17 18 21 21R 29 32 35 36 37 38 39 105 210 Tp 100A/C S 100B/D

Civil aircraft	90 91 107 340/340 AEW&C 2000 MFI-15

Aircraft names	Argus Draken Gripen Lansen Safir Safari Scandia Tunnan Viggen

Swedish Air Force military aircraft designations 1940–present

1-25	B/S/T/Tp 16 Sk 16 B/S 17 B/S/T 18 J 19 J 20 A/J 21 A/J 21R J/S 22 J 23 B/J 24 Tp 24 Sk 25

26-50	Sk 26 B/S 26 J/S 26 J 27 A/J/Sk 28 A/J/S 29 J 30 S 31 A/J/S 32 J 33 J 34 J/S/Sk 35 A 36 AJ/JA 37 A/Sk 38 JAS 39 Tp 45 Tp 46 Tp 47 Sk 50

51-100	Fpl 51 Tp 52 Tp 53 Fpl 54 Tp 54 Tp 55 Sk 60 Sk/Fpl 61 Tp 78 Tp 79 Tp 80 Tp 81 Tp 82 Tp 83 Tp 84 Tp 85 Tp 86 Tp 87 Tp 88 Tp 89 Tp 91

100-	Tp 100 Tp 101 Tp 102 Tp 103

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