Not having enough with his already clumsy S.M.1 A3, René Moineau thought maybe more was better and decided to try the bimotor formula. Like in the S.M.1, this contraction had a water-cooled Salmson 9A radial engine in the middle of the fuselage connected to outboard propellers through shafts and gears but an additional Salmson 9A was added in the nose driving a conventional tractor propeller. The two engines were now cooled by enlarged radiators placed in both side at the middle of the fuselage. All that had a price: the weight rose and the upper wing span had to be increased; undercarriage needed strengthened too. All that just for starters: we are talking about a massive modification. Named the S.M.2, a single aircraft was built in 1918 as two-seat (instead of three) intended for the ground attack role. Tested with poor results: it was even less satisfactory than the original.