![[Airborne photo]](../img/saab/saabj21.jpg)
![[Side fuselage view]](../img/fvmus96/a21-2.jpg)
After the proposal had been handed in, Frid
Wänström pointed out that using a pusher
propeller, better vision across the nose and more
concentrated armament could be achieved. There would be one 20 mm cannon
and two 13.2 mm guns in the nose and one 13.2 mm gun in each boom.
Internal project
number for this fighter was L-13. Layout was a pusher prop
right behind the cockpit, twin booms and a tall landing gear with
nose wheel. Crew was a single pilot.
![[Underside view]](../img/fvmus96/a21.jpg)
As Saab at this time was
busy developing and manufacturing the bombers B 17 and B
18, both L-12 and L-13 were put on the back burner.
In 1941 the air force arranged for purchase and licence production of Daimler Benz DB 601 engines, and Saab was told to expect to use DB 601 and DB 603 engines for future projects.
The air force liked the project L-13, but realized there could be problems with its development. The conventional fighter J 22 (by Bo Lundberg) was put into production by the air force itself and Saab started projecting a conventional fallback fighter (J 23). Both it and the J 21 (and L-21 as L-13 was now known) were to be armed with one 20 cannon and four 13.2 mm guns.
In October 1941 the J 23 was chosen by the air force and work on J 21 was stopped, but in December J 23 was cancelled and J 21 definitely chosen.
In 1943 71 DB 605B engines of 1475 hp were purchased at the same time a licence production contract was signed. The first engine made in Sweden wasn't delivered until after the war and production continued until 1948.
The wing profile for J 21 which was significantly faster than previous Swedish aircraft was similar to the one on Hawker Tempest, in order to get laminar flow as far as possible.
![[Wing and gear view]](../img/malmen76/a21.jpg)
Since the propeller was placed behind the pilot, an escape
system was needed, the form chosen was an ejection
seat. (The J 23 would have had an ejection seat too.) It
was tried before the first flight of the prototype on 1943
July 30. First
real use, which was succesful, was 1946 July 29 after a mid-air collision
between a J 21 and a J 22. In all 25 emergency ejections
were performed from aircraft type 21, of which 23 were
successful.
Originally 484 were ordered, but with the purchase of Mustang the number was reduced to 422, but in the end only 298 were made. There were five production batches and three prototypes, one which didn't fly:
Number Delivery In service
made
J 21A-1 54 1945-46 -1949
J 21A-2 62 1946-47 -1953 Improved avionics. Swedish made 20 mm gun.
J 21A-2 62 1947-47 -1954
A 21A-3 60 1947-48 -1954 Primarily intended for ground attack.
A 21A-3 60 1948-49 -1954
The J 21A-1s were all retired at the beginning of 1949.
It was never a success as a fighter, but those designated
A 21 (A = Attack, ground attack) or even B 21 (B = Bomb)
made good service. They had the same armament as the
fighter version, but also provision for carrying rockets
and bombs with a bomb aiming sight, as well as two RATO
bottles.
An improved version, J 21B was envisioned in 1945. It was
to have three 20 mm cannons in the nose, a radar in the
starboard boom and better aerodynamics. It was to use the
same engine or possibly a DB605E. There has also been
references to a envisioned variant with a RR Griffon engine.
But of course it was
really time for jet engines by then.
Saab wanted to gain experience with jet engines, and
decided in 1945 to convert a few J 21A-1s to jet power
powered with de Havilland Goblin 2 engines which were
ordered from Enland.
The aircraft to be converted were taken from the assembly line before they were finished. Optimistically it was thought only 20% needed to be redesigned, but closer to 50% had to be changed. First prototype flew in 1947 March 10.
The main aerodynamic differences were the the tailplane were moved up to get away from the exhaust and the wing leading edge moved forward and made sharper. A totally new wing was cancelled on cost grounds.
The air force planned to order 120 but only 60 were ordered in 1947.
Number Delivery In service
made
(J)A 21RA 30 1950-50 -1953 English made engine
(J)A 21RB 30 1950-52 -1956 Swedish made engine
The J 21R (R = rea, reaction or jet) wasn't successful as
a fighter either. It was used as a ground attack aircraft
but had very limited range, with a maximum endurance of 46
min. With wing tip tanks it was increased to 100 min, but
loaded with rockets flying at low altitude the radius of
action was only 190 km.
J 21A-2 A 21A-3 A 21RB
Engine DB605B DB605B DH Goblin 3
1475 hp 1475 hp 1500 kp
Span 11.60 m 11.60 m 11.37 m
Lenght 10.45 m 10.45 m 10.55 m
Wing area 22.2 m2 22.2 m2 22.1 m2
Fuel
internal 510 l 510 l 890 l (of which 300 l in the wings)
external 2 x 160 l 2 x 400 l 2 x 400 l
Weight
empty 3330 kg 3346 kg 3090 kg
max TO 5200 kg 5200 kg 5615 kg
Speed
max 650 km/h 560 km/h 800 km/h
cruise 490 km/h 425 km/h 610 km/h
Altitude 10200 m 7500 m 12000 m
Range 1190 km 1650 km 900 km
Endurance 2.4 h 4.2 h 1.1 h (with external tanks)
Armament
20 mm cannon 1 1 1
13.2 mm gun 4 4 4 later changed to 12.7 mm
7.9 mm gun in pod 8
Bombs 1 x 600 kg
1 x 500 kg
1 x 250 kg
4 x 50 kg
Rockets 2 x 18 cm 5 x 18 cm
8 x 8/14.5 cm 10 x 8/10 cm
Max external load was 700 kg, which could mean one heavy bomb
plus four light (50 kg) bombs or rockets.
More information: Saab historical aircraft
Major source: Kontakt #99