Abstract: A calculation system for calculating the control signals which are designed to perform a frequency-dependent weighting of the angular velocity signals and the angular position signals. The angular velocity indicators are preferably used for stabilization in a high frequency band while the angular position indicators are suitable for stabilization in a low frequency band. A further calculation system which is designed to perform the frequency-dependent weighting such that the control signals for frequencies below a certain frequency are substantially determined by the angular position signals and the control signals for higher frequencies are substantially determined by the angular velocity signals.

Abstract: The present invention relates to a flight control device for an aircraft comprising a control (2) and a means for actuating a controlled member (RP, RQ) to which a command is applied. According to the invention, said device (1) additionally includes a sensor (E) for determining a second value that is representative of the control executed by the aircraft (He) with respect to the control axis, and second means (M2) which determine: as long as the second value is lower than or equal to a reference value, a first trim command that is proportional to the actuation of the control (2); and when the second value is higher than the reference value, in addition to a second trim command, a speed command that is proportional to the additional actuation over and above said second value.

Abstract: An arithmetic processing method and system in a wide velocity range flight velocity vector measurement system using a square truncated pyramid-shape five-hole Pitot probe. Approximation equations that determine attack angle &agr; and sideslip angle &bgr; in the form of third-order equations concerning attack angle pressure coefficient C&agr; and sideslip angle pressure coefficient C&bgr;, which are known numbers, are expressed in the form of a polynomial equation concerning Mach number M, where the coefficients are obtained from a lookup table.

Abstract: A process and a device for verifying the consistency of the measurements made by an angle-of-attack probe (2) mounted on an aircraft. The device (1) includes:first system (3) for computing a first coefficient of lift of the aircraft from a measurement from the probe (2) and from data relating to the aircraft;second system (5) for computing a second coefficient of lift from information about the aircraft;system (6) for computing the difference between the first and second coefficients of lift and for deducting therefrom that the measurement is or is not consistent.

Abstract: A method for determining the initial conditions for an inertial measurement nit (IMU) of a second vehicle launched from a wing of a first vehicle is provided. The method includes the steps of defining a state vector x as including (a) the rotation .zeta. of the computed coordinate axes with respect to the real coordinate axes of the second vehicle and (b) the projection .delta..alpha. along the Z axis of the first vehicle of the rotation of the second vehicle from its nominal coordinate axes to its real coordinate axes. A measurement z is defined as the projection .delta..beta. of a rotation angle .beta., along the Z axis of the first vehicle, between the nominal coordinate axes and a current computed coordinate axes. The method also includes the steps of estimating x over time with a Kalman filter, wherein the projection .delta..beta. is the measurement vector and the state vector x changes only due to random noise and processing x to produce the attitude about the Z axis of the first vehicle.

Abstract: An aircraft modal suppression system which recognizes that the frequency and phase of the body bending mode varies when the weight of the aircraft differs from the design gross weight. An active damper notch filter which is tabulated as a function of aircraft gross weight is utilized, thereby enabling not only the frequency, but also the width and depth of the notch filter to vary according to the gross weight of the aircraft.

Abstract: An air active control aircraft having an air three-dimensional true airspeed detection system composed of an air data sensor probe in the form of a truncated pyramid-shape Pitot probe and an air flight velocity operation processor for calculating an air flight velocity vector from three-dimensional air pressure information detected by the air data sensor probe, airframe motion detection sensors for detecting an airframe motion, and an on-board control computer for generating a flight control law. The on-board control computer inputs an air flight velocity vector signal obtained from the air flight velocity vector device into a control-surface control system in parallel with airframe motion detection sensor signals, and presumes a flight motion induced by a change in air to generate the flight control law for quickly carrying out air flight stability control.

