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The UltraFan is a geared turbofan with a variable pitch fan system that promises at least 25% efficiency improvement. [84] The UltraFan aims for a 15:1 bypass ratio and 70:1 overall pressure ratio. [85] The Ultrafan keeps the Advance core, but also contains a geared turbofan architecture with variable-pitch fan blades.
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 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 first geared turbofan engine was created in 1970. [3] However, economically scaling the idea from small engines to medium and large ones was not possible until the 21st century.
The Rolls-Royce Trent 7000 is a high-bypass turbofan engine produced by Rolls-Royce, an iteration of the Trent family powering exclusively the Airbus A330neo.Announced on 14 July 2014, [2] it first ran on 27 November 2015. [1]
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.
Mockup with compressor and turbine cutaway. After the budget of NASA on aeronautics research was severely cut at the start of 2006, Pratt & Whitney committed to spend $100 million a year on the geared turbofan (GTF) development for the next generation of single-aisle airliners, focused on the 25,000–35,000 lbf (110–160 kN) thrust range. [9]
The Rolls-Royce Trent XWB is a high-bypass turbofan produced by Rolls-Royce Holdings.In July 2006, the Trent XWB was selected to exclusively power the Airbus A350. [2] The first engine was run on 14 June 2010, [3] it first flew on an A380 testbed on 18 February 2012, [4] was certified in early 2013, [5] and first flew on an A350 on 14 June 2013. [6]