Abstract: Method and apparatus for commanding an optimal flight path for an aircraft encountering a windshear condition. An airspeed rate signal equal in magnitude and opposite in sense to the windshear is applied to derive a variable rate of change of airspeed command for application to a flight director indicator. Limits are placed on the derived command such that the minimum allowable speed command is stick shaker speed and the maximum allowable speed command is the nominal speed in the absence of the windshear. The resultant command signal represents a true airspeed rate that yields an optimal flight path for the aircraft to exit the windshear condition.

Abstract: An improvement to a Flight Management System (FMS) for an aircraft is described. The improvement comprises: a system coupled to the flight management system for accepting flight data information, including a required time of arrival, and for generating therefrom an estimated arrival time and deriving from the estimated arrival time a signal representative of the required airspeed needed to allow the aircraft to reach a particular point at the required arrival time; and a system for receiving the signal and for generating an output signal for modifying the actual airspeed of the aircraft to correspond to the required airspeed. The signal is derived by applying to the actual airspeed a correctional factor which is a function of the estimated arrival time and the required arrival time. The correctional factor is generated from the ratio of the difference of the estimated arrival time and the required arrival time to the required arrival time.

Abstract: A synthetic speed stability subsystem for maintaining the speed and phugoid stability of an inherently unstable aircraft is connected to a main flight control system. The speed stability subsystem uses the pitch and roll angles, and the equivalent air speed of the aircraft for calculating a synthetic speed stability signal, which is fed to the main flight control system, for controlling the stability of the aircraft.

Abstract: An aircraft control system that simultaneously controls vertical speed (or flight path angle) and airspeed or Mach number by supplying the vertical speed (or flight path angle) command to the autothrottle system and the airspeed or Mach command to the autopilot pitch channel. A thrust reference computer provides an approximation of the thrust required to maintain the reference vertical speed (or flight path angle) and a vertical speed error signal in closed loop fashion provides a vernier adjustment to the approximation to provide the autothrottle channel command.

Abstract: An improved system and technique is disclosed which enables an aircraft control system to bring an aircraft to hover with no direct measurement of ground speed. The system includes a device for numerically calculating a value for ground speed based on a differentiation of aircraft position as measured from conventional ground reference navigational aids. The computed value of ground speed is compared with values representing heading and true air speed to generate a computed value of wind. The computed value of wind is then resolved into vector components of headwind and crosswind and the headwind component and air speed are summed to provide a signal used to control aircraft speed until zero ground speed is achieved.

Abstract: The invention provides for rapid response and reliable detection of vertical windshear during the takeoff and approach phases of flight. Standard instrumentation available on many aircraft is used to calculate the down-draft acceleration and its effect on the aircraft's performance capability. The invention utilizes inputs from vertical acceleration, true airspeed, pitch angle, and angle of attack sensors. The rate of change of vertical wind is derived from the sensed signals and used to determine the margin between the aircraft's present performance capability and the predicted performance capability at stick shaker speed.

Abstract: An improved method for the automatic acceleration of an aircraft to a preselected speed is described. At any point in the climb portion of flight, a capture of a computed altitude that is increased at a specified rate is performed to provide optimal acceleration.

Abstract: There is disclosed a system and technique which enables an aircraft (helicopter or VTOL) to be more easily controlled for maintaining precise position or velocity in a hover condition. The system includes operational logic and decision making circuitry which reduces pilot workload by sensing pilot intent based upon the control stick movement and mode selection of the aircraft. The system will automatically hold a given hover position, automatically hold a given hover velocity (ground speed), or allow the aircraft to be manually maneuvered to a new desired hover position or velocity. The system also enables the aircraft to either hold a new velocity or return to a previous velocity. This is all controlled through the automatic flight control system and by sensing the force or displacement of a pilot's control stick in the aircraft.

