Abstract: A maneuver force gradient system causes a helicopter, that otherwise tends to pitch up in a banked turn, to pitch nose-down. A command signal (25) is provided as a function of the roll angle to operate the longitudinal trim actuator (27) which automatically moves the cyclic control (50) resiliently (28) forward to push the nose down. The pilot must consequently pull back on the cyclic control (50) to achieve a desired pitch attitude, thereby establishing a longitudinal positive maneuver-force gradient. The system is operable only when the pilot initiates a roll (33, 38, 50, 51) and the roll angle equals or exceeds 30.degree. (30, 33, 36, 37). Both analog (FIG. 1) and digital (FIG. 2) embodiments are disclosed, and the invention may be practiced in association with an AFCS (101) having the longitudinal trim actuator (27) and resilient linkage (28).

Abstract: An approach to hover control system for a helicopter in which a constant deceleration is commanded at an initial approach speed and then the actual deceleration as a time function of the airspeed from the initial airspeed to a second airspeed is measured. Based on these measures, the total deceleration time to approach to a hover condition can be predicted accurately after which the commanded deceleration is removed.

Abstract: An integrated aircraft longitudinal flight control system uses a generalized thrust and elevator command computation (38), which accepts flight path angle, longitudinal acceleration command signals, along with associated feedback signals, to form energy rate error (20) and energy rate distribution error (18) signals. The engine thrust command is developed (22) as a function of the energy rate distribution error and the elevator position command is developed (26) as a function of the energy distribution error. For any vertical flight path and speed mode the outerloop errors are normalized (30, 34) to produce flight path angle and longitudinal acceleration commands.The system provides decoupled flight path and speed control for all control modes previously provided by the longitudinal autopilot, autothrottle and flight management systems.

Abstract: An aircraft speed control system wherein the commanded lift floor (minimum lift) is increased in accordance with an anticipated decrease in headwind between headwind during final landing approach and that anticipated at touchdown. The system includes means for generating a signal which is a function of the difference between the headwind aloft and the headwind anticipated at touchdown. This signal, provided it indicates a decreased headwind at touchdown, is used to modify the programmed lift signal (which is in accordance with the angle of attack of the aircraft) to compensate the decreasing headwind condition, i.e. to increase the commanded lift floor.

Abstract: An improved PBA shutdown monitor circuit senses collective pitch control position rate of change magnitude and inhibits PBA shutdown in response to the continuous presence of sensed magnitude within a range of selected collective pitch rate magnitudes bounded by a slow rate limit signal value and a fast rate limit signal value.

Abstract: A cruise speed control apparatus in an aircraft performance management system wherein target Mach command is supplied to the engine automatic throttle controls to establish an engine thrust to overcome and equate to the aircraft nominal drag characteristics at that commanded Mach speed and simultaneously the difference between the actual Mach number speed and the target Mach command speed is supplied to the automatic pilot pitch axis control to cause the aircraft to maintain the commanded Mach speed through change in pitch attitude and altitude. The integral of any altitude standoff is used to adjust required thrust to achieve the commanded Mach target and reduce the standoff to zero. If necessary, filtered altitude error may be used to provide dynamic damping of the throttle control loop and compensation for long term degradation in the aircraft's drag characteristic with time is provided by measuring the drag degradation ratio and adjusting the target Mach command in accordance therewith.

Abstract: Speed control apparatus for use in an aircraft performance management system of the type wherein a target Mach number command is supplied to the aircraft pitch controls to attain the target Mach and is simultaneously supplied to the aircraft throttles to capture a computed engine pressure ratio (EPR) or fan speed (N.sub.1), said apparatus being operative during maximum thrust climbs and minimum thrust descents upon an abrupt step function target Mach number command wherein said step function command is converted to a ramp command, the slope of which is directly proportional to the existing thrust-minus-drag conditions of the aircraft and inversely proportional to its existing weight, thus ensuring a proper division between aircraft acceleration and rate of climb or aircraft deceleration and rate of descent.

