US 4,980,835 A · Control law system for X-Wing aircraft

Abstract

Control law system for the collective axis, as well as pitch and roll axes, of an X-Wing aircraft and for the pneumatic valving controlling circulation control blowing for the rotor. As to the collective axis, the system gives the pilot single-lever direct lift control and insures that maximum cyclic blowing control power is available in transition. Angle-of-attach de-coupling is provided in rotary wing flight, and mechanical collective is used to augment pneumatic roll control when appropriate. Automatic gain variations with airspeed and rotor speed are provided, so a unitary set of control laws works in all three X-Wing flight modes. As to pitch and roll axes, the system produces essentially the same aircraft response regardless of flight mode or condition. Undesirable cross-couplings are compensated for in a manner unnoticeable to the pilot without requiring pilot action, as flight mode or condition is changed. A hub moment feedback scheme is implemented, utilizing a P+I controller, significantly improving bandwidth. Limits protect aircraft structure from inadvertent damage. As to pneumatic valving, the system automatically provides the pressure required at each valve azimuth location, as dictated by collective, cyclic and higher harmonic blowing commands. Variations in the required control phase angle are automatically introduced, and variations in plenum pressure are compensated for. The required switching for leading, trailing and dual edge blowing is automated, using a simple table look-up procedure. Non-linearities due to valve characteristics of circulation control lift are linearized by map look-ups.

Claims39

Dependent claims

A method of controlling an X-Wing type aircraft made up of at least one set of control laws, which aircraft has a rotary wing ("RW") mode and a stopped rotor ("SR") mode with a conversion ("CV") mode as the rotor changes between said RW and SR modes during flight of the aircraft, with the rotor having a collective pressure ratio set point and a reduced lift state and with the aircraft having a controlled aircraft response during flight under a control law system, comprising the following steps:

(a) utilizing a pneumatic collective control law commanding pneumatic collective as a function of rotor speed, and, in said RW mode, making the collective pressure ratio set point a positive value, decreasing but remaining positive in said SR mode, and, during said rotor mode conversion ("CV"), compensating for the reduced lift state by an increase in collective blowing;
(b) utilizing a set of pitch and roll axes control laws to essentially producing said aircraft response regardless of flight mode or flight condition by compensating for undesirable cross-couplings without requiring pilot action, as said flight mode or said condition is changed;
implementing a hub moment feedback scheme utilizing a proportional and integral ("P+I") controller, significantly improving its bandwidth;
and providing limits to the rotor hub movements protecting the aircraft structure from inadvertent damage;
and
(c) utilizing a set of pneumatic valving control laws for controlling the position of the valves for the blowing out of air at the blade edges of the rotor and providing the pressure required at each valve azimuth location, with automated switching for leading edge blowing ("LEB"), trailing edge blowing ("TEB") and dual edge blowing ("DEB") using a table look-up procedure.

3 more elements

A control system for an X-Wing aircraft made up of at least one set of control laws, which aircraft has a rotary wing ("RW") mode and a stopped rotor ("SR") mode with a conversion ("CV") mode as the rotor changes between said RW and SR modes during flight of the aircraft, with the rotor having a collective pressure ratio set point and a reduced lift state and with the aircraft having a controlled aircraft response during flight under the control law system, comprising:

mechanical collective control law signal generating means for providing signals giving the pilot single-lever direct lift control, while making available at least substantial cyclic blowing control power during said conversion;
for providing signals for angle-of-track de-coupling in rotary wing flight, and for using mechanical collective to augment pneumatic roll control;
and for providing signals for automatic gain variations with airspeed and rotor speed, resulting in a unitary set of control laws working in the rotor wing ("RW"), conversion ("CV") and stopped rotor ("SR") modes of the aircraft;
pneumatic collective control law signal generating means associated with said mechanical collective control law signal generating means for generating signals commanding the pneumatic collective as a function of said rotor speed, and, in said RW mode, for making the collective pressure ratio set point a positive value, decreasing but remaining positive in said SR mode, and, during said conversion, for compensating the reduced lift state by an increase in collective blowing;
pitch and roll axes control laws signal generating means associated with said mechanical collective control law signal generating means and said pneumatic collective control law signal generating means for generating signals for essentially producing said aircraft response regardless of flight mode or flight condition by compensating for any undesirable cross-couplings without requiring pilot action, as said flight mode or said flight condition is changed;
for implementing a hub moment feedback scheme utilizing a proportional and integral ("P+I") controller, significantly improving its bandwidth;
and for providing limits to the rotor hub movements protecting the aircraft structure from inadvertent damage;
and
pneumatic valving control laws signal generating means associated with said mechanical collective control law signal generating means and said pneumatic collective control law signal generating means for generating signals for controlling the position of the valves for the lowing out of air at the blade edges of the rotor and for providing the pressure required at each valve azimuth location, with automated switching for leading edge blowing ("LEB"), trailing edge blowing ("TEB") and dual edge blowing ("DEB") using a table look-up procedure.

6 more elements

Dependencies are inferred from the claim text.

Control law system for X-Wing aircraft

Life of this patent

Control law system for X-Wing aircraft

Life of this patent

Abstract

Claims39