Nose attitude control of a rotary wing aircraft

Abstract

An aircraft is provided including an airframe, an extending tail, and a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly. A translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe. The main rotor assembly and the translational thrust system are configured to provide hover nose down, hover nose up and hover level modes of flight.

What is claimed is: 
     
         1 . An aircraft comprising:
 an airframe;   an extending tail;   a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly; and   a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe;   wherein the main rotor assembly and the translational thrust system are configured to provide hover nose down, hover nose up and hover level modes of flight.   
     
     
         2 . The aircraft of  claim 1  wherein:
 in a hover nose down attitude the translational thrust system provides reverse thrust and in hover nose up attitude the translational thrust system provides forward thrust to counteract the main rotor assembly thrust vector. 
 
     
     
         3 . The aircraft of  claim 2  further comprising:
 a flight control system to independently control one or more of the main rotor assembly and the translational thrust system. 
 
     
     
         4 . The aircraft of  claim 3  further comprising:
 a plurality of sensors to detect sensor data of at least one environmental condition and at least one aircraft state data, the plurality of sensors providing the sensor data to the flight control system. 
 
     
     
         5 . The aircraft of  claim 4  wherein:
 in response to at least one control input commanding position hold, the flight control system is configured to analyze sensor data and command the translational thrust system and main rotor assembly to maintain current aircraft position, attitude, or a combination of position and attitude. 
 
     
     
         6 . The aircraft of  claim 4  wherein:
 in response to at least one control input commanding target visual tracking, the flight control system is configured to analyze the sensor data and command the translational thrust system and the main rotor assembly to adjust the aircraft in order to maintain pilot visibility of a target. 
 
     
     
         7 . The aircraft of  claim 4  wherein:
 in response to at least one control input commanding target line of fire tracking, the flight control system is configured to analyze the sensor data and command the translational thrust system and the main rotor assembly to adjust the aircraft in order to maintain weapon line of fire capability on target. 
 
     
     
         8 . An aircraft comprising:
 an airframe;   an extending tail;   a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly; and   a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe;   wherein the main rotor assembly and the translational thrust system are configured to provide for landing the aircraft substantially parallel to a non-horizontal ground surface.   
     
     
         9 . The aircraft of  claim 8  wherein:
 the main rotor assembly tilts the aircraft such that the aircraft is parallel to the non-horizontal ground surface and the translational thrust system provides sufficient thrust to maintain aircraft attitude. 
 
     
     
         10 . The aircraft of  claim 9  wherein:
 in a nose down attitude the translational thrust system provides reverse thrust and in a nose up attitude the translational thrust system provides forward thrust to counteract the main rotor assembly thrust vector. 
 
     
     
         11 . The aircraft of  claim 10  further comprising:
 a flight control system to independently control one or more of the main rotor assembly and the translational thrust system. 
 
     
     
         12 . The aircraft of  claim 11  further comprising:
 a plurality of sensors to detect sensor data of at least one environmental condition and at least one aircraft state data, the plurality of sensors providing the sensor data to the flight control system. 
 
     
     
         13 . The aircraft of  claim 12  wherein:
 in response to at least one control input commanding the aircraft to land, the flight control system is configured to analyze the sensor data, including terrain slope of a landing zone, and command the translational thrust system and the main rotor assembly to adjust the aircraft attitude so that it is substantially parallel to a non-horizontal ground surface. 
 
     
     
         14 . The aircraft of  claim 12  wherein:
 in response to at least one control input commanding the aircraft to land, the flight control system is configured to analyze the sensor data, including obstacles within a landing zone, and command the translational thrust system and the main rotor assembly to adjust the aircraft position to avoid the obstacles. 
 
     
     
         15 . A method of operating an aircraft, comprising:
 controlling the main rotor assembly to impart a hover nose down, hover nose up and hover level pitch moment on the aircraft; and   controlling the translational thrust system to counteract the main rotor assembly translational thrust vector and maintain a hover position.   
     
     
         16 . The method according to  claim 15  wherein:
 in a hover nose down attitude the translational thrust system provides reverse thrust and in hover nose up attitude the translational thrust system provides forward thrust to counteract the main rotor assembly thrust vector. 
 
     
     
         17 . The method according to  claim 16  wherein:
 the main rotor assembly and the translational thrust system are independently controlled by a flight control system. 
 
     
     
         18 . The method according to  claim 17  wherein:
 the aircraft contains a plurality of sensors to detect sensor data of at least one environmental condition and at least one aircraft state data, the plurality of sensors providing the sensor data to the flight control system. 
 
     
     
         19 . The method according to  claim 18  wherein:
 in response to at least one control input commanding position hold, the flight control system analyzes the sensor data and commands the translational thrust system and the main rotor assembly to maintain current aircraft position, attitude, or a combination of position and attitude. 
 
     
     
         20 . The method according to  claim 18  wherein:
 in response to at least one control input commanding target visual tracking, the flight control system analyzes the sensor data and commands the translational thrust system and the main rotor assembly to adjust the aircraft in order to maintain pilot visibility of a target. 
 
     
     
         21 . The method according to  claim 18  wherein:
 in response to at least one control input commanding target line of fire tracking, the flight control system analyzes the sensor data and commands the translational thrust system and the main rotor assembly to adjust the aircraft in order to maintain weapon line of fire capability on target. 
 
     
     
         22 . A method of operating an aircraft, comprising:
 controlling the main rotor assembly to impart a hover nose down, hover nose up and hover level pitch moment on the aircraft; and   controlling the translational thrust system to counteract the main rotor assembly translational thrust vector and enabling the aircraft to land substantially parallel to a non-horizontal ground surface.   
     
     
         23 . The method according to  claim 22  wherein:
 the main rotor assembly tilts the aircraft such that the aircraft is parallel to the non-horizontal ground surface and the translational thrust system provides sufficient thrust to maintain aircraft attitude. 
 
     
     
         24 . The method according to  claim 23  wherein:
 the main rotor assembly and the translational thrust system are independently controlled by a flight control system. 
 
     
     
         25 . The method according to  claim 24  wherein:
 the aircraft contains a plurality of sensors to detect sensor data of at least one environmental condition and at least one aircraft state data, the plurality of sensors providing the sensor data to the flight control system. 
 
     
     
         26 . The method according to  claim 25  wherein:
 in response to at least one control input commanding the aircraft to land, the flight control system analyzes the sensor data, including terrain slope of a landing zone, and commands the translational thrust system and the main rotor assembly to adjust the aircraft attitude so that it is substantially parallel to a non-horizontal ground surface. 
 
     
     
         27 . The method according to  claim 25  wherein:
 in response to at least one control input commanding the aircraft to land, the flight control system analyzes the sensor data, including obstacles within a landing zone, and command the translational thrust system and the main rotor assembly to adjust the aircraft position to avoid the obstacles.