The Su-8 was of mixed construction. The cockpit area was armoured, with an aluminum mid-fuselage and a wooden monocoque tail. The wings were of steel and aluminum construction with plywood outer sections. The twin rudders were of all-metal construction. In addition to the cockpit, the engines, the fuel tanks and the oil coolers were fully armoured, with a total armour weight of 1,680 kg (3,705 lb), more than twice as heavy as the armour shell on an Ilyushin Il-2. Armament was 4 45mm cannon under the airplane, 4 37mm cannon and 8 .30 cal machine guns in the wings, 1 .30 cal machine gun in the ventral position, 1 .50 cal machine gun in a dorsal turret, and up to 3,085 lbs of bombs.