Proteus

The Bristol Proteus was the Bristol Engine Company's first mass-produced gas turbine engine design, a turboprop that delivered just over 4,000 hp (3,000 kW). The Proteus was a reverse-flow gas turbine. Because the second turbine drove no compressor stages, but only the propeller, this engine was classified as a free-turbine. It powered the Bristol Britannia airliner, small naval patrol craft, hovercraft and electrical generating sets. It was also used to power a land-speed record car, the Bluebird-Proteus CN7. After the merger of Bristol with Armstrong Siddeley the engine became the Bristol Siddeley Proteus, and later the Rolls-Royce Proteus. The Proteus was to have been superseded by the Bristol Orion which would have given a Britannia a 75% increase in power for cruising faster. Design and development The Proteus was to power a very large airliner for use after the war. Design work started in September 1944 with its free turbine and propeller gearbox based on the earlier Bristol Theseus engine. The compressor had 12 axial and 2 centrifugal stages. The gas generator was built as a turbojet, and called the Bristol Phoebus, to speed development of the engine by not hindering it with gearbox problems. It was test-flown in May 1946 fitted to the bomb bay of an Avro Lincoln, performance was poor and the first centrifugal compressor stage was removed. The first Proteus, the Proteus 1, also ran with the original compressor, as first tested in the Phoebus, but by 1950 had been redesigned as the Proteus 2 with only a single centrifugal stage. The Proteus 2 (Mk.600 series) was supposed to produce 3,200 shp and weigh 3,050 lb. It was overweight and underpowered, weighing 3,800 lb producing 2,500 shp, and plagued with mechanical problems with virtually every part including compressor blades, turbine blades and bearings which failed at frequent intervals even at low power levels. This led to the famous quote of Proteus Chief Engineer Frank Owner to Chief Engineer of the Engine Division Stanley Hooker: "You know, Stanley, when we designed the Proteus I decided we should make the engine with the lowest fuel consumption in the world, regardless of its weight and bulk. So far, we have achieved the weight and bulk!" The redesigned Proteus 3 (700 series) gave 3,780 shp and weighed nearly 1,000 lb less than the previous design. It came too late for the first prototype Britannia and Saunders-Roe Princess flying-boat though.