In July 1942, the Regia Aeronautica requested designs for a new aircraft, propelled by the DB605 engine, capable of flying at 620 km/h (385 mph) with a range of 1,600 km (995 mi). The armament should consist of six MG 151 cannons in the nose and wings and a 12.7 mm Breda-SAFAT machine gun as a defensive weapon. It should have a 800 kg (1,760 lb) bombload. Savoia Marchetti proposed the SM91, a derivative of its SM88 twin boom plane, and the SM.92.