The Savoia Marchetti S.M.84 was designed by Alesandro Marchetti to be a replacement for the S.M.79. The S.M.84 kept the wing design but improved the fuselage and added more powerful engines.
The S.M.84 had a wooden and steel tube frame with fabric, plywood, and aluminum making up the skin.
The landing gear was retracted into the engine housing.
The bombs were carried in the fuselage and under the wings. Only 2,000 lbs of bombs could be carried internally. Two torpedoes could be carried externally.