The SM.105 was initially designed as an improved version of the SM.104, but following the release of concepts of the Fairchild XC-120 and Miles M.68, the SM.105 was redesigned with a detachable cargo section with a capacity of 64 m3 (2,260 ft3). The cockpit was above the cargo bay. There were large doors both forward and aft. The useful load comprised eight horses and four assistants, or two cars. A civil version had 40 seats and a bar, with a fully glassed nose to "assure an uncommon view".
The most unusual feature of the aircraft was the detachable central fuselage, leaving the cockpit in the middle of the wing, similar to the CH-54 Tarhe helicopter of the 1960s. However conditions in 1947 were not favourable to this new project.
