The Supermarine Type 545 was a design for a jet fighter to replace the Supermarine Swift.
The Type 545 was designed in response to Specification F/105D2, which called for a supersonic fighter to replace the Swift. Two designs were suggested, the Supermarine Type 545 and the Hawker P.1083 (this was soon cancelled). Supermarine were awarded a contract to produce two prototypes in February 1952, with the first to be ready in 1954.
The Type 545 had an area ruled fuselage, with a flat base and curved sides. It was given a swept back wing with different degrees of sweep along its length. The thick inner section, which also carried the main wheels, swept back at 50 degrees. This was reduced to 30 degrees at the outer section, to improve high altitude performance. It had movable swept tail surfaces. The air intake was in the nose.
The Type 545 was to be powered by the Rolls-Royce Avon RA14, which was expected to provide 9,500lb thrust and 14,500lb thrust with reheat. This engine was expected to allow the Type 545 to reach Mach 1.3, but as work on the design continued the speed estimate was reduced.
Supermarine suggested installing more powerful Avon RA35R or RB106 engines in the second prototype, and expected this version to reach Mach 1.68. However this was a period of rapid development, and by the end of 1954 it was clear that the rival English Electric P1 was much more promising. As a result the second prototype was cancelled on 9 November 1954. Work on the first prototype continued, but the aircraft was now only expected to serve as a research aircraft. The entire project was cancelled early in 1955, and the largely complete first prototype was used as an instructional airframe until the early 1960s, when it was scrapped. The English Electric design lived up to expectations, and entered service as the Mach 2 capable English Electric Lightning.