The Supermarine Sea Urchin was an unbuilt British racing biplane flying boat designed by the Supermarine Aviation Works to compete in the 1924 Schneider Trophy. It was to be a single seat biplane, powered by a Rolls-Royce Condor V-12 water-cooled engine buried in the fuselage, driving a pusher propeller mounted on the upper wing via geared shafts. It was abandoned without being built owing to problems with the engine and the transmission required to drive the propeller.^[1]

Data from Supermarine Aircraft Since 1914^[1]

General characteristics

• Crew: 1
• Powerplant: 1 × Rolls-Royce Condor V-12 water-cooled piston engine, 600 hp (450 kW) driving the propeller through bevel gearboxes and a transmission shaft
• Propellers: 4-bladed fixed-pitch pusher propeller

• List of flying boats and floatplanes

• Andrews, Charles Ferdinand; Morgan, Eric B. (1981). Supermarine Aircraft since 1914. London: Putnam. ISBN 978-03701-0-018-0.