The Saunders-Roe SR.177 was a 1950s project to develop a combined jet- and rocket-powered interceptor aircraft for the Royal Air Force and Royal Navy. The German Navy also expressed interest in the project, which was cancelled due to changes in Britain's military policies in 1957. A much larger development was studied under the SR.187 project for Operational Requirement F.155, but this work was also cancelled in 1957, after approximately 90% of the first prototype had been completed.