Geared turbofan engine gearbox arrangement

A gas turbine engine comprising:

• a fan section including a fan having a plurality of fan blades that deliver airflow to a bypass duct, the plurality of fan blades each having leading edge, a trailing edge, a peak tip radius Rt defined at the leading edge and an inboard leading edge radius Rh defined at a first inboard boundary of a first flowpath at the leading edge, and a ratio of Rh to Rt being less than 0.4;
• a core engine defining a core flowpath and a longitudinal axis, the core engine including a first turbine that drives a first compressor, a second compressor, and a fan drive turbine that drives the fan section and arranged aft of the first turbine;
• wherein a second inboard boundary of the core flowpath has a radius R1 defined at a first stage of the second compressor and a radius R2 defined at a splitter rim, each radius R1, R2 defined relative to the longitudinal axis, the splitter rim guides flow into the core flowpath, and a ratio of R1 to R2 is greater than 0.5;
• wherein the tan section has only a single fan stage comprising the fan;
• and
• wherein a ratio of an axial length L10 between the radii R1, R2 to the radius R2 is less than 1.2.

A method of designing a gas turbine engine comprising:

• providing a fan section including a fan having a plurality of fan blades that deliver airflow to a bypass duct, the fan blades each having a leading edge, a trailing edge, a peak tip radius Rt defined at the leading edge and an inboard leading edge radius Rh defined at a first inboard boundary of a first flowpath at the leading edge, and a ratio of Rh to Rt being less than 0.4;
• and
• providing a core engine including a first turbine that drives a first compressor, a second compressor, and a fan drive turbine that drives the fan section, the fan drive turbine including 5 stages, the first compressor including a greater number of stages than the fan drive turbine, and the second compressor including a greater number of stages than the first turbine;
• wherein the fan section has only a single fan stage comprising the fan;
• wherein the core engine defines a core flowpath and a longitudinal axis;
• wherein a second inboard boundary of the core flowpath has a radius R1 defined at a first stage of the second compressor and has a radius R2 defined at a splitter rim, each radius R1, R2 defined relative to the longitudinal axis, the splitter rim guides flow into the core flowpath;
• and
• wherein a ratio of an axial length L10 between the radii R1, R2 to the radius R2 is less than 1.2.