A method of assembling a gas turbine assembly includes providing a core gas turbine engine including a high-pressure compressor, a combustor, and a turbine, coupling a low-pressure turbine axially aft from the core gas turbine engine, coupling a fan assembly axially forward from the core gas turbine engine, and coupling a booster compressor to the low-pressure turbine such that the booster compressor and the low-pressure turbine rotate at a first rotational speed.