In 1938, ASJA (AB Svenska Järnvägsverkstädernas Aeroplanavdelning) offered to build a trial aircraft for the air force, either Gassner F-1 or their own L 10 which had been started in 1937. As Fieseler Storchs had been purchased for artillery spotting, that requirement was already filled, and the air force ordered two ASJA L 10s, designated P 7 (P = prov, trial).
The L 10 had mostly been designed by the 40 Americans working for ASJA/SAAB. It was a modern all metal design with flush rivets and in some respects was similar to Kingfisher and Helldiver.
As a dive bomber, the wing had to be strong, so the landing gear was not retracted into the wing, but folded back under it, covered by an aerodynamic fairing. When lowered, it was intended to be used as an airbrake (which had been a good solution if the hydraulic system had been powerful enough to extend the gear quickly and evenly). Skis could also be fitted. Later there was also a floatplane version.
It had a very roomy cockpit for the crew of two, the pilot and the observer/radio operator who could slide his seat back and forward between his different work stations. Fixed armament was two forward firing 8 mm guns in the wings, and one for the radio operator.
The air force had assigned the designation S 15 for the reconnaissance version and B 8 for the bomber. But at this time they figured out it would be more logical to give each aircraft type a single number, and Saab L 10 was the first to be given a number in this series: B 17.
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