Armstrong Siddeley Sapphire

The Armstrong Siddeley Sapphire was a British turbojet engine produced by Armstrong Siddeley in the 1950s. It was the ultimate development of work that had started as the Metrovick F.2 in 1940, evolving into an advanced axial flow design with an annular combustion chamber that developed over 11,000 lbf (49 kN). It powered early versions of the Hawker Hunter and Handley Page Victor, and every Gloster Javelin. Production was also started under licence in the United States by Wright Aeronautical as the J65, powering a number of US designs.

Design and development

Design evolution of the Sapphire started at Metropolitan-Vickers (Metrovick) in 1943 as an offshoot of the F.2 project. With the F.2 reaching flight quality at about 1,600 lbf (7,100 N), the Metrovick engineers turned to producing larger designs, both an enlarged F.2 known as the Beryl, as well as the much larger F.9 Sapphire. (The names were chosen after a decision to use gemstones for future engine names). The Beryl was soon running and eventually developed 4,000 lbf (18 kN) thrust, but the only project to select it, the Saunders-Roe SR.A/1, was cancelled.