Independent speed and attitude control for a rotary wing aircraft
One aspect is a flight control system for independent speed and attitude control of a rotary wing aircraft that includes a main rotor system and a translational thrust system. The flight control system includes a flight control computer configured to interface with the main rotor system and the translational thrust system. The flight control computer includes processing circuitry configured to execute control logic. A pitch attitude reference generator provides a pitch attitude reference to a main rotor controller to command the main rotor system based on pilot input. A longitudinal reference generator produces a longitudinal reference as a longitudinal position or longitudinal velocity based on pilot input. An attitude-to-propulsor crossfeed converts the pitch attitude reference into a propulsor trim adjustment. A propeller pitch controller combines the longitudinal reference and the propulsor trim adjustment into a propeller command, and provides the propeller command to the translational thrust system.
1. A flight control system for independent speed and attitude control of a rotary wing aircraft comprising a main rotor system and a translational thrust system, the flight control system comprising:
a flight control computer configured to interface with the main rotor system and the translational thrust system, the flight control computer comprising processing circuitry configured to execute control logic comprising:
a pitch attitude reference generator configured to generate a pitch attitude reference and provide the pitch attitude reference to a main rotor controller in response to a first pilot input to command the main rotor system;
a longitudinal reference generator configured to produce a longitudinal reference as a longitudinal position or longitudinal velocity based on a second pilot input;
an attitude-to-propulsor crossfeed configured to convert the pitch attitude reference into a propulsor trim adjustment; and
a propeller pitch controller configured to combine the longitudinal reference and the propulsor trim adjustment into a propeller command, and provide the propeller command to the translational thrust system.
2. The flight control system according to claim 1 , further comprising:
reference prioritization logic configured to prioritize one of the pitch attitude reference or the longitudinal reference in order to accommodate a limited control envelope.
3. The flight control system according to any of claims 1 - 2 , wherein the flight control computer is configurable to disable the attitude-to-propulsor crossfeed and revert to a pitch attitude-based speed control mode.
4. The flight control system according to claim 1 , further comprising:
an altitude reference generator configured to produce an altitude based pitch reference for the pitch attitude reference generator.
5. The flight control system according to claim 1 , wherein the flight control computer is further configured to interface with a plurality of sensors and provide feedback signals to the main rotor controller and the translational thrust system based on the sensors.
6. The flight control system according to claim 1 , wherein the attitude-to-propulsor crossfeed maps aircraft pitch angles to propeller pitch angles.
7. The flight control system according to claim 1 , wherein the main rotor system further comprises dual contra-rotating main rotors.
8. The flight control system according to claim 1 , wherein the translational thrust system comprises an auxiliary propulsor configured as a pusher propeller.
9. A method of providing independent speed and attitude control on a rotary wing aircraft comprising a main rotor system and a translational thrust system, the method comprising:
generating a pitch attitude reference and providing the pitch attitude reference to a main rotor controller in response to a first pilot input to command the main rotor system;
producing a longitudinal reference as a longitudinal position or longitudinal velocity based on a second pilot input;
converting the pitch attitude reference into a propulsor trim adjustment;
combining the longitudinal reference and the propulsor trim adjustment into a propeller command; and
providing the propeller command to the translational thrust system.
10. The method according to claim 9 , further comprising:
prioritizing one of the pitch attitude reference or the longitudinal reference in order to accommodate a limited control envelope.
11. The method according to claim 9 , further comprising:
disabling an attitude-to-propulsor crossfeed to revert to pitch attitude-based speed control mode.
12. The method according to claim 9 , further comprising:
producing an altitude based pitch reference for a pitch attitude reference generator.
13. The method according to claim 9 , wherein converting the pitch attitude reference into a propulsor trim adjustment further comprises mapping aircraft pitch angles to propeller pitch angles.
14. The method according to claim 9 , wherein the main rotor system further comprises dual contra-rotating main rotors.
15. The method according to claim 9 , wherein the translational thrust system comprises an auxiliary propulsor configured as a pusher propeller.