Armstrong Siddeley Sapphire
From Biocrawler, the free encyclopedia.
The Sapphire was a jet 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, an advanced axial flow design with an annular combustion chamber that developed over 10,000 lbf (4450kg). It powered the Gloster Javelin, Hawker Hunter, Handley Page Victor and English Electric Lightning. Production was also started under license in the United States by Wright Aeronautical as the J65, powering a number of US designs.
Design of the Sapphire started at Metropolitan-Vickers (Metrovick) in 1943, as a larger version of the F.2, which was also being re-designed for more power. The larger F.2 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. By this point the F.9 was developing about 7,500 lbf (33 kN), somewhat more than its competitor from Rolls-Royce, the Avon. Interest in the design was high, and it was considered as either the main or backup powerplant for most late-40s/early-50s British designs.
At about the same time the Ministry of Supply demanded that Metrovick exit the industry in order to reduce the number of companies they had to deal with. Their design team was quickly snapped up by Armstrong Siddeley. Although Armstrong Siddeley already had a turbine development of their own, it was focused entirely on turboprops, and the Metrovick team was a welcome addition. Work on the F.9 continued, now renamed the AASa.6. The engine was soon passing tests at ever-increasing power settings, becoming the first British engine to be rated at 10,000 lbf (44 kN).
Wright purchased a license for the Sapphire in 1950, with plans to have the production lines running in 1951. However a series of delays led to its service introduction slipping a full two years, by which point the Pratt & Whitney J57 was on the market and took many of the J65's potential sales. Nevertheless once it entered production it proved to be as good as the British versions, and along with the Martin B-57, its original target market, the J65 went on to power versions of the Republic F-84 and Douglas A-4.
