It started as a private venture by the defunct Svenska Aero company when the company board contacted the Swedish Air Board asking them for guidelines and wishes for a fighter aircraft. As they didn't receive any answer, Svenska Aero contacted with foreign designers in order to get some guidance.
Designed by Carl Clemens Bückler, it was a conventional biplane powered by the Armstrong-Siddeley Jaguar 14-cylinder radial engine and featured a fixed landing gear plus a skid under the tail section. Fuselage was made of welded beams covered with fabric while fore and aft parts were covered in aluminium sheet and it had a fuel tank between the engine and cockpit.
The test pilot, Nils Söderberg, after having tested it, stated that it was the best airplane he had ever flown and, after that test, it was presented the first prototype to the press on 11th November 1929. The prototype was bought by the Swedish Air Force on 9th January 1930 and was given the designation J5 and on February 1930 the Air Board decided that it had to be powered by a Bristol Jupiter engine, forcing that way to redesign it, specially the front part and some fuselage parts. The reformed version received the name of J6 or Jaktfalken I. It was followed by a new order of 5 new aircrafts this time powered by Bristol Jupiter VII engines in 1930 but when tested, the vibrations produced by the engine were too much and, despite that the they tried to solve the problem, no solution was found. After that, Bückler redesigned the landing gear and redesigned it to be powered by the Bristol Jupiter VIIF, or Jaktfalk II which were delivered to the Swedish Air Force in 1932.
Further minor modifications in the windshield and stabilizer were carried out in 1933 when Svenska Aero was merged into Asja and delivered seven additional airplanes, calleb J6B, to the Swedish Air Force.
Initially all fighters were assigned to the F1 Squadron at Västeras air base, and later they were transferred to the F8 Squadron based at Barkarby air base in October 1938 to be used as trainers. During the Winter War, three aircrafts were given to Finland as part of the aid-programme and the rest were scrapped in 1941.
Sources:
1. https://en.wikipedia.org/wiki/Svenska_Aero_Jaktfalken
2. Salamander Books - The Complete Book of Fighters.
