Société Anonyme des Moteurs Gnome-Parigi, France 1914
After leaving 80 HP Lambda models, as the automatic entry valve into the piston crown gave birth to an inconstant working and the danger of explosion of the mixture contained in the carter, Gnome designed a new propulsor with a different type of power supply, named Monosoupape (monovalve).
The new type of head controlled valve allowed both the exhaust of combusted gases and the induction of pure air. The fuel, a rich mixture, reached the cylinder through a series of windows made in the cylinder barrel next to the lower dead point, with the valve closed for about half the stroke during the induction stage. The transfer was accelerated by the depression created in the very cylinder. The Monosoupape B was installed on Sopwith Pup, Nieuport Ni 28, Vickers FB 5 e FB 9, Avro 504 J, RAF FE 8 and Airco DH 2 aircrafts.