Abstract: An aircraft vertical lift guidance signal is developed for providing optimum aircraft lift with limiting to avoid excessive acceleration and attitude. A lift computer produces an angle of attack signal as a function of aircraft altitude rate minus longitudinal acceleration such that demand increases in acceleration result in an increased angle of attack, thereby limiting acceleration. Attitude limiting is achieved by limiting the longitudinal signal to a constant value in response to aircraft acceleration exceeding a reference level.

Abstract: In an aircraft automatic flight control system having a reference parameter synchronizing system (70) operable in response to a trim release switch (44), an initial trim release period (139), on the order of a large fraction of a second (137) causes (217, 218) a relatively slow effect trim reference integrator (208, 211) time constant, for smooth transitions of any error signal, followed by a relatively fast (216) effective reference integrator time constant for close, rapid tracking of the reference signal with the actual aircraft parameter.

Abstract: An aircraft automatic of semiautomatic vertical path control system which coordinates operation of pitch and engine thrust control systems to transfer speed control from one system to the other depending on a requirement to climb, descend, or maintain altitude as determined by the polarity and magnitude of the difference between a selectable desired altitude and current actual altitude.

Abstract: An electrically controlled (16) mechanical actuator (13) is driven by optically generated (23) electrical power through an optically controlled (28) switch (26) in an electrically isolated module (20). Optical transducers (54, 62, 70) and feedback (29), as well as optical inputs (40, 89, etc.) to electrical signal processing equipment (46, 47, 49) in an electrically isolated module (22) dictate the electrical control (28). A helicopter flight control system is wholly digital, with solar remote power and optical intercommunication.

Abstract: An automatic aircraft pitch axis flight stabilization system which does not require the use of a gyroscope is described. Stability signals are derived from an altitude signal responsive to atmospheric pressure. Means responsive to rate of change of altitude produces a vertical rate signal and means responsive to rate of change of vertical rate produces a vertical acceleration signal. The vertical speed signal is combined with a command signal which causes the aircraft to fly at constant altitude, at constant vertical speed, or to descend along a glide slope, and the vertical acceleration signal to produce a control signal which operates a means, such as a servomechanism for positioning the vertical control surfaces of the aircraft.

Abstract: The invention concerns a process for the rapid detection of a wind gradie t.This process utilizes the relationship existing between the aerodynamic slope .gamma.a, the total slope .gamma..sub.T and the anemometric speed V, relation being able to be in the form ##EQU1## in which s is the Laplace operator, A is a value which is substantially constant or zero, in the case of a normal flight without disturbances, and which increases in the case of a wind gradient, wind forward becoming wind behind, the Vsel is an assigned value. This value A is mixed with a value representative of the capacity of the aircraft to overcome a wind gradient, so as to obtain a composite signal compared to a value of reference.The invention can be utilized at the moment of the phase of approach of an aircraft.

Abstract: A circuit for computing a signal representing the pitch attitude of an aircraft utilizes angle of attack based information and the output of a gyroscope to produce a calculated pitch signal which has a long term component dependent upon the angle of attack based information and a short term component dependent upon the gyroscope output signal. The calculated pitch signal may be used to pitch stabilize a head up display in the aircraft and in this event is modified with a correction signal derived from the pitch signal and the output of a head up display mounted accelerometer. Alternatively, the pitch signal may be combined with a signal representing the difference between the output of the display mounted accelerometer and the output of an angle of attack vane mounted accelerometer to provide a pitch stabilization signal which is free of turn and shear errors.

Abstract: In an automatic flight control system of the type having automatic stabilizer trim control, the long term, constant altitude cruise trim threshold limits which alter the maximum and minimum pull-in/drop-out deflection of the elevator relative to the stabilizer minimize the steady-state downward deflection of the elevator, thereby reducing unnecessary aerodynamic drag and realizing significant savings in fuel costs.

Abstract: An aircraft automatic or semiautomatic vertical path control system which coordinates operation of pitch and engine thrust control systems to transfer speed control from one system to the other depending on a requirement to climb, descend, or maintain altitude as determined by the polarity and magnitude of the difference between a selectable desired altitude and current actual altitude.

