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Saab J 21 fighter

The J 21 was the beginning of a long tradition within the Saab company to come up with unconventional solutions on design problems. The Saab 21R (1947) was a Swedish twin-boom fighter/attack aircraft that was a jet-powered development of the piston-engined Saab 21? .. The layout of the J 21 provided the pilot good allround view and made it possible to install heavy armament in the nose of the aircraft. The prototype flew for the first time in 1943 and was one of the first aircrafts in the world to be equipped with an ejection seat. Total production reached approx. 300 aircraft and it served in the Swedish Air Force during 1945 – 1953. Today only a few J 21 is preserved in museums, among them is ”Röd Rudolf” at Flygvapenmuseum in Linköping.

Saab J 21, also called "Tvestjärten" was a Saab Swedish-built fighter aircraft. J 21 was in versions J 21A, J 21B and A 21, hunting and attack aircraft respectively and was in active service between the years 1945-1954, ie for a total of nine years. The aircraft was used only in Sweden. J 21B would be the last Swedish propeller plane before the jet age and J 21R.

J 21 is a low-wing aircraft constructed with two so-called tail booms and a propeller at the rear. For that reason, in an emergency, rescue from the aircraft could not be carried out by jumping, at least not if you wanted to get into strips as you were automatically sucked backwards by the speed wind into the propeller. Therefore, you needed to get higher up, away from the propeller and far back to avoid the rudder at the rear. Therefore, the J 21 became one of the world's first mass-produced aircraft with a catapult seat. The catapult seat was developed by Saab and propelled from the aircraft with a powder charge. The position of the propeller, behind the driver's cab, provided a clear view ahead and provided opportunities for weapons in the nose. This means that the sighting procedure takes place with the entire aircraft as sighting.

Another novelty with the 21's construction was the one with nose wheel stand. The nose wheel stand was tested by equipping a SK 14 with a prototype. The fact that the wheelbases became so high was due to the fact that they wanted to keep the risk of the propeller hitting the ground as small as possible. This also made the Saab 21 the first Swedish aircraft with a nose wheel stand. The cockpit of a Saab 21 is simple. With relatively few, but for its time state-of-the-art instruments and a long joystick. The 21 was also equipped with a line of sight indicator.

The engine in the Saab 21 is a Swedish-made Daimler-Benz DB 605B that is powered by 100 octane. This means that the Saab 21 has a top speed of about 250km / h. It also had a maximum altitude of about 7,500m.

Unfortunately, the Saab 21 did not work as well as fighter jets and the production of the J 21 was stopped. In November 1945, the SAAB received an order from the Air Force to stop work on aircraft with piston engines and nationally developed turbojet engines. Instead, the attack version was manufactured where it did not matter so much that the aircraft was somewhat difficult to maneuver and had poor climbing ability.

At the end of the 1940s, Saab rebuilt 64 Saab 21As for jet engine operation. They were given the designation Saab 21R, R stands for reaction engine or rea engine as jet engines were called. It must be said that back in 1933, engineer Lisholm patented the first gas turbine engine in Sweden. According to his project in 1934, the Bofors company built a small, but quite efficient turbojet engine for bench tests. During the war years, the company SFA (Svenska Flugmotor AB), whose chief engineer was Lisholm, developed a powerful and quite reliable engine P / 15-54 with a two-stage centrifugal compressor, a four-stage turbine and an annular combustion chamber and a thrust of about 1820 kg. In 1944-45, SAAB designed the RX-1, RX-2 and R-101 fighters for this engine. The first of them was similar to the J-21A, the second, which received the unofficial name "The Merry Widow" - to the English "Vampire", and the R-101 was very reminiscent of the American P-80 "Shooting Star" fighter. To the credit of Swedish engineers, they created their projects on their own, without having information from the UK and the USA.

In order not to create a new aircraft for the installation of a turbojet engine, and to start retraining the flight and technical personnel for jet technology, as soon as possible, it was decided to use the J-21 for its installation (solving a similar problem, they did the same in the Yakovlev Design Bureau, installing on the Yak -3 turbojet engine, resulting in the Yak-15).

As a fighter, the J-21R demonstrated low combat effectiveness. The decision was ripe to convert the next 30 aircraft into attack aircraft with reinforced cannon and missile-bomb armament. This is how a modification of the J-21RB with the Goblin III turbojet engine (RM-1A) with a thrust of 1500 kg appeared.

The age of the J-21A and J-21R aircraft was short-lived. The last piston fighters in Sweden were removed from service in 1953. They were replaced by new jet fighters. J-21R served only until mid-1954, when they were finally replaced by A-29B attack aircraft. Until the end of the 50s, only a few J-21Rs of the F17 training wing at Kalinge were in operation. The Air Force did not save any of the 64 copies built, despite the fact that the J 21R was the first Swedish jet aircraft. The J-21R on display at the Swedish Aviation History Museum in Linköping is a replica rebuilt from a piston J 21.