Two propellers connected by right-angle bevel gears to crankshafts at the front and back of a water-cooled 230hp Salmson radial mounted cross ways in the fuselage. Sounds complicated, don’t you think? Oddly, the S.M.1 saw a limited production in WW1. It turned out to be an annoyance. The licence-built Sopwith 1½ Strutter was sure better .