The aircraft did not have a nose engine, unlike many contemporary Italian designs. The SM.89 was a two-engine aircraft so that the nose could be used to house weapons. The nose section was rounded, short, and inclined sharply to provide good visibility for attacks on surface targets. The weaponry was mainly based on the 37 mm (1.46 in) Breda anti-aircraft guns, used in the anti-tank and anti-ship roles. Three 12.7 mm (.50 in) Breda machine guns were also fitted in the nose. A further Breda machine gun was also fitted in the dorsal turret, and another was in a new model turret, a remote-controlled one, in the ventral position.