| CPC F02C 7/36 (2013.01) [F01D 5/284 (2013.01); F01D 5/3084 (2013.01); F02C 3/073 (2013.01); F05D 2240/12 (2013.01); F05D 2240/30 (2013.01)] | 20 Claims |

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1. A gas turbine engine for an aircraft comprising:
an engine core comprising:
a first turbine, a first compressor, and a first core shaft connecting the first turbine to the first compressor;
a second turbine, a second compressor, and a second core shaft connecting the second turbine to the second compressor, the second turbine, second compressor, and second core shaft being arranged to rotate at a higher rotational speed than the first core shaft; the gas turbine engine further comprising:
a fan comprising a plurality of fan blades; and
a gearbox that receives an input from the first core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the first core shaft, wherein:
the total mass of the turbine, which includes the first turbine and the second turbine, is no greater than 17% of the total dry mass of the gas turbine engine, and a bypass ratio of the gas turbine engine at cruise conditions is in an inclusive range of from 12.5 to 16.
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