Cosmos Mercury


The Cosmos Mercury was a fourteen-cylinder twin-row air-cooled radial aeroengine. Designed by Roy Fedden of Cosmos Engineering, it was built in the United Kingdom in 1917. It produced 347 horsepower. It did not enter production; a large order was cancelled due to the Armistice.

Design and development

Built in Fishponds, Bristol by Brazil-Straker under the direction of Roy Fedden, the Mercury featured an unusual crankshaft and connecting rod arrangement that dispensed with the more normal design of a single master rod linking to individual rods for each cylinder. It was said to run well without vibration and set an unofficial time to climb record while fitted to the Bristol Scout F, the aircraft achieving 10,000 ft in 5.4 minutes and 20,000 ft in 16.25 minutes.
An Admiralty order for 200 engines was placed in 1917 but was later cancelled by Lord Weir due to the end of World War I, it is also stated that Lord Weir had a preference for the ABC Dragonfly.
The name was re-used by Fedden for the later nine-cylinder Bristol Mercury radial engine.

Applications