Abstract: Aircraft gyro (20, 22) signals .theta. and .phi., representative of pitch and roll attitude, respectively, and accelerometer (24, 26, 28) signals a.sub.x, a.sub.y, a.sub.z, representative of longitudinal, lateral, and normal acceleration, respectively, are processed (30, 32, 34, 36, 38, 40) to produce signals a.sub.GSLO, a.sub.GSLA, and a.sub.GSN, representative of the longitudinal, lateral, and normal groundspeed rate components, respectively. The component signals are summed (50) to produce a signal representative of total aircraft groundspeed rate.

Abstract: A cruise speed control apparatus for aircraft wherein small differences between the target Mach command and the actual Mach number of the aircraft are used to displace the aircraft from its reference altitude to either increase or decrease actual Mach number in the short term. Long term differences are corrected through a special isolation filter to separate the engine control loop and pitch control loop dynamics and an integration technique to adjust the automatic throttles about a thrust target for the commanded Mach.Large differences between the target Mach and the actual Mach or large changes in the commanded Mach are compensated for by a non-linear gain that effectively increases or decreases the target thrust to cause the aircraft to accelerate or decelerate to the commanded Mach.

Abstract: A helicopter flight control system employs coupled torque limiters in the rotor cyclic pitch axis and collective pitch axis for airspeed and vertical path control, respectively. When the collective torque limit is reached, the cyclic pitch axis is automatically transferred to favor vertical path control. A synchronizer circuit is provided for assuring smooth acceleration transition to reduce accrued airspeed errors when the engine torque limit is no longer commanded.

Abstract: A system which provides an increased minimum aircraft pitch attitude during take-off or go-around operations in the event that an unsafe wind shear condition is encountered. A control signal from a wind shear warning system, indicative of a dangerous wind shear condition, is fed to a switching device which controls the velocity command signal to the flight director pitch control. This switching device, in response to the wind shear signal, changes the velocity command to a lower predetermined value, such that the attitude of the aircraft is automatically increased to handle the wind shear encounter.

Abstract: A full time three-cue (roll control, pitch control and collective control) for helicopters flight director and/or autopilot wherein the collective control cue is automatically activated when airspeed is below a predetermined low value or above such value when path errors naturally or manually produced, or airspeed errors exceed predetermined values in magnitude or time.

Abstract: An aircraft speed control system for use with an automatic throttle position control system and automatic flight control system permits capturing and maintaining a commanded airspeed during the capturing of a desired altitude from either climbing or descending flight. The system manipulates the throttles at a variable rate dependent on the difference between the actual thrust of the aircraft and the desired cruising thrust at the selected airspeed and inversely proportional to the actual altitude rate. A signal derived from thrust error and altitude rate signals is utilized to generate a limiter control signal which is combined with an engine pressure ratio signal to generate a drive signal for urging the aircraft to capture precisely the commanded airspeed.

Abstract: An aircraft is provided with wind velocity measuring equipment which measures the wind velocity both (1) close to the aircraft and (2) at a considerable distance such as one-half mile or a mile away from the aircraft; and a large difference in these two measured velocities indicates dangerous windshear conditions. Either a warning signal is given to the pilot, or automatic control apparatus is actuated, to avoid crash conditions. A single pulsed carbon dioxide (CO.sub.2) laser velocimeter may be mounted in the aircraft for measuring both the close-in and the distant wind speeds. The laser optic focus is shifted between the near and far measurements, and the return signal is time gated to increase signal-to-noise ratio.

Abstract: An aircraft automatic flight control system (AFCS) includes a pair of fast, limited authority inner loop actuators responsive to signals indicative of aircraft attitude or other flight parameters such as airspeed, the inner loop being recentered by an outer loop actuator responsive to attitude or other aircraft parameter-indicating signals (54,55). Commands applied to the outer loop are applied in a lagged fashion in opposite direction so as to drive the inner loop actuators back toward the center of their authority. The rate of response of the outer loop is adaptive in response to magnitude of inner loop input (101, FIG. 2). A pitch bias command is provided to the inner loop as a function of airspeed multiplied inversely with collective pitch, and as a function of the rate of change of collective stick position, so as to provide a positive static pitch trim gradient and decouple collective pitch from the longitudinal cyclic pitch channel.

