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A method of stabilizing a jet-powered tri-mode aircraft as the aircraft travels in a helicopter mode, a compound mode, and a fixed-wing mode is disclosed. The method includes receiving a plurality of velocity vector component values and velocity vector commands derived from either (1) a number of pi

A method of stabilizing a jet-powered tri-mode aircraft as the aircraft travels in a helicopter mode, a compound mode, and a fixed-wing mode is disclosed. The method includes receiving a plurality of velocity vector component values and velocity vector commands derived from either (1) a number of pilot operated controllers or (2) a commanded array of waypoints, which are used for fully automated flights, and a rotor speed reference value, which is decreased with increasing forward speed to unload the rotor, thereby permitting conditions for stopping the rotor in flight. Stabilization of the commanded velocity vector is achieved in all modes of flight using blended combinations of rotor swashplate controls and aerodynamic controls such as elevons, canards, rudders, and a horizontal tail. Stabilization to the commanded velocity vector includes a plurality of control constraints applied to the pilot stick controllers that prevent penetration of envelope limits.

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1. A jet-powered tri-mode aircraft capable of automatically transitioning from a helicopter mode to a compound mode to a fixed-wing mode without any intervention by a pilot of the aircraft, the aircraft comprising:a fuselage; a turbofan engine mounted within the fuselage for producing an exhaust gas

1. A jet-powered tri-mode aircraft capable of automatically transitioning from a helicopter mode to a compound mode to a fixed-wing mode without any intervention by a pilot of the aircraft, the aircraft comprising:a fuselage; a turbofan engine mounted within the fuselage for producing an exhaust gas flow; a rotor blade having a plurality of exit nozzles for outputting the gas flow, the rotor blade being mounted on the fuselage; a mast valve for regulating the gas flow to the plurality of exit nozzles of the rotor blade; a cruise nozzle for regulating and outputting the gas flow; and a scheduler for scheduling the mast valve and the cruise nozzle as a function of aircraft speed and for monitoring the gas flow being output from the plurality of exit nozzles, the mast valve, and the cruise nozzle to prevent the turbofan engine from stalling. 2. The aircraft according to claim 1, further comprising an engine stall controller for receiving a command from the scheduler if the plurality of exit nozzles and the cruise nozzle are unable to output enough gas flow to prevent the turbofan engine from stalling and for modulating an exit area based on the command to achieve a desired engine stall margin.3. The aircraft according to claim 2, wherein the exit area is a plurality of lateral thrusters including a first lateral thruster positioned on a left side of the fuselage and a second lateral thruster positioned on a right side of the fuselage.4. The aircraft according to claim 1, wherein the scheduler schedules the mast valve and the cruise nozzle to provide a smooth transition from the helicopter mode to the compound mode to the fixed-wing mode.5. The aircraft according to claim 1, further comprising a canard wing attached to a front end of the fuselage and a horizontal tail having a plurality of elevons and being attached to a rear end of the fuselage, the canard wing and the horizontal tail are configured to provide control of the aircraft.6. The aircraft according to claim 5, further comprising a control stick for controlling the rotor blade, the canard wing, the horizontal tail, rudders, lateral thrusters, and the plurality of elevons to maintain a stable flight path during the helicopter mode, the compound mode, and the fixed-wing mode.7. The aircraft according to claim 6, wherein the control stick is a 3-axis controller and a single axis vertical controller or a 4-axis controller.8. The aircraft according to claim 6, wherein the control stick provides control of the aircraft and maintains a stable flight path during the helicopter mode, the compound mode, and the fixed-wing mode without having a separate throttle lever and a separate collective control.9. The aircraft according to claim 6, further comprising a velocity vector control system for maintaining a commanded velocity vector that is controlled by the rotor blade, the canard wing, the horizontal tail, the rudders, the lateral thrusters, and the plurality of elevons to maintain a stable flight path during the helicopter mode, the compound mode, and the fixed-wing mode.10. The aircraft according to claim 9, wherein the commanded velocity vector is controlled to achieve the stable flight path.11. The aircraft according to claim 9, wherein the commanded velocity vector is derived using acceleration commands received from the control stick that is used to manually control the aircraft in the helicopter mode, the compound mode, and the fixed-wing mode.12. The aircraft according to claim 1, further comprising a velocity vector control system, coupled to the turbofan engine, for receiving a plurality of acceleration commands and a yaw axis rotation command and for generating a velocity vector command using the plurality of acceleration commands.13. The aircraft according to claim 12, wherein the