The Short Admiralty Type 81 was a series of British two-seat floatplanes built prior to the First World War, and used by the Royal Naval Air Service in the early years of the war. They were powered by 160 hp (120 kW) Gnome Lambda-Lambda 14 cylinder two-row rotary engines and had folding wings to aid storage on ship, hence the popular name Short Folder, shared with a number of other seaplanes made by Short Brothers.

The Gnome 7 Lambda was a French designed, seven-cylinder, air-cooled rotary aero engine that was produced under license in Britain and Germany. Powering several World War I-era aircraft types it was claimed to produce 80 horsepower (60 kW) from its capacity of 12 litres although recorded figures are lower.