Abstract: An improved flight director go-around mode adjusts the collective stick position in a closed loop to increase lift to a desired value. If the engagement airspeed is below the maximum rate of climb airspeed, the airspeed is increased towards the maximum rate of climb airspeed at a moderate rate. When the maximum rate of climb airspeed is attained, or if the engagement airspeed is at least the maximum rate of climb airspeed, and the rate of climb is satisfactory, the airspeed is maintained. If the engagement airspeed is greater than the maximum rate of climb airspeed and the desired rate of climb is not achieved within ten seconds, the airspeed is decreased towards the maximum rate of climb airspeed. Heading or course is automatically maintained when go-around is engaged.

Abstract: A Mach hold control circuit for an aircraft autothrottle system provides capture of a Mach number and control thereto while providing a low level of throttle activity also stabilizing the aircraft at maximum range cruise (MRC) Mach numbers and above. The Mach hold control law utilizes a Mach error signal, flight path acceleration signal, average engine EPR signal, and associated logic inputs and when interfaced with the autothrottle system provides a throttle rate command to the aircraft engines via. the throttle and engine control system thereby modulating engine thrust to provide control to desired flight Mach number.

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: A digital fuel control (53) for a helicopter engine (20) controls fuel flow (52) to the engine in response to a turbine reference speed (62) determined in a normal mode (FIG. 5) to be a rated speed, in a fade-in mode (FIG. 6) to be incremented (117, 120) to an estimated optimum minimum speed (114, 115, 125), in an optimizer mode (FIG. 7) to be incremented (138) in a direction (137) leading to least fuel consumption (135), and in a fade-out mode (FIG. 8) to be incremented (151, 153) back to rated speed (154). The invention provides an engine reference speed which results in minimum fuel consumption during cruise flight.

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: 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: This system permits speed variation within certain constraints. The minimum speed is derived from a stall avoidance or acceleration margin condition and the maximum speed may be the lower limit of the transonic region or other design limit. Assuming the throttle is set at or near a trim value, adjustments need only be made if the terrain following flight path is tending to drive the speed to one of the two velocity extremes. Velocity predictions are based on predicted kinetic energy being equal to the difference between the current kinetic energy and the potential energy to the profile extreme. The throttle is adjusted when the predicted velocity is outside the limits to add or remove the required amount of energy.

Abstract: A method is provided for obtaining minimum aircraft fuel consumption per unit of time by flying at the minimum drag speed. The computation of the minimum drag speed is based on the principle that in an aircraft in level flight with a constant power setting, wherein a differential exists between thrust and drag, the resultant longitudinal acceleration will exhibit an increasing magnitude when the aircraft is below minimum drag speed and a decreasing magnitude when the aircraft is above minimum drag speed. Accordingly, longitudinal accelerations are induced in an aircraft through the use of incremental thrust changes, and the rate of change of said accelerations are compared with airspeed in order to determine the minimum drag speed in accordance with said principle. The aircraft is then maintained at the minimum drag speed which permits it to stay aloft at minimum fuel consumption rates.

Abstract: A turbulence compensated aircraft throttle control system is augmented with switching logic and signal processing to subtantially decrease the magnitude of wind shear-induced airspeed errors and the time required to recover from such airspeed errors. The disclosed arrangements include a throttle controller having a speed control channel that is responsive to airspeed error and a turbulence compensation channel that is responsive to aircraft airspeed and longitudinal inertial acceleration of the aircraft. A signal representative of the wind shear being encountered by the aircraft is derived within the turbulence compensation channel (or from signals provided thereby) and is processed to form a wind shear compensation signal that is coupled into the speed command channel whenever the airspeed error exceeds a predetermined amount. The wind shear compensation signal supplements the airspeed error signal to substantially increase the magnitude of the throttle command signal.