velocity vector command inherently prevents the aircraft from traveling beyond an envelope limit pertaining to acceleration or velocity.14. The aircraft according to claim 12, wherein the velocity vector command, which is used to attain a reference flight path, is reduced automatically in proportion to the aircraft's approach to an envelope limit pertaining to acceleration or velocity.15. The aircraft according to claim 12, wherein the velocity vector control system controls a plurality of control stick gradients if the aircraft approaches an envelope limit pertaining to acceleration or velocity.16. The aircraft according to claim 12, wherein the plurality of acceleration commands and the yaw axis rotation command are received from a control stick that produces control stick commands.17. The aircraft according to claim 16, wherein the velocity vector control system generates control gradients based on the aircraft's response to changes in the control stick commands and adjusts the control stick commands based on the control gradients to prevent the aircraft from traveling beyond the envelope limit pertaining to acceleration or velocity.18. A method for scheduling canard positions and horizontal tail positions of a jet-powered tri-mode aircraft as a function of the speed of the aircraft to achieve smooth unloading of a rotor blade of the aircraft, the method comprising:providing closed loop control of the pitch attitude using a pitch moment command having a low frequency component and a high frequency component; providing open loop control of the horizontal tail position using the pitch moment command; determining the horizontal tail position relative to its position limit; and if the horizontal tail position is not approaching its position limit, then scheduling the elevon position using the high frequency component and scheduling the horizontal tail position using the sum of the open loop control and the low frequency component; if the horizontal tail position is approaching its position limit, then scheduling the elevon position using a large portion of the low frequency component and the high frequency component and scheduling the horizontal tail position using a small portion of the low frequency component; and if the horizontal tail position has reached its position limit, then scheduling the elevon position using the pitch moment command and scheduling the horizontal tail position to be fixed at its position limit. 19. The method according to claim 18, further comprising providing closed loop control of the pitch and roll attitude and directional controls and vertical acceleration controls using swashplate controls and blended elevon control for pitch and roll attitude blended differential lateral thrusters, and rudder control for aircraft yaw.20. The method according to claim 19, wherein the swashplate controls include lateral and longitudinal cyclic and collective controls.21. The method according to claim 18, wherein determining the horizontal tail position relative to its position limit includes sensing the position of the horizontal tail.22. A method for scheduling, as a function of aircraft speed, the transition from a helicopter mode to a compound mode to a fixed-wing mode of a jet-powered tri-mode aircraft having a rotor blade, a mast valve, a cruise nozzle, a canard wing, and a horizontal tail, the method comprising:scheduling a rotor speed reference as a function of aircraft speed; scheduling the mast valve to open and the cruise nozzle to close in the helicopter mode; scheduling the mast valve to gradually close and the cruise nozzle to gradually open in the compound mode; and scheduling the mast valve to close, the cruise nozzle to open, and the tilt of the canard wing to gradually decrease in the fixed-wing mode. 23. The method according to claim 22, wherein the rotor speed reference is gradually reduced to about seventy percent at the conversion speed of the aircraft.24. The method according to claim 22, further comprising modifying the schedule for the mast valve and the schedule for the cruise nozzle to improve the range of control for the rotor speed control or the forward speed control in the compound mode.25. The method according to claim 22, further comprising determining an actual engine stall margin value from a fan pressure ratio and an engine mass flow.26. The method according to claim 25, further comprising comparing the actual engine stall margin value to a desired stall margin value and scheduling the lateral thrusters to open if the actual engine stall margin is less than the desired stall margin, and scheduling the lateral thrusters to close if the actual engine stall margin is greater than the desired stall margin.27. The method according to claim 26, further comprising increasing the desired stall margin value to avoid operating the engine in a condition that is vulnerable to power transients if an exhaust gas temperature is greater than a maximum desired value.28. The method according to claim 22, further comprising scheduling closed loop control of the horizontal tail surface and elevons to minimize the need for swashplate controls thereby minimizing the flapping of the rotor blade.29. A method for performing an automatic autorotation of a rotor blade of a jet-powered tri-mode aircraft in the event of an engine failure, the method comprising:setting a horizontal speed reference for the aircraft using modulation of pitch attitude; maintaining the rotor speed using collective position modulation; computing a flare altitude using an acceptable vertical acceleration; and setting a terminal vertical speed reference for the aircraft using the acceptable vertical acceleration. 