Supermarine ScyllaThe Supermarine Scylla was a 1920s British biplane flying boat built by Supermarine.Design and developmentThe Scylla was designed by R. J. Mitchell, chief designer at Supermarine as an experimental wooden twin-engined biplane amphibian aircraft, in parallel with the Supermarine Swan design for a replacement for the Royal Air Force's Felixstowe F5s.