Abstract: An aircraft guidance system operable during both takeoff and go-around maneuvers allows safe operation even under adverse wind shear conditions. Initially the system controls vertical speed to achieve an acceptable, minimum climb rate regardless of airspeed loss. Should excess thrust exist such that the acceptable minimum climb rate is exceeded, increased vertical speed and airspeed are commanded. When the climb rate significantly exceeds the acceptable minimum, airspeed is controlled to a specified value. Should the aircraft ever approach the "stick shaker" condition, an override command limits aircraft angle of attack.

Abstract: A system for providing an optimum lift demand signal for aircraft maneuvers such as "go-around" includes a computer for generating a reference angle of attack signal which is functionally related to the aircraft's vertical velocity. The reference signal is compared with a signal corresponding to the aircraft's actual angle of attack, thereby producing an error signal. The error signal is utilized as a control to the aircraft's dynamics for optimizing the aircraft's climb-out performance.

Abstract: An automatic flight control system includes an automatic emergency descent mode initiated upon cabin decompression at high altitudes. Automatic safe capture of maximum descent rate and automatic flare to a safe altitude are provided, together with an automatic turn off the course existing at mode initiation.

Abstract: A process and system for the rapid detection of a wind gradient or change r an aircraft. Such a system provides for, on the one hand, the rapid detection of important or significant wind gradients or changes which can occur during the final phase of approach preceding the landing of the aircraft and, on the other hand, to inform the pilot or the automatic flight control system of the existence of this wind gradient sufficiently early to permit necessary corrective action to be taken.

Abstract: An aircraft pitch attitude stabilization system that utilizes an engine pressure ratio signal to cancel pitching moments due to changes in engine thrust. The changes in the engine pressure ratio signals which result from thrust changes are used to generate a pitch stabilization signal that is combined with other pitch control signals to automatically counteract pitching moments resulting from the changes in engine thrust.

Abstract: A pilot controlled stability control system that employs direct lift control (spoiler control) with elevator control to control the flight path angle of an aircraft. A computer on the aircraft generates an elevator control signal and a spoiler control signal, using a pilot-controlled pitch control signal and pitch rate, vertical velocity, roll angle, groundspeed, engine pressure ratio and vertical acceleration signals which are generated on the aircraft. The direct lift control by the aircraft spoilers improves the response of the aircraft flight path angle and provides short term flight path stabilization against environmental disturbances.

Abstract: Apparatus for providing an integrated display of flight instrument parameters on the screen of a single cathode ray tube is presented. The synthetically generated symbology provides the pilot with an integrated display of substantially all aircraft attitude and flight path command and control parameters including attitude and magnetic heading, barometric and radiometric attitude, vertical spread, critical take-off speeds, true airspeed and Mach airspeed, flight path angle, flight director path control commands, and mode annunciation for the flight director and automatic pilot systems.

Abstract: The outputs of a pair of linear accelerometers are utilized to provide measures of craft vertical acceleration and body axis pitch angular acceleration. The pitch angular acceleration signal is integrated to provide a measure of body axis pitch rate. The pitch rate signal is in turn integrated to provide a measure of body axis pitch attitude. An earth referenced pitch attitude sensor provides a measure of earth referenced pitch attitude and through a rate taker a measure of earth referenced pitch rate. The earth referenced sensor is utilized to calibrate out errors and effectively align the linear accelerometers so that in the event of a loss of the earth referenced sensor, the calibrated accelerometers have adequate accuracy to compute pitch rate and pitch attitude within the long period bandwidth needed to provide the stability augmentation function for a relaxed static stability aircraft.

Abstract: An automatic flight control apparatus for aircraft having the desired attitude of the aircraft in a balanced relation to the action speed of the aircraft and utilizing this reference signal to generate a difference signal which corresponds to the difference between the reference signal and a signal representing the actual attitude of the aircraft; this latter signal then is used as one of the control parameters. The difference signal is fed to a control system through a limiter having a limiting range to avoid feeding excessively large difference signals into the control system and thus preventing unstable flight.

