Rolls-Royce Conway
| Conway | |
|---|---|
 |
|
| RCo.17 Mk201 | |
| Type | Turbofan |
| Manufacturer | Rolls-Royce Limited |
| Major applications |
Boeing 707 Douglas DC-8 Handley Page Victor Vickers VC10 |
The Rolls-Royce RB.80 Conway was the first by-pass engine (or turbofan) in the world to enter service. Development started at Rolls-Royce in the 1940s, but it was used only briefly in the late 1950s and early 1960s before other turbofan designs were introduced that replaced it. The Conway powered versions of the Handley Page Victor, Vickers VC10, Boeing 707-420 and Douglas DC-8-40. The name "Conway" is an Anglo-Saxon permutation of River Conwy, in Wales, in keeping with Rolls' use of river names for gas turbine engines.
In early jet engines the exhaust was much faster and hotter than it had to be (contrary to the ideal Froude efficiency) for efficient thrust; capturing some of that energy would improve the fuel economy of the engine. The turboprop is an obvious example, which uses a series of additional turbine stages to capture this energy to power a propeller. However, there is a tradeoff in propeller efficiency compared to forward speed, so while the turboprops are efficient engines, they are only efficient at speeds of up to 500 mph (800 km/h; 430 kn). This meant there was a sweet spot between the high efficiencies of the turboprop at low speeds and the jet at high speeds that was not being directly addressed. This spot, between about 450 mph (720 km/h; 390 kn) and 700 mph (1,100 km/h; 610 kn), was precisely where the vast majority of commercial jet aircraft spent most of their time.
The basic concept of bypass had been studied from the earliest days of jet engine design. Alan Arnold Griffith had proposed a number of different bypass engine designs as early as the 1930s while he and Hayne Constant were trying to get their axial-flow jet engines working at the Royal Aircraft Establishment. Frank Whittle's Power Jets also studied a number of bypass configurations. However, the need to get jet engines into service during the war meant this work had to be put aside in favour of the simpler turbojet designs with shorter introduction times. The ending of the war changed priorities dramatically and, by 1946, Rolls-Royce agreed that existing engines like the Rolls-Royce Avon were advanced enough that it was time to start work on new concepts like bypass.
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