The Napier Lion was a massive commercial success for D. Napier & Son. It was ubiquitous being fitted in the majority of aircraft in the British Empire. Between the wars it powered over 150 different aircraft civil and miltary aircraft worldwide.
A 500 bhp Napier Lion engine powered a Supermarine Sealion flying boat which won the 1922 Schneider Trophy. Napier developed the Lion to produce 900 bhp for the 1927 Schneider race winner powering the Supermarine S5 seaplane at 281.6 mph. In 1929 the engine was supercharged to produce 1,350 bhp and briefly took the world air-speed record in the lovely Gloster VI “Golden Arrow” floatplane at 336 mph. Highly tuned racing versions of the Lion could reach 1,300 hp and were used to break a whole host of world records including height, air speed and long distance records on land sea and in the air. This included the water speed record of 100 mph in 1933 in Hubert Scott-Paine’s Miss Britain III a record for single engined boats which stood for 50 years. A Napier Lion engine is fitted into the famous Napier Railton racer which holds the lap record for Brooklands in perpetuity. Lions powered many of Sir Malcolm Campbell’s record breakers (incuding over 250 mph in 1932) and John Cobb’s 394 mph Railton Mobil Special in 1947 a record that stood until the 1960’s, well after the Lion engine had passed its prime.
A marine version of the Lion, unsurprisingly named the SeaLion, was fitted in high speed air-sea rescue launches operated by the RAF during WWII. Another use for the Lion were in propeller-driven motor sleighs which were used for high-speed transport and SAR duties on sea ice by the Finnish Air Force and Navy.
Whilst there are no Napier Lion engines flying today they can still be seen fitted in several racing cars and also demonstrated on an engine stand at events around the UK.