The SM.89 was intended to be a bomber/attack aircraft, something similar to Junkers Ju 88. The aircraft displayed some impressive features, but it was not a new project, rather an extrapolation from the earlier SM.84. The project utilized the wings, the aft fuselage and the mixed construction of the latter almost untouched, with a totally redesigned nose. The fuselage was made from a skeleton of steel tubes, covered with duralumin and wood back as far as the dorsal turret, the remainder of the fuselage being of wood and fabric construction. The wing was made of wood using three spars and a covering of compensate wood. The control surfaces comprised slats and flaps, and the ailerons, that were lowered partially with the flaps to increase lift.