The British Royal Air Force probably used rotary engines for longer than most other operators. The RAF's standard post-war fighter, the Sopwith Snipe, used the Bentley BR2 rotary as the most powerful (at some 230 hp (170 kW)) rotary engine ever built by the Allies of World War I. The standard RAF training aircraft of the early post-war years, the 1914-origin Avro 504K, had a universal mounting to allow the use of several different types of low powered rotary, of which there was a large surplus supply. Similarly, the Swedish FVM Ö1 Tummelisa advanced training aircraft, fitted with a Le-Rhone-Thulin 90 hp (67 kW) rotary engine, served until the mid thirties.