Abstract: A failure of any one of three swashplate actuators of a helicopter rotor blade is detected. Once such a detection is made, the position of this nonfunctional swashplate is locked and measured. The inputted commanded swashplate collective position, commanded swashplate x-axis rotational position, and commanded swashplate y-axis rotational position are then passed to a failure-mode control matrix. The failure-mode control matrix computes swashplate actuator commanded positions for the two operable swashplate actuators so that aircraft attitude control is maintained. These two swashplate actuator commanded positions instruct positional movement of the rotor blade swashplate to thereby meet the commanded swashplate x-axis rotational position and the commanded swashplate y-axis rotational position which will control attitude. A quasi-swashplate-collective-position corrector computes the quasi-swashplate collective position that will occur because of the successful control of the aircraft's attitude.

Abstract: An integrated fire and flight control (IFFC) system determines a ballistic firing solution based on the position of targets relative to a helicopter and also based on the type of weapons to be fired. An elevation command is determined based on the required change in helicopter attitude to achieve the ballistic firing solution that, combined with the estimated time required to perform the aim and release of weapons, provides an estimate of deceleration and velocity loss that will occur. A forward acceleration and velocity profile is determined based on the desire to make a symmetrical maneuver sequence involving a nose down acceleration to achieve the acceleration and velocity profile that will be canceled by the subsequent deceleration and velocity loss during the pitch up maneuver to the ballistic firing solution.

Abstract: A vertical control system for a rotary winged aircraft receives inputs from a displacement collective stick and a sidearm controller. The system provides a set point for the vertical rate of change of the helicopter as a function of a vertical lift command signal from the sidearm controller. The set point is used as a reference for an altitude rate of change feedback path, and an integrated value of the set point is used for an altitude feedback path. The set point is also input to a feedforward control path having an inverse vehicle model to provide a command signal indicative of the command for aircraft collective pitch necessary to achieve the desired set point. Signals from all three paths (i.e., the altitude rate of change feedback path, the altitude feedback path, and the feedforward path) are summed to provide a signal to backdrive the displacement collective which controls main rotor collective pitch.

Abstract: In an aircraft, there is included a Flight Management System (FMS), Autopilot and Autothrottle for controlling the aircraft. The apparatus has a plurality of outputs for definition of the real-time targets, controlled by the Autopilot and Autothrottle, to guide the vertical position of the aircraft to a desired vertical position along the desired vertical flightplan (or profile) according to a set of operational procedures. The FMS includes an apparatus that comprises an element which provides information denoting actual vertical position of the aircraft, and an element which generates information specifying the desired vertical position of the aircraft along the predetermined desired flightplan.

Abstract: A control system and method for causing a spacecraft (10) initially spinning about a principal axis of inertia (H) to transition to spin about an arbitrary command axis (3) is presented in which the capture maneuver is performed in a way to preserve spacecraft attitude knowledge without sensor or attitude propagation by using a simple rate feedback loop. The capture is accomplished by applying a step torque about axes (1) and (2) transverse to the desired spin axis (3) creating an initial nutation. The nutation is subsequently damped actively by closing a rate feedback loop with a low pass filter and applying transverse torques proportional to the transverse nutational rate.

Abstract: A helicopter flight control system (21) includes a model following control system architecture which operates in a velocity command mode at low ground speeds. The control system processes information from a variety of helicopter sensors (31) in order to provide a command signal to the main rotor (11) of the helicopter which results in a ground speed which is proportional to the input provided via a sidearm controller (29).

Abstract: System for controlling roll and yaw of an aircraft. The system includes a device capable of elaborating, from electric signals respectively representative of the position of a first voluntary actuation member, the rolling speed, the attitude, the yaw speed, the sideslip and of the position of a second voluntary actuation member, a single electrical order for roll control formed by a linear combination of the electric signals. There is a device capable of elaborating, from the same electric signals, an electrical order for yaw control formed by a linear combination of the electric signals. There is also a device which makes it possible to combine the electrical order for yaw control and a mechanical order coming directly from the second voluntary actuation member.

Abstract: A plurality of two-axis rate gyros are arranged in relation to an aircraft-fixed coordinate system such that they redundantly supply angular rate information. A plurality of accelerometers supply correspondingly redundant acceleration information. First signal processing means comprise means for failure detection and elimination, such that angular rate and acceleration information subjected to error are eliminated. The angular rate and acceleration information thus cleared from errors supply stabilization signals for the autopilot. Second signal processing means obtain the angular rate and acceleration information cleared from errors and integrated if required, and therefrom supply heading and attitude reference signals.

