The SM.91 might be called the Italian P-38 as it was a twin-engined, twin-boom long-range escort fighter, but it differed from its American counterpart in having a crew of two. Designed in 1941 and competing with the Caproni Ca 380 Corsaro (also a twin-boom design) for production orders, the SM.91 flew for the first time on March 10, 1943, powered by 1475 h.p. Daimler-Benz DB 605A-l twelve-cylinder inverted vee engines. Only one prototype was finished. One of the few all-metal Savoia-Marchetti aircraft, it mounted three forward-firing 20-mm. Mauser MG 151 cannon in the central nacelle and two similar weapons in the wing roots. Four 220-lb. or 353-lb. bombs or a single 1100-lb. bomb (or 218-gal. drop-tank) could be carried externally on racks below the wings and central nacelle. Empty and loaded weights were 14,110 lb. and 19,600 lb. Maximum speed was 363 m.p.h. at 22,960 ft., cruising speed 320 m.p.h., service ceiling 36,090 ft., and range 994 miles. Climb to 19,680 ft. required 8 min. 30 sec. Dimensions were: span 64 ft. 7 1/2 in., length 43 ft. 5 3/4 in., height 12 ft. 7 1/2 in., and wing area 449.5 sq. ft.