Abstract: The longitudinal cyclic pitch channel of a helicopter has a negative pitch rate feedback bias added thereto when flying at higher speeds, thereby to stabilize the pitch axis against aft-load maneuvering instability and/or to induce a requirement for the pilot to provide a countermanding longitudinal cyclic pitch input through his cyclic pitch stick, the normal feed force of which provides an indication to him of the loading of the rotor as a consequence of undergoing pitch rate maneuvers.

Abstract: In order to provide a more accurate representation of aircraft pitch attitude for use in aircraft head up display devices, a circuit for generating a computed pitch signal responds to a longitudinal accelerometer and a vertical gyroscope within the aircraft wherein the computed pitch signal is generated by adding to the gyro pitch signal a correction factor computed by subtracting the value of the computed pitch signal from an inertial pitch signal derived from the longitudinal accelerometer. In order to compensate for the effects of aircraft acceleration on the longitudinal accelerometer signal, a computed acceleration signal derived from the difference between the longitudinal accelerometer signal and the gyro pitch signal is subtracted from the longitudinal accelerometer to generate the inertial pitch signal.

Abstract: An aircraft instrument comprising equipment for providing a first signal which is a function of airspeed and suitable for use in controlling an aircraft by variation of the airspeed to a predetermined value, an apparatus for providing a second signal which is a function of lift and suitable for use in controlling the aircraft by variation of the airspeed to adjust the lift to a predetermined value, and a selecting apparatus arranged to apply the second signal to a signal utilization mechanism for controlling the aircraft in accordance with said second signal except when said second signal falls below a predetermined datum level, which represents a safe margin above stall, whereupon the first signal is applied to the signal utilization mechanism, the selecting apparatus being arranged to provide a transition between control by the first signal and control by the second signal which is shorter than a transition between control by the second signal and control by the first signal.

Abstract: A flying method using total power, in particular for the take-off and overshoot of an aircraft, is disclosed in which the aerodynamic gradient .gamma.a is governed by reference to a desired gradient .gamma.d which is the total gradient .gamma.t modulated by the difference between the aircraft speed V and a reference speed V.sub.2. An error signal .delta. representative of the difference between the aerodynamic gradient .gamma.a and the desired gradient .gamma.d is displayed. The display of the desired gradient .gamma.d may be by means of the pitching tendency bar of an artificial horizon for example.

Abstract: A thin, high performance swept wing of the tapered type with an improved leading edge characterized by (1) camber that increases from a minimum near the wing root to a maximum near the wing tip, and (2) substantially a constant leading edge radius extending substantially across the wing span which defines a "blunt" contour. The wing in combination with a T-tail aircraft with a stick shaker/pusher activated by a rate of change of angle of attack sensor and optionally a strake between the leading edge and a wing tip tank which intrinsically combine to define a system that enhances aircraft performance by reducing minimum airspeed without impairing aircraft performance at high subsonic Mach (M) numbers.

Abstract: The instant invention relates to a system for estimating aircraft angle of attack .alpha. and sideslip angle .beta. from measured quantities such as angular body rate and linear acceleration. The estimated angle of attack and sideslip signals are generated by means of a Kalman filter configuration which simulates a model of the aircraft angle of attack and sideslip angle dynamics, and may be used either in an aircraft flight control network or for display purposes.

Abstract: A system for displaying to the pilot an indication to enable him to fly to a desired air speed and angle of attack, especially on takeoff. An artificial angle of attack error signal is generated from actual and desired air speeds and corrected by adding to it a differentiated pitch signal. The resultant calculated angle of attack error is displayed to the pilot unless flying to that indication would result in exceeding the actual maximum or minimum angle of attack limits, in which case an indication based on the actual exceeded limit is displayed.

Abstract: Flight path angle is displayed relative to the aircraft reference indicator in a unique display and aircraft control system particularly useful during approach operations. Flight path angle is computed as a function of vertical velocity of the aircraft and air speed. Angle of attack is displayed as an angle relative to the flight path angle and is derived by computing the difference between pitch and flight path angle. Thrust command is displayed vertically relative to the aircraft reference indicator while heading command is displayed laterally with respect to the aircraft reference indicator.