Abstract: A flight control system utilizing multi-controlled surfaces to provide the necessary control power and feedback logic to stabilize the aircraft with minimal noise amplification. In addition, a unique performance optimization loop is integrated into the stability logic to position the multi-control surfaces for optimum maneuver performance.

Abstract: Angular momentum exchange apparatus comprising, in combination: a massive rotor of substantially spherical configuration having at least an outer surface of electrically conductive and magnetizable material; a housing for the rotor; driving apparatus carried by the housing for cooperation with the surface to cause angular acceleration of the rotor about each of a plurality of axes; and means supporting said rotor in said housing for rotation free from contact there between.

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 adjustable mounting tray for installation of an aircraft gyroscopic and/or inertial reference apparatus, comprises, a baseplate member mounted so that it is substantially level in roll and pitch on the equipment shelf or rack of a levelled aircraft. A top plate or tray member is pivotally mounted on the baseplate for azimuthal adjustment thereon. The aircraft is pitched up or down and the top plate rotated in azimuth to remove any roll/yaw cross-axis coupling thereby assuring precision longitudinal axis alignment.

Abstract: In an aircraft automatic flight control system, automatic shutdown (42) of the roll axis thereof (FIG. 1) as a consequence of faults detected therein also provides automatic shutdown of the yaw axis thereof (180) in the same fashion as detection of faults in the yaw axis (171, 167) provides shutdown of the yaw axis. Coupling of the roll axis shutdown into the yaw axis shutdown allows determining which of three axes cause lighting of a single trim shutdown indicator by resetting the yaw shutdown register (145) and simultaneously resetting both the pitch and roll shutdown registers by means of a single cyclic pitch control switch. Automatic yaw trim outer loop and yaw inner loop stability systems are disclosed (FIG. 2).

Abstract: A hybrid analog/digital autopilot utilizing analog inner loops in each control axis of the aircraft and a digital processor for providing outer loop commands and inner loop gain augmentation commands to the inner loops. The command from the processor to each inner loop is buffered by an adaptive rate limit circuit that initially transmits high frequency commands and over a predetermined time interval limits the command rate to a safe low value. Alternatively, the adaptive rate limit buffer transmits the high frequency command up to a predetermined attitude limit and thereafter transmits a command limited to a low safe rate.

Abstract: A four axis force stick provides signals indicative of force applied to the stick in an axis corresponding to a control axis of an aircraft, including pitch, roll, yaw and lift/speed. The force-related signals are applied through proportional and integral gain signal paths to operate electrohydraulic servos that control the aerodynamic surfaces of the aircraft, such as the cyclic and collective blade pitch of the main rotor and the tail rotor blade pitch of a helicopter, or the ailerons, rudder, elevator and thrust of a fixed wing aircraft. Signal conditioning provides a dead band to avoid integrating minute, inadvertent force stick signal outputs, and vernier sensitivity at low forces with high gain at high forces. Analog and digital embodiments are discussed. The relationship between this wholly new mode of aircraft control and ancillary aircraft functions, such as ground steering, autopilot and stability functions, are also discussed.

Abstract: In an automatic flight control system, failure of dual inner loop actuators (12, 13) to track position (22, 23) within a permissible tolerance (182) of each other will cause automatic shut down (185, 190) of an outer loop actuator (37) which is responsive (61) to the same proportional signals (54, 55) as are the inner loop actuators. The invention is disclosed in a system in which automatic flight control positioning of the control surfaces of the aircraft is through a fast, limited authority inner loop, the authority of which is centered by repositioning of the outer loop.

Abstract: An aircraft automatic flight control system having a roll channel (FIG. 1), a yaw outer loop trim system (bottom of FIG. 2) and a yaw stability inner loop (top of FIG. 2) provides proportional (129) and integral (114) lateral acceleration inputs to the yaw trim system (106, 93) during coordinated turns, and provides proportional (130) and lagged (131) roll rate inputs to the trim system to provide initial coordination to the turns.

