Efficient gas turbine engine installation and operation

A gas turbine engine for an aircraft comprising:

• an engine core comprising a turbine comprising a plurality of turbine blades, a compressor comprising a plurality of compressor blades, and a combustor;
• a fan comprising a plurality of fan blades;
• and
• a gearbox that receives an input from a core shaft that is connected to at least a part of the turbine, the gearbox configured to drive the fan at a lower rotational speed than a rotational speed of the core shaft, wherein:
• a bypass duct is defined radially outside the engine core, with a leading edge of a splitter defining a point at which flow splits into a core flow and a bypass flow during operation of the gas turbine engine;
• a core compressor aspect ratio is defined as a ratio of an axial distance between the leading edge of the splitter and a leading edge of a tip of a downstream-most compressor blade to a radius of the leading edge of the splitter, the radius of the leading edge of the splitter being measured from a centerline axis of the gas turbine engine, the core compressor aspect ratio being in a range of 1.7 to 3.4;
• a hub-to-tip ratio defined as a ratio of a radius of a fan blade of the plurality of fan blades at a hub to the radius of the fan blade at the tip is in a range of 0.27 to 0.35;
• a fan root pressure ratio, defined as a ratio of a mean total pressure of a flow at a fan exit that subsequently flows through the engine core to the mean total pressure of a flow at a fan inlet, is no greater than 1.3 at cruise conditions;
• a fan tip pressure ratio, defined as a ratio of the mean total pressure of the flow at the fan exit that subsequently flows through the bypass duct to the mean total pressure of the flow at the fan inlet, is in a range of 1.42 to 1.48 at cruise conditions;
• and
• a fan root to tip pressure ratio, defined as the ratio of the mean total pressure of the flow at the fan exit that subsequently flows through the engine core to the mean total pressure of the flow at the fan exit that subsequently flows through the bypass duct, is no greater than 0.95 at cruise conditions.