Abstract: The invention relates to a flight control system for an aircraft which maintains reliable control of the angle of attack (.alpha.) in those regions where rate of change of the lift coefficient (C.sub.L) as a function of .alpha. goes to zero or becomes negative. This may cause a condition in which the feedback loop for the pitch moment generating control surface can inadvertently drive the aircraft into a stall or other unstable mode. Reliable control of angle of attack is achieved through a network which produces an estimated angle of attack signal (.alpha.) from the measured pitch rate of the aircraft, the lift acceleration error signal, a gravity control signal and sideslip and roll information. The estimated angle of attack signal is processed in a network which produces a pseudo coefficient of lift signal C.sub.L. The pseudo lift coefficient signal is processed to produce a pseudo lift (or normal) acceleration signal, A.sub.Z, which is supplied to the aircraft control loop.

Abstract: A pair of electrostatic sensors are recessed in the outer wall of a superic ballistic body.The vertical electrostatic gradient in the atmosphere produces a voltage differential between the sensors when one sensor is higher than the other. Since the fixed geometrical relationship between the sensors is known, the magnitude and sign of the voltage differential can be correlated to the instantaneous attitude of the vehicle with respect to the earth's surface.

Abstract: A collimated head up display of pitch related information for an aircraft operator. A generated pitch signal combines a gyroscope signal referenced to the airframe with an inertial signal referenced to the head up display or combiner screen. A pitch error signal representing the difference between the generated pitch signal and the inertial pitch signal is limited and integrated to develop a pitch correction signal which is added to the gyroscope signal. Reference of the inertial signal to the combiner screen of the display eliminates static alignment errors. The pitch correction signal may be selected for display during alignment of the combiner screen.

Abstract: A controller for avoiding the pitching up of aircraft. A device is provided which, at a predetermined combination of the angle of attack and the aerodynamic rate of change of the angle of attack, supplied by a pitch rate gyro in connection with an electrical network, interrupts the pilot's command signal and transfers the control of the aircraft to the control device. The control device causes the aircraft to move through its change command by the pilot at primarily an optimum permissible limit for the angle of attack (.alpha.) and an optimum permissible limit for the aerodynamic rate of change for the rate of attack (.omega..sub.7 *). An optimum permissible limit which corresponds to the optimum permissible limit (.alpha. permissible) for the angle of attack (.alpha.) is also provided so that all control operations commanded by the pilot which would exceed .alpha. permissible are stopped prematurely.

Abstract: A control system for hydrofoil craft is one in which control surfaces are moved automatically in response to signals derived from the motion of the craft to stabilize and control the craft. In such systems, a potentially dangerous condition can occur in case of a failure or malfunction in the roll control system. In order to prevent such conditions, two roll sensing devices are provided which normally generate identical signals to actuate the control surfaces to stabilize the rolling motion. In case a failure or malfunction, the signals provided by the two sensing devices become different and apparatus is provided to compare these signals and to respond to a difference in the signals to initiate landing of the craft rapidly and safely.

Abstract: A flying method using total .[.power.]. .Iadd.energy.Iaddend., in particular for the take-off and overshoot of an aircraft, is disclosed in which the aerodynamic .[.gradient.]. .Iadd.flight path angle .Iaddend..gamma.a is governed by reference to a desired .[.gradient.]. .Iadd.flight path angle .Iaddend..gamma.d which is the .[.total gradient.]. .Iadd.potential flight path .Iaddend..gamma.t modulated by the difference between the aircraft speed V and a reference speed V.sub.2. An error signal .delta. representative of the difference between the aerodynamic .[.gradient.]. .Iadd.flight path angle .Iaddend..gamma.a and the desired .[.gradient.]. .Iadd.flight path angle .Iaddend..gamma.d is displayed. The display of the desired .[.gradient.]. .Iadd.flight path angle .Iaddend..gamma.d may be by means of the .[.pitching tendency bar of the artificial horizon.]. .Iadd.pitch command bar of an attitude director indicator .Iaddend.for example.