Abstract: In an aircraft automatic flight control system, a flight path controlling, full authority outer loop actuator (37) operated in response to the integral (41) of commands thereto, is shutdown (111, 113-115) in response to the sensing (31, 32) of force on the related pilot control member (27). After removal of force (118), the outer loop is continued to be shut down for a time interval (119) to allow the aircraft to resettle toward the trim point before building up error in the integrator, unless high input demand (122) is indicated.

Abstract: In an aircraft automatic flight control system, proportional commands (54, 55) provided to fast, limited authority inner loop actuators (12, 13) are integrated (41), and when the integrator output indicates that the inner loop actuators 12, 13 have been driven a certain percentage of their authority, a comparator (130, 132) activates a pulse generator (137, 138) to provide timed excitation of an actuator (150), thereby to position the aircraft control system outer loop by a commensurate increment. Driving the actuator for a longer time than the desired pulse width is detected (165-169) and causes automatic shutdown (190) of the actuator. Resetting the integrator at the start of each pulse (162, 104), and pulse-controlled gating of the pulse circuits (172, 135, 136) allow sensing of authority transitions which occur within a pulse, and permit a subsequent pulse in response thereto.

Abstract: In an aircraft automatic flight control system (FIG. 4) the application of force to a control member (35R, FIG. 5) forces (222, 216, 217, 212, 213) the flight path controlling, full authority outer loop to be disengaged. Once disengaged by force, the outer loop remains disengaged (224) until force is removed (225) and a signal indicates (226) a need to reestablish the outer loop. Reestablishment may be indicated by beeping (228) or by the controlled attitude (54R, 55R) being restored to within a predetermined level (230).

Abstract: An aircraft automatic flight control system includes a pair of fast, limited authority inner loop actuators (12, 13) responsive to signals (52-55) indicative of aircraft attitude (68, 69) or other flight parameters such as airspeed (84), the inner loop being recentered by an outer loop actuator (37) responsive to attitude or other aircraft parameter-indicating signals (54, 55). Commands (40) applied to the outer loop are applied in a lagged fashion (58, 59) in opposite direction so as to drive the inner loop actuators (12, 13) back toward the center of their authority. The rate of response of the outer loop (FIG. 2, FIG. 5) is adaptive in dependence upon airspeed (93, 96, 212, 213) and in response to magnitude of inner loop input (101, FIG. 2). An integral gain (41), pulsed (39), open loop drive of the outer loop actuator (37) and outer loop automatic shutdown (38) are disclosed.

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: In an aircraft automatic flight control system (FIG. 1) beeping of the reference voltage in attitude synchronizing and beeping circuits (70, FIG. 4; 70R, FIG. 6) is inhibited (196, 201; 278, 282) in response to proportional commands (54, 55; 54R, 55R) in excess of a predetermined magnitude (183-186, 283-286). Beeping is inhibited only in the direction of the high proportional command, but not in the other direction. In a dual system (FIG. 1) pitch attitude beeping is inhibited only if both channels of the system have excessive proportional commands (195, 200, FIG. 3) whereas roll attitude beeping is inhibited if either channel has excessive proportional command (294, 295).

Abstract: A helicopter pitch axis autopilot system, including airspeed hold at cruise speeds and pitch attitude hold below cruise speeds, includes integrated longitudinal acceleration drift corrected by heavily filtered Pitot static airspeed as a filtered airspeed reference, use of a beeper to nudge the airspeed reference above cruise speeds or the pitch attitude reference below cruise speeds, resynchronizing of airspeed reference, pitch attitude reference, pitch autopilot integrator and stick trim position reference, momentarily in response to airspeed transitions between cruise and sub-cruise speeds or in response to initiation of beeping, and continuously during trim release.

