included the procurement of foreign-sourced aircraft as well as the local development of new, modern designs. However, as a consequence of the war, few nations at war were willing to supply fighters to a neutral country, while Sweden's own production capability would be insufficient until at least 1943. As a consequence, Sweden was forced to purchase already obsolete Fiat CR.42 biplanes from Italy as an interim measure, and which were of little value against modern monoplane fighters. Accordingly, SAAB began looking at solutions to various anticipated production problems for their proposed fighter. Design The SAAB J 21 needed a top speed of at least , which required a powerful engine. It was decided to substitute the Taurus engine for the American Pratt & Whitney R-1830 Twin Wasp radial engine. However Svenska Flygmotor was also asked to provide an alternative to the Twin Wasp. Options were limited by the urgency involved, leaving a license-produced engine as the only option. Accordingly, a locally built version of Germany's new Daimler-Benz DB 605B inline engine was selected, however, due to the DB 605B's lack of maturity, a great deal of refinement and modification by Swedish engineers was required to ready it for operational use. The SAAB 21 was an unorthodox twin-boom low wing pusher configuration fighter aircraft with a tricycle landing gear, and a heavy forward-firing armament. Several recent innovations were incorporated into its design, including an ejection seat for the pilot while the pusher layout later allowed the type to be readily re-engined with a turbojet. The advantages of a pusher design include an unobstructed forward view for the pilot, and the armament can be concentrated in the nose, however, a major drawback is difficulty in making an emergency exit as the pilot could get drawn into the propeller blades. Many solutions were examined, such as jettisoning either the propeller or the engine via explosive charges prior to bailing out, before it was decided to adopt an ejection seat developed by Swedish defense firm Bofors, in parallel with the fighter. The J 21 was one of the first operational aircraft in the world with an ejection seat. The wing of the 21 was built around a SAAB-designed laminar airfoil. As the wings could not readily accommodate the main landing gear when retracted, wells were provided in the tail booms, aft of the rear wing spar. To reduce drag, coolers and ducts for the