The Caproni Ca.133 was a three-engined transport/bomber aircraft used by the Italian Regia Aeronautica from the Second Italo-Abyssinian War until World War II. Originally developed as a civilian airliner and successor to the Ca.101, the Ca.133 prototype first flew in December 1934, and production began in 1935. The military versions of the aircraft were used as transports and light bombers and saw action on all fronts. A stretched transport version of the aircraft was produced as the Caproni Ca.148. Design Designed by ingegnere Rodolfo Verduzio, the Caproni 133 was aerodynamically and structurally an improved Ca.101. Like its predecessor, the Ca.101, was a robust and inexpensive aircraft, designed to be easily maintained in difficult conditions and economical to operate. It had a welded steel-tube structure, mixed construction, with metal and fabric covering, main wheel spats, flaps and modified tail surfaces. The wing was high-mounted, roughly elliptical, and made of wood and steel. The undercarriage was spatted and fixed. The aircraft was powered by three engines, one in the nose, and one under each wing mounted in faired nacelles, with NACA cowlings, supported by steel tubes. The civil version could accommodate up to 16 passengers. It was used by Ala Littoria. The military version was widely used by Regia Aeronautica, mostly in Italian East Africa. As a bomber it incorporated two small internal bomb bays where it could hold up to 500 kg (1,100 lb). Larger ordnance could be mounted externally. It was armed with four 7.7 mm (.303 in) Breda-SAFAT machine guns, one dorsal, one ventral, and two lateral. Bomber aircraft operated as military transports, redesignated Ca 133T, had their interiors modified to accommodate 18 fully equipped soldiers. Operational service Second Italo-Abyssinian War (1935–1936) The Ca.133 was well-suited for colonial use, and it became the most successful of all Italian colonial aircraft. The more advanced Savoia-Marchetti SM.81s were too valuable to be used in 'low level wars' and were also more costly. The war was thus fought mainly with the Ca.101, Ca.111 and Ca.133. Around 100 Ca.133s took part in the conflict, and as well as 'normal' bombing and strafing, they were often equipped with mustard gas and Phosgene chemical bombs.These weapons were forbidden by the Geneva Protocol of 1925, but in this war (and in Libya) the Italians ignored the convention. The Ca.133s were also used as transports to support the army, as well as reconnaissance aircraft. Without any air