A gas turbine engine comprises a fan, a core engine coupled to the fan, a fan case housing the fan and the core engine, a plurality of outlet guide vanes extending between the core engine and the fan case, a blade effective acoustic length (BEAL), and an acoustic spacing. The fan comprises a fan disk, a fan diameter, and a plurality of fan blades. The acoustic spacing comprises a distance between the fan and the plurality of outlet guide vanes, and in combination with the BEAL determines an acoustic spacing ratio of the gas turbine engine. The fan case comprises an inlet and an inlet length between the inlet and the fan, and in combination with the fan disk determines a disk spacing length and a disk-to-inlet length (DIL) ratio of the gas turbine engine.