Abstract: Electromagnetic method and apparatus to accurately control the orientation of a platform according to two axes wherein pivoting of the platform about two orthogonal axes passing through its center is effected by electromagnetic means, with the servo-control being obtained by using a detector responsive to the angle of deviation from a reference direction, an amplifier, a low-pass filter, a phase lead filter and power amplifiers supplying currents to the electromagnetic devices. The method and apparatus is particularly adapted to the orientation of platforms carrying means such as aerials or inertia wheels intended for piloting a space vehicle.

Abstract: A plurality of inertial measuring unit (IMU) modules (41A, B, C and D) each comprising gyros and accelerometers (61, 65 and 67) for sensing inertial information along two orthogonal axes, are strapdown mounted in an aircraft, preferably such that the sense axes of the IMUs are skewed with respect to one another. Inertial and temperature signals produced by the IMU modules, plus pressure signals produced by a plurality of pressure transducer modules (43A, B and C) and air temperature signals produced by total air temperature sensors (45A and B) are applied to redundant signal processors (47A, B and C). The signal processors convert the raw analog information signals into digital form, error compensate the incoming raw digital data and, then, manipulate the compensated digital data to produce signals suitable for use by the automatic flight control, pilot display and navigation systems of the aircraft.

Abstract: An aircraft ejection seat having pitch, roll, and yaw control. Two gimbal rocket motors are attached to an aircraft ejection seat. A servo control circuit rotates the rocket motors in response to command signals.

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 set of two two-degrees-of-freedom rate gyroscopes and three linear accelerometers are assembled in a single module adapted to be mounted within a single aircraft electronics control unit, the unit comprising a strapped-down attitude and heading reference system. The module base provides a common keyed support for the two pre-calibrated gyros and three accelerometers in intimate mechanical and thermal association. The two gyros are oriented in the base and the base oriented in the aircraft so that the spin axis of one gyro is oriented parallel to the aircraft Z axis and that of the other gyro parallel to the aircraft Y axis while the gyro pickoffs and torquers (input and output axes, respectively) are rotated or skewed forty-five degrees about the spin axes to positions such that the input and output axes lie along the slant heights of a forty-five degree half angle right circular cone, the axis of which lies along the aircraft X axis.

Abstract: The present invention relates to a method and apparatus for detecting the earth's static electric field and determining the contour of its equipotential lines and surfaces and for utilizing the detected field as a reference for other measurements. In particular, the contour of the field can be determined by sensing the potential at a plurality of points and measuring the differences in potential at the points with a differential static amplifier. Alternatively, a fluxmeter for measuring the electric field vector directly can be used to sense changes in the magnitude and direction of the field. A line defined between two points or a plane defined by three noncolinear points in space can be made to coincide with an equipotential line or surface in space, respectively, by adjusting the relative positions of the points such that either the potential differences between the points or the field components sensed along the defined line or in the defined plane are zero.

Abstract: Conventional first and second Schuler tuned inertial platforms, that are physically displaced from each other by a predetermined distance, are employed in an inertial system to reduce navigation errors caused by the uncertainty in the earth's gravitational field. In addition to the two Schuler tuned platforms, a conventional velocity measuring instrument is employed to provide damping to the inertial system. The invention takes advantage of the fact that for a pair of ideal platforms if the relative velocity between them as displaced sensors can be measured with moderate accuracy then performance rivaling that obtainable with a gradiometer aided inertial platform can be achieved.

Abstract: In a helicopter a servo system connected to operate in parallel with the rotor blade pitch controlling linkages and also to receive autopilot generated signals directing maneuvers. The system limits the autopilot control over the blade pitch or position in the short term and permits full control over the long term.

Abstract: A method and apparatus for utilizing the earth's static electric field to tect and/or avoid orographic protrusions extending from the earth's surface, the invention particularly allows detection of electrostatic field disturbances caused by typical mountain contours at horizontal distances up to five times the height of the mountain contour causing the disturbances. The present method comprises measurement of the horizontal component of the static electric field existing in the earth's atmosphere, the attitude of the platform from which such measurement is taken being essentially held parallel to an "artificial horizon". Orographic protrusions, or terrain obstacles, can thus be detected by