Abstract: In a helicopter automatic flight control system having both automatic pitch attitude retention (70, 71) and automatic airspeed hold (84) and responsive both to pitch attitude error (206) and integrated (241) airspeed error (230), saturation of either the attitude error or integrated airspeed error circuitry is avoided by sensing (171) integrated airspeed error buildup to a threshold magnitude (which may be a significant fraction of the instantaneous authority of the automatic flight control system), and causing (169, 167) automatic slewing of the pitch attitude reference signal toward the current pitch attitude and reduction of the integrated airspeed error. In a disclosed embodiment, the correction of attitude reference and reduction of airspeed error is effected by utilizing an equal effective time constant (220, 221; 258, 259) for both actions over the same period of time (170, 168, 175).

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: An avionic system for producing the most economical engine thrust and airspeed settings in readily usable form during a jet aircraft flight is disclosed. The pilot inserts: the elevation of the destination airport; the zero fuel weight of the aircraft; the reserve fuel needed for the flight; the outside air temperature at the departure airport; and, a flight index number. The flight index number represents a chosen relationship between fuel costs and trip time-related costs. The system also receives data from various aircraft subsystems and sensors and uses the information it receives, and stored information, to produce signals representing the most economical engine thrust setting and airspeed for the phases of a flight. The thrust setting and airspeed signals drive bugs on thrust and airspeed indicators and/or used to control autothrottle/autopilot systems.

Abstract: Apparatus for monitoring the acceleration of an aircraft moving along the ground includes a linear accelerometer (FA) and a rate gyroscope (RG). The accelerometer FA is fixed to the frame of the aircraft with its sensitive axis substantially horizontal, and circuit means A3, A4, are provided to null any output when the aircraft is at rest. The rate gyroscope RG is arranged to correct for any misalignment of the axis of the accelerometer, and further circuits A1, A2 null the output of the gyroscope while the aircraft is at rest. An amplifier A5 adds the outputs of the accelerometer and gyroscope channels, and correction amplifier A6 and unit AD correct the output of the summing amplifier A5 for aerodynamic drag resistance of the aircraft at any instant. The corrected output is applied to a suitable indicator such as a meter M.

Abstract: An improved cruise speed control system for commercial jet aircraft is described. The basic control terms for the pitch loop are altitude error, altitude rate and washed-out speed or Mach. The basic control terms for the speed loop are Mach error, Mach rate and integrated Mach error. Other speed loop functions include a gain term which increases at low engine response rates, based on either engine rpm or engine pressure ratio (EPR), to compensate for throttle linkage hysteresis, a versine term to compensate for increased drag in turns, an inner EPR loop for damping the outer speed loop, a variable gain term as a function of Mach error to facilitate changes of commanded Mach, and a switch to disconnect Mach error and Mach rate and to increase the nominal value of EPR during periods of air turbulence.

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 system to warn an aircraft pilot of a hazardous wind shear condition in which the rate of change of airspeed is compared to the ability of the aircraft to respond thereto. Any difference therebetween that exceeds a predetermined threshold is used to activate a suitable alarm or compensation device. Additional refinements include correcting the inertial speed inputs for vertical components and autopilot induced throttle changes, and correcting the air speed inputs for short term fluctuations.

Abstract: The pitch and roll channels of the stability augmentation system (inner loop) of a helicopter automatic flight control system are utilized to provide positional and attitude stability at low speeds and hover, and to reduce the attitude effects of wind gusts during essentially level, forward flight at cruise speeds. In the longitudinal or pitch channel, true longitudinal acceleration is summed with washed-out vertical gyro pitch in level flight below 60 knots, and washed-out vertical gyro pitch is used alone above 60 knots; in the lateral or roll channel, true lateral acceleration is summed with vertical gyro roll at speeds below 60 knots in essentially level flight, and vertical gyro roll is inputted alone above 60 knots whenever the heading hold logic has not been disengaged (indicating a roll has not been commanded to perfect a turn); thereby to provide positional and attitude stability at low speeds, and to provide attitude stability at cruise speeds.

