Automatic pitch control system

Claim 2

In an automatic flight control system for an aircraft, apparatus for controlling the elevator of the aircraft and its associated tab in an automatic pitch maneuver, the apparatus comprising a trim actuator for positioning the tab responsive to an electrical driving signal, an elevator actuator for positioning the elevator responsive to an electrical driving signal, and a command signal source coupled to the actuators to provide the driving signals therefor, the command signal source forming a servoloop that drives the command signal toward a null condition prior to the execution of the automatic pitch maneuver and continually changes the command signal in one direction during the execution of the pitch maneuver, wherein the improvement is a trim bias source that produces a constant bias signal and means for combining the bias signal with the command signal applied to the trim actuator in a sense to cause the aircraft to pitch up so as to make the response of the aircraft to the command signal during the execution of the pitch maneuver unsymmetrical.

Claim 3

In an automatic flight control system for an aircraft, apparatus for executing an automatic pitch maneuver comprising: an elevator control surface on the aircraft; a tab control surface on the aircraft associated with the elevator control surface; an elevator actuator for positioning the elevator control surface responsive to an electrical input signal; a trim actuator for pOsitioning the tab control surface responsive to an electrical input signal; means for generating an electrical followup signal representative of the position of the elevator; a source of pitch command signals, the source forming part of a servoloop that drives the command signal toward a null condition prior to the execution of the automatic pitch maneuver and continually changes the command signal in one direction during the execution of the automatic pitch maneuver; means for combining the command signal and the followup signal to produce an elevator drive signal; means for applying the elevator drive signal to the input of the elevator actuator; a source of trim bias that produces a constant bias signal at its output; means for combining the command signal and the bias signal to produce a tab drive signal that is unsymmetrical as a function of changes in the command signal; and means for applying the unsymmetrical tab drive signal to the trim actuator in a sense to pitch the aircraft up.

Claim 4

In an automatic flight control system for an aircraft, apparatus for executing an automatic pitch maneuver comprising: an elevator control surface on the aircraft; a tab control surface on the aircraft associated with the elevator control surface; an elevator actuator for positioning the elevator control surface responsive to an electrical input signal; a trim actuator for pOsitioning the tab control surface responsive to an electrical input signal; means for generating an electrical followup signal representative of the position of the elevator; a source of pitch command signals, the source forming part of a servoloop that drives the command signal toward a null condition prior to the execution of the automatic pitch maneuver and continually changes the command signal in one direction during the execution of the automatic pitch maneuver; means for combining the command signal and the followup signal to produce an elevator drive signal; means for applying the elevator drive signal to the input of the elevator actuator; a source of trim bias that produces a constant bias signal at its output; means for combining the command signal and the bias signal to produce a tab drive signal that is unsymmetrical as a function of changes in the command signal; and means for applying the unsymmetrical tab drive signal to the trim actuator in a sense to pitch the aircraft up.

Claim 5

In an automatic flight control system for an aircraft, apparatus for controlling the pitch axis of the aircraft comprising: an elevator control surface on the aircraft; a tab control surface on the aircraft associated with the elevator control surface; an elevator actuator for positioning the elevator control surface responsive to an electrical input signal; a trim actuator for positioning the tab control surface responsive to an electrical input signal; means for generating an electrical followup signal representative of the position of the elevator; a first source of pitch command signals, for controlling the aircraft in an automatic pitch maneuver, the source forming part of a servoloop that drives the command signal toward a null condition prior to the execution of the automatic pitch maneuver and continually changes the command signal in one direction during the execution of the automatic pitch maneuver; a source of trim bias that produces a constant output signal; a first summing junction having first and second inputs and an output; means for coupling the followup signal generating means to the first input of the first summing junction; a second source of pitch command signal for controlling the aircraft in another automatic flight mode of operation; a mode selection switch for alternatively coupling the first and second sources to the second input of the first summing junction; a second summing junction having first and second inputs and an output; means for coupling the output of the first summing junction to the first input of the second summing junction; means for coupling the output of the second summing junction to the trim actuator; means for coupling the output of the first summing junction to the elevator actuator; and a switch for coupling the trim bias source to the second input of the second summing junction so as to bias the tab in a pitchup direction.

Claim 6

In an automatic flight control system for an aircraft, apparatus for controlling the pitch axis of the aircraft comprising: an elevator control surface on the aircraft; a tab control surface on the aircraft associated with the elevator control surface; an elevator actuator for positioning the elevator control surface responsive to an electrical input signal; a trim actuator for positioning the tab control surface responsive to an electrical input signal; means for generating an electrical followup signal representative of the position of the elevator; a first source of pitch command signals, for controlling the aircraft in an automatic pitch maneuver, the source forming part of a servoloop that drives the command signal toward a null condition prior to the execution of the automatic pitch maneuver and continually changes the command signal in one direction during the execution of the automatic pitch maneuver; a source of trim bias that produces a constant output signal; a first summing junction having first and second inputs and an output; means for coupling the followup signal generating means to the first input of the first summing junction; a second source of pitch command signal for controlling the aircraft in another automatic flight mode of operation; a mode selection switch for alternatively coupling the first and second sources to the second input of the first summing junction; a second summing junction having first and second inputs and an output; means for coupling the output of the first summing junction to the first input of the second summing junction; means for coupling the output of the second summing junction to the trim actuator; means for coupling the output of the first summing junction to the elevator actuator; and a switch for coupling the trim bias source to the second input of the second summing junction so as to bias the tab in a pitchup direction.