Tiltrotor aircraft control system

1. A flight control system for a tiltrotor aircraft, comprising:

a plurality of propulsion systems each independently tiltable between a vertical position and a horizontal position by aircraft effectors; and

a flight control computer configured to control the aircraft effectors in response to inputs from inceptors, the flight control computer comprising one or more processors and a memory, wherein the memory stores instructions for controlling aircraft effectors, the instructions causing the flight control computer to perform the steps of:

converting a signal representing longitudinal motion of a first inceptor into a fore-and-aft translational rate command for the tiltrotor aircraft;

converting the signal representing longitudinal motion of the first inceptor into an aircraft acceleration command when the longitudinal motion of the first inceptor has exceeded a threshold position and the tiltrotor aircraft has exceeded a threshold velocity;

converting a signal representing lateral motion of the first inceptor into a side-to-side translational rate command for the tiltrotor aircraft;

converting a signal representing longitudinal motion of a second inceptor into a height rate command for the tiltrotor aircraft; and

converting a signal representing lateral motion of the second inceptor to a yaw rate command for the tiltrotor aircraft.

2. The flight control system of claim 1 , wherein the threshold position is determined by a soft stop in the first inceptor.

3. The flight control system of claim 1 , wherein the instructions further causing the flight control computer to perform the steps of:

determining that the tiltrotor aircraft has transitioned out of a hover mode, wherein the propulsion systems have a generally vertical orientation in the hover mode; and

converting the signal representing a longitudinal motion of the second inceptor into a flight path change rate command for the tiltrotor aircraft.

4. The flight control system of claim 3 , wherein the instructions further causing the flight control computer to perform the steps of:

when the second inceptor is released, maintaining an aircraft flight path angle.

5. The flight control system of claim 1 , further comprising:

hard stops adapted to prevent lateral movement of the first inceptor beyond the threshold position.

6. The flight control system of claim 1 , wherein the threshold position varies depending on aircraft mode.

7. The flight control system of claim 1 , wherein the instructions further causing the flight control computer to perform the steps of:

when longitudinal motion of the first inceptor is held beyond the threshold position, transitioning aircraft propulsion systems from a hover mode to a cruise mode, wherein the propulsion systems have a generally vertical orientation in the hover mode and a generally horizontal orientation in the cruise mode.

8. A flight control system for a tiltrotor aircraft, comprising:

a plurality of propulsion systems each independently tiltable between a vertical position and a horizontal position by aircraft effectors; and

a flight control computer configured to control the aircraft effectors in response to inputs from inceptors, the flight control computer comprising one or more processors and a memory, wherein the memory stores instructions for controlling aircraft effectors, the instructions causing the flight control computer to perform the steps of:

converting a signal representing longitudinal motion of a first inceptor into a fore-and-aft translational rate command for the tiltrotor aircraft;

converting a signal representing lateral motion of the first inceptor into a side-to-side translational rate command for the tiltrotor aircraft;

converting a signal representing longitudinal motion of a second inceptor into a height rate command for the tiltrotor aircraft;

converting a signal representing lateral motion of the second inceptor to a yaw rate command for the tiltrotor aircraft; and

controlling a position of the tiltrotor aircraft using a Translational Rate Control (TRC) mode when an airspeed of the tiltrotor aircraft is below a threshold speed, and wherein, during the TRC mode when the first inceptor is released, decelerating the tiltrotor aircraft to zero speed and holding a constant ground position.

9. The flight control system of claim 1 , wherein the tiltrotor aircraft effectors are one or more of a rotor cyclic control, a rotor/propellor collective control, an electric motor speed, torque, or current command, a control surface, a rotor, a propellor, or an actuator configured to control the position of the propulsion system, control surface, rotor, or propellor.

10. The flight control system of claim 1 , further comprising:

a switch configured to command an automated transition to a minimum cruise speed when the tiltrotor aircraft is operating in a hover mode and to command an automated transition to a zero speed hover mode when the tiltrotor aircraft is operating in a cruise mode, wherein the propulsion systems have a generally vertical orientation in the hover mode and a generally horizontal orientation in the cruise mode.

11. An tiltrotor aircraft comprising:

a fuselage;

a cockpit within the fuselage, the cockpit including a first inceptor and a second inceptor;

a wing connected to the fuselage;

a first set of propulsion systems;

a second set of propulsion systems;

wherein each propulsion system includes a rotor assembly comprising a plurality of rotor blades, and wherein at least one of the first and second sets of propulsion systems are tiltable between a first position when the tiltrotor aircraft is in a hover mode and a second position when the tiltrotor aircraft is in a cruise mode; and

a flight control system configured to control the first and second sets of propulsion systems in response to inputs from the first and second inceptors, the flight control computer adapted to:

convert a signal representing longitudinal motion of the first inceptor into a fore-and-aft translational rate command for the tiltrotor aircraft;

convert a signal representing lateral motion of the first inceptor into a side-to-side translational rate command for the tiltrotor aircraft;

convert a signal representing longitudinal motion of the second inceptor into a height rate command for the tiltrotor aircraft; and

convert a signal representing lateral motion of the second inceptor to a yaw rate command for the tiltrotor aircraft;

wherein the flight control computer is further adapted to determine that the longitudinal motion of the first inceptor has exceeded a threshold position and that the tiltrotor aircraft has exceeded a threshold velocity, and to convert the signal representing longitudinal motion of the first inceptor beyond the threshold position into an acceleration command for the tiltrotor aircraft, wherein the threshold position is determined by a soft stop in the first inceptor.

12. The tiltrotor aircraft of claim 11 , further comprising:

a third set of propulsion systems, wherein the flight control system is further configured to control the third set of propulsion systems in response to inputs from the first and second inceptors; and wherein the propulsion systems collectively comprise a hexrotor configuration when the tiltrotor aircraft is in the hover mode.

13. The tiltrotor aircraft of claim 11 , wherein the flight control computer is further adapted to transition the propulsion systems from a hover mode to a cruise mode when the longitudinal motion of the first inceptor is held beyond the threshold position.

14. The tiltrotor aircraft of claim 11 , wherein the flight control computer is further adapted to determine that the tiltrotor aircraft has transitioned out of a hover mode, and to convert the signal representing a longitudinal motion of the second inceptor into a flight path change rate command for the tiltrotor aircraft.

15. The tiltrotor aircraft of claim 11 , wherein the flight control computer is further adapted to determine that an airspeed of the tiltrotor aircraft is below a threshold speed and to control a position of the tiltrotor aircraft using a Translational Rate Control (TRC) mode.