Variable geometry helicopter engine inlet

A helicopter, comprising:

• an airframe including a variable area engine inlet;
• at least one rotor, which is rotatable relative to the airframe to generate at least one of lift and thrust;
• an engine disposed within an interior of the airframe, wherein the engine is receptive of air drawn into the interior through the variable area engine inlet and is coupled to the at least one rotor to drive rotation of the rotor in accordance with a combustion of a mixture of fuel and the air,
• a capture area of the variable area engine inlet wherein the variable area engine inlet is variable in accordance with current conditions, and wherein the variable area engine inlet is defined by a fuselage section, a leading side of a horizontally oriented top wall section disposed to oppositely face the fuselage section at a distance, a main rotor pylon section and a leading side of a vertically oriented side wall section disposed to oppositely face the main rotor pylon section at a distance such that a forward-most portion of the capture area is a forward facing opening through which airflow is drawn,
• at least one of the horizontally oriented top wall section and the vertically oriented side walls section comprising a movable portion that is movable in a height-wise direction and a width-wise direction, respectively, to vary the capture area;
• and
• a controller configured to constrict the capture area of the variable area engine inlet in accordance with high-speed flight conditions and to dilate the capture area in accordance with low-speed or hover flight conditions, wherein the variable area engine inlet comprises first and second variable area engine inlets and the controller is configured to independently vary respective capture areas of the first and second variable area engine inlets in accordance with the current conditions and asymmetric flows relative to the first and second variable area engine inlets.

A method of controlling first and second variable area engine inlets of a helicopter, the method comprising:

• determining whether a current flight condition is a hover or low-speed flight condition or a high-speed flight condition;
• orienting a capture area, which is defined by a fuselage section, a leading side of a horizontally oriented top wall section disposed to oppositely face the fuselage section at a distance, a main rotor pylon section and a leading side of a vertically oriented side wall section disposed to oppositely face the main rotor pylon section at a distance, of each of the first and second variable area engine inlets such that a forward-most portion of the capture area is a forward facing opening through which airflow is drawn;
• constricting the capture area in an event a result of the determining indicates that the current flight condition is the high-speed flight condition;
• and
• dilating the capture area in an event the result of the determining indicates that the current flight condition is the hover or low-speed flight condition,
• wherein the constricting and the dilating comprises at least one of:
• moving the horizontally oriented top wall section in a height-wise direction relative to the fuselage section;
• moving the vertically oriented side wall section in a width-wise direction relative to the main rotor pylon section and
• independently varying respective capture areas of the first and second variable area engine inlets in response to asymmetric flow conditions relative to the first and second variable area engine inlets.