Abstract: A system for processing signals representative of airspeed error and inertial longitudinal acceleration in first and second channels, respectively, and providing cancellation of the turbulence-induced components of the respective signals. Shear detection and compensation circuits are provided in the system for reducing speed wandering in moderate and heavy turbulence. A circuit processing the signal .DELTA.V from the shear detector circuit is utilized to provide a gust bias signal input in the system.

Abstract: Command from engine rating control prevents throttle position from exceeding the value at which the engine operates at its rated power. Flare initiation changes the throttle command signal from a closed loop control signal to a fixed number of degrees per second retard rate, thereby overriding an aft limit switch signal allowing throttles to reach the idle position. A servo feedback arrangement utilizes a tachometer signal and an engine PLA (power level angle) signal to optimize servo performance and overcome undesired control cable characteristics.

Abstract: The yaw channel of a helicopter, which includes a yaw servo having a yaw trim valve operable to automatically hold heading, and at cruise speeds alternatively operable to provide controlled yaw for coordinated turns, which is normally disengaged by switches located on the pedals, is selectively allowed to remain engaged at cruise speeds so that if the pilot induces commands in yaw by means of the pedals, the pedal linkage must be forced against the position of the trim piston established by the heading hold or coordinated turn input commands to the yaw trim valve, thereby giving the pilot pedal force feel as a consequence of the resilient connection to the trim piston, which provides an indication to the pilot of the amount of side slip he is creating, thereby to avoid destructive overloading of the tail rotor.

Abstract: A Mach hold control circuit for an aircraft autothrottle system provides capture of a Mach number and control thereto while providing a low level of throttle activity also stabilizing the aircraft at maximum range cruise (MRC) Mach numbers and above. The Mach hold control law utilizes a Mach error signal, flight path acceleration signal, average engine EPR signal, and associated logic inputs and when interfaced with the autothrottle system provides a throttle rate command to the aircraft engines via. the throttle and engine control system thereby modulating engine thrust to provide control to desired flight Mach number.

Abstract: A system for processing signals representative of airspeed and inertial longitudinal acceleration in first and second channels, respectively, and providing cancellation of the turbulence-induced components of the respective signals. Shear detection and compensation circuits are provided in the system for reducing speed wandering in moderate and heavy turbulence. A circuit processing the signal .DELTA.V from the shear detector circuit is utilized to provide a gust bias signal input in the system.

Abstract: A system for processing signals representative of airspeed error and inertial longitudinal acceleration in first and second channels, respectively, and providing cancellation of the turbulence-induced components of the respective signals. Shear detection and compensation circuits are provided in the system for reducing speed wandering in moderate and heavy turbulence. A circuit processing the signal .DELTA.V from the shear detector circuit is utilized to provide a gust bias signal input in the system.

Abstract: An aircraft air speed signal is differentiated to provide a signal related to rate of change of air speed. This signal is added to a signal related to aircraft barometric altitude change with the sum signal being compared against aircraft radio altitude to generate warning if the aircraft rate of descent is excessive for the conditions encountered.

Abstract: A bias actuator, such as an extensible link, in the longitudinal cyclic pitch channel of a helicopter is provided with inputs as a function of airspeed multiplied inversely with collective pitch, and as a function of the rate of change of collective pitch stick position, so as to enforce positive angle of attack and speed stability and positive static pitch trim gradient and to decouple collective pitch from the longitudinal cyclic pitch channel at cruise airspeeds, the invention compensates, inter alia, adverse control effects of tail stabilizer surfaces at cruise speeds. A pair of indicators display bias commands and actual bias responses.

