A FLADE aircraft gas turbine engine having an outer fan duct (3) circumscribing a preferably variable cycle inner gas turbine engine (10). A FLADE fan (2) is disposed in the outer fan duct (3) radially outward of and drivenly connected to a first fan (32) disposed in a first fan duct of the engine. The inlet of the first fan duct is sized to receive essentially the full mass airflow of the engine at full power conditions with the outer fan duct inlet (8) essentially closed off. The engine is further designed and operable to fully open the inlet of the outer fan duct (8) at predetermined part power flight conditions to avoid spillage drag and essentially close it at full power conditions such as take off. Another embodiment relates to a supersonic engine which operates the FLADE fan (2) fully open at supersonic cruise flight conditions and has an outer fan duct inlet (8) which is sized essentially sufficiently large enough to receive essentially only the engine inlet boundary layer flow and pass it though the outer fan duct (3) and not through the inner engine (10) where it would decrease the inner engine (10) efficiency. <IMAGE>
