US Patent 10054050 Low noise aeroengine inlet system

An aeroengine has an inlet system with a forward end with respect to a flight direction. The inlet system includes a main inlet duct for selectively directing a first air flow from a forward main intake opening of the main inlet duct to a compressor rotor, the forward main intake opening being defined at the forward end of the inlet system and a secondary inlet duct for directing a second air flow from a secondary intake opening of the secondary inlet duct to the compressor rotor only when the main inlet duct is closed. A control apparatus is provided for selecting the first and second air flow to enter into the compressor rotor.