Abstract: A control system including both a method and apparatus for use on an aircraft during flight utilizes real-time data provided by sensing equipment on the aircraft to iteratively generate values for an efficiency parameter. The aircraft controls are adjusted after each iteration, and successive values of the efficiency parameter are compared until such comparison shows that the parameter has been substantially optimized. Iterations may then continue without corresponding control adjustments until comparison indicates that a current parameter value differs by a predetermined magnitude from the previously determined optimum value, at which time control adjustments resume in order to bring the efficiency parameter to a new substantially optimum parameter value.

Abstract: A maneuver detector generates a maneuver-detect signal when signals representative of elevator deflection and flight path deviation are representative of a deliberate maneuver condition and no maneuver-detect signal when the relationship of the two signals is indicative of elevator deflection such as to oppose a flight path deviation, e.g., as caused by turbulence condition or configuration change.

Abstract: Terminal guidance of vehicles is accomplished by accurately determining true position and speed of the vehicle from terrain contour measurements and updating a dead reckoning navigation system with precision to permit navigation by following a programmed flight path. A narrow beam radar altitude sensor measures vehicle clearance altitudes and a reference altitude sensor measures the vehicle clearance above a reference level. These measurements are input to a digital processor for comparison to stored digital terrain contour reference data. Recursive data matching is performed in the digital processor by a nonlinear Kalman filtering technique to provide vehicle position and vehicle velocity correction signals to a navigation controller that generates steering commands to the vehicle control system. Three vehicle position and three vehicle velocity signals are generated and updated in the nonlinear Kalman filtering technique to give near real-time three dimensional position and velocity information.

Abstract: A system of airplane instrumentation utilizing devices and procedures for dealing with wind shear on the final approach to a landing. The system is designed for use in a like manner on all approaches for landing to assure that a safe, stable speed be used during all landing approaches, and that the Pilot be apprised of the conditions his airplane is flying through at all times during the approach. The primary aim is to provide instrumentation which will aid the Pilot in achieving safe approach criteria, give him information on which to base his judgment, and eliminate accidents on the final approach due to wind shear.

Abstract: The inventive system requires that normal approach indicated airspeed and a predetermined approach groundspeed be used as the approach criteria, whichever is the least, compared to its own predetermined index value. These two values are the commanding functions fed to a fast/slow indicator and to any auto-throttle device on the approach, along with a "caution tailwind" warning device to warn the pilot whenever the groundspeed exceeds true airspeed by 5 knots or more, for example. If this warning activates, he should consider cancelling the approach and choose an approach from a different direction, determined by surface wind and his drift at the time of cancellation. This condition is caused by a tailwind component at altitude, the value of which the pilot can determine from his airspeed and groundspeed indications.

Abstract: A control system for automatically activating the flight control surfaces of a STOL aircraft that utilizes upper surface blown flaps when the aircraft executes a STOL landing or takeoff maneuver with one engine inoperative in that the engine does not provide the desired or scheduled amount of thrust. The system monitors internal engine pressure of each engine to detect such engine failure and deploys the upper surface blown flaps, conventional flaps and spoilers used as direct lift control devices to provide a relatively uniform lift distribution across the aircraft wing and hence lower induced drag. When the aircraft executes a STOL takeoff procedure with an engine, that does not provide the proper thrust level the upper surface blown flap located aft of that engine is automatically extended to a position that matches the position of those conventional flaps located outboard of the inoperative engine.

Abstract: A circuit for generating a signal proportional to the ground speed and track angle of an aircraft derives a signal from a node in a coherent or vector filter having a position vector input and output. The filter utilizes at least two integrators which integrate respective components of the quadraturized input vector, the outputs of the integrators being added and fed back to the input to be added as an error signal to the input vector. A second filter samples the input to the integrators, and filters the sampled signal to produce a signal proportional to the ground speed of the aircraft.