Blue Steel stand-off bomb, 1960.

The operational Blue Steel stand-off bomb carried Britain's nuclear deterrent between 1964 and 1975. Each was carried beneath a Vulcan or Victor aircraft and air-launched at altitude. Blue Steel used a Stentor rocket engine to accelerate to a maximum velocity of Mach 2. Stentor technology was subsequently used in the Gamma engines of the Black Knight ballistic test vehicle and Black Arrow satellite launcher. The Science Museum's Blue Steel is a test vehicle and is fitted with a Double Spectre rocket engine.