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The Rolls Royce Ultrafan is the largest and most efficient engine to allow multiple turbine speeds. The turbines behind the main fan are small and allow more air to pass straight through, while a planetary gearbox "allows the main fan to spin slower and the compressors to spin faster, putting each in their optimal zones."
The Rolls–Royce Conway turbofan engine, developed in the early 1950s, was an early example of a bypass engine. The configuration was similar to a 2-spool turbojet but to make it into a bypass engine it was equipped with an oversized low pressure compressor: the flow through the inner portion of the compressor blades went into the core while ...
In July, Rolls-Royce was to supply its Trent 600 for the 767-400ERX and Boeing 747X, while the European Union was limiting the Engine Alliance offer on quadjets. [46] The 68,000–72,000 lbf (300–320 kN) Trent 600 was scaled from the Trent 500 with a swept fan diameter raised to 2.59 m (102 in) for a higher bypass ratio and lower fuel burn.
The Rolls-Royce Conway, the world's first production turbofan, had a bypass ratio of 0.3, similar to the modern General Electric F404 fighter engine. Civilian turbofan engines of the 1960s, such as the Pratt & Whitney JT8D and the Rolls-Royce Spey, had bypass ratios closer to 1 and were similar to their military equivalents.
Rolls-Royce are currently developing the Ultrafan which employs much of what is described above. [5] [6] In the 1980s the General Electric GE36 Unducted Fan (UDF), which actually flew on a McDonnell Douglas MD-80, employed two rows of contra-rotating variable pitch fan blades, albeit without any fan casing because it was a prop-fan engine.
The Rolls-Royce Trent 700 from the 1990s, with a pressure ratio of 36:1 and 3 separate compressor rotors, needs 3 rows of variable blades and 7 bleed valves. In the beginning higher pressure ratios had to be obtained with many stages because stage pressure ratios were low, about 1.16 for the J79 compressor which needed 17 stages. [ 58 ]
The Trent 900 is an axial flow, high bypass turbofan with the three coaxial shafts of the Rolls-Royce Trent family. The 2.95 m (116 in) fan with swept blades is driven by a 5-stage LP turbine, the 8-stage IP compressor and the 6-stage HP compressor are both powered by a single stage turbine, with the HP spool rotating in the opposite direction of the others.
The Rolls-Royce BR700 is a family of turbofan engines for regional jets and corporate jets. It is manufactured in Dahlewitz , Germany , by Rolls-Royce Deutschland : this was initially a joint venture of BMW and Rolls-Royce plc established in 1990 to develop this engine.