Gas turbine engine with variable speed output

A method of operating a vertical takeoff and landing (VTOL) aircraft having an aircraft rotor operatively connected to a gas turbine engine that includes a low pressure compressor, a high pressure compressor, a high pressure turbine and a low pressure turbine, the method comprising:

• during a VTOL flight phase of the aircraft, driving the aircraft rotor at a high-power rotational speed, with the low pressure turbine rotating at a first rotational speed and the low pressure compressor rotating at a second rotational speed;
• and
• during a cruise flight phase of the aircraft, driving the aircraft rotor at a low-power rotational speed that is less than the high-power rotational speed by increasing the first rotational speed and decreasing the second rotational speed.

A gas turbine engine for a vertical takeoff and landing (VTOL) aircraft having an aircraft rotor, the gas turbine engine comprising:

• a low pressure turbine shaft connected to at least one turbine for driving the low pressure turbine shaft about an engine axis, and a low pressure compressor operatively connected to a low pressure compressor shaft independently rotatable relative to the low pressure the power turbine shaft;
• and
• means for operating the gas turbine engine in either a VTOL engine operating configuration or a cruise engine operating configuration, wherein in the VTOL engine operating configuration the low pressure turbine and the low pressure compressor are operated at their respective nominal design speed for takeoff, and in the cruise engine operating configuration, the low pressure turbine is allowed to rotate between 80% and 100% of its nominal design speed for takeoff and the low pressure compressor is driven to rotate at between 80% and 150% of its nominal design speed for takeoff.