Approach to hover control system for helicopters
First Claim
1. Apparatus for generating flight path control signals for an aircraft having a pitch attitude control system including rotor cyclic pitch command means for controlling the pitch attitude and rotor collective pitch command means for controlling the vertical lift thereof,means for providing a first signal representative of a vertical velocity of said aircraft with respect to a predetermined longitudinal flight path,means for providing a second signal representative of a velocity error corresponding to a difference in actual flight path from said predetermined flight path,means for combining said first and second signals to form a difference thereof, andfunction means proportional to an angular measure of said predetermined flight path, said angular measure relating vertical velocity to longitudinal velocity, said function means responsive to said difference signal, whereby to derive a longitudinal velocity signal corresponding to the vertical velocity of said aircraft with respect to said actual flight path.
1 Assignment
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Accused Products
Abstract
An improved apparatus for automatic deceleration of a helicopter to substantially zero air speed from a glide slope descent. Parameters available in a typical helicopter automatic flight control system, such as vertical speed, glide slope error, longitudinal acceleration, and pitch attitude are blended together in a manner as to approximate helicopter ground speed which is then used in a control law computation to decelerate the helicopter to a near hover speed as the vehicle approaches a preset altitude minimum.
42 Citations
9 Claims
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1. Apparatus for generating flight path control signals for an aircraft having a pitch attitude control system including rotor cyclic pitch command means for controlling the pitch attitude and rotor collective pitch command means for controlling the vertical lift thereof,
means for providing a first signal representative of a vertical velocity of said aircraft with respect to a predetermined longitudinal flight path, means for providing a second signal representative of a velocity error corresponding to a difference in actual flight path from said predetermined flight path, means for combining said first and second signals to form a difference thereof, and function means proportional to an angular measure of said predetermined flight path, said angular measure relating vertical velocity to longitudinal velocity, said function means responsive to said difference signal, whereby to derive a longitudinal velocity signal corresponding to the vertical velocity of said aircraft with respect to said actual flight path.
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9. Apparatus for controlling the flight of a helicopter along a descent path to a hover or landing termination point, comprising:
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means for providing a signal representative of a desired air speed during the initial point of the descent at an altitude greater than a predetermined altitude from said termination point, means responsive to a function of altitude rate, glide slope error rate, longitudinal acceleration, and pitch attitude for providing a signal representative of the actual ground speed of the helicopter, means for providing a ground speed reference signal variable in accordance with altitude from an initial value at least equal to the maximum desired air speed at an altitude greater than said predetermined altitude to a final value representative of a predetermined lower ground speed, means for varying said reference signal from said initial to said final value as the helicopter proceeds along the descent path, commencing at said predetermined altitude from said termination point, means responsive to said actual ground speed signal and said variable reference signal for selectively providing an output indicative of craft attitude required to reduce the actual ground speed to said predetermined lower ground speed substantially at said termination point, means responsive to a predetermined function of acceleration and pitch attitude for selectively providing a further output indicative of craft attitude required to reduce the actual ground speed to a further predetermined ground speed in accordance with a predetermined flare path of descent substantially at said termination point, and means for selecting said output or said further output representative of engaging a desired descent path.
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Specification