30. The method according to claim 29, wherein the horizontal speed reference is set to about 60 knots.31. The method according to claim 29, further comprising determining the acceptable vertical acceleration for a final rate of descent flare by increasing or decreasing the need for collective position modulation.32. The method according to claim 31, further comprising inputting a forward deceleration command into a forward speed control loop to decrease the horizontal speed reference to approximately 0 when the altitude of the aircraft reaches 0.33. The method according to claim 32, wherein the step of inputting the acceptable vertical acceleration into the vertical speed control loop is performed simultaneously with the step of inputting the forward deceleration command into the forward speed control loop to decrease the horizontal speed reference.34. The method according to claim 29, wherein the vertical speed reference is set to about ?1.0 feet per second.35. The method according to claim 29, further comprising increasing the angle of attack of the aircraft as a result of the forward deceleration, thereby decreasing the rotor drag torque associated with the increased collective used for the vertical flare, thereby minimizing the decay in the vertical speed during the final flare.36. The method according to claim 29, further comprising estimating the altitude of the aircraft above the ground using an inertial/GPS device and a radar device where the radar device becomes dominant when the altitude is below about 10 feet.37. The method according to claim 36, wherein the radar device includes a filter for providing variable time constant inertial smoothing to accommodate for rough surface and radar altimeter noise.38. The method according to claim 29, further comprising measuring a plurality of aircraft states and computing a plurality of predicted aircraft states as a function of aircraft maneuvers.39. The method according to claim 38, wherein the plurality of aircraft states are selected from a group consisting of the horizontal speed reference of the aircraft, the vertical speed reference of the aircraft, and an altitude of the aircraft.40. A method for stabilizing a jet-powered tri-mode aircraft as the jet-powered tri-mode aircraft travels in a compound mode, which is between a helicopter mode and a fixed-wing mode, the method comprising:receiving a plurality of velocity vector component values, a plurality of velocity vector commands, and a rotor speed reference value; generating a pitch attitude command and a roll attitude command using the plurality of velocity vector component values, the plurality of velocity vector commands, and the rotor speed reference value; generating a plurality of acceleration commands using the pitch attitude command and the roll attitude command and a plurality of vertical acceleration commands using a commanded array of waypoints or pilot control stick commands; and scheduling the rotor blade speed, a canard of the aircraft, and a horizontal tail of the aircraft as a function of a forward speed of the aircraft. 41. The method according to claim 40, wherein the plurality of velocity vector component values and velocity vector commands are derived from a plurality of pilot operated controllers.42. The method according to claim 40, wherein the commanded array of waypoints are used for fully automated flights.43. The method according to claim 40, wherein the plurality of velocity vector component values and velocity vector commands are derived from the commanded array of waypoints.44. The method according to claim 40, wherein the rotor speed reference value is determined by the requirement that the aircraft lift be gradually transferred from the rotor blade to the aerodynamic surfaces.45. A method for controlling the vertical flight path of a jet-powered tri-mode aircraft having a rotor blade, a mast valve, and a cruise nozzle as the jet-powered tri-mode aircraft travels in a compound mode, which is between a helicopter mode and a fixed-wing mode, the method comprising:generating a throttle command to control the forward speed of the aircraft; generating a collective command to control the rotor speed of the rotor blade; and generating pitch attitude and angle of attack commands to control the vertical flight path of the aircraft. 46. The method according to claim 45, wherein the throttle command, the collective command, and the pitch attitude command are integrated to provide a stable flight for the aircraft.47. The method according to claim 45, wherein the collective command is generated via the rotor swashplate controls.48. The method according to claim 45, wherein the coupling between rotor speed control, forward speed control and vertical flight path control is stabilized with frequency shaping compensators in the throttle control loop to maintain an optimum control bandwidth in these three interacting controls.49. The method according to claim 45, further comprising modifying the mast valve position and the cruise nozzle position based on the throttle command, the collective command, the pitch attitude command, and the angle of attack command to provide an increased range of rotor speed control authority and hence an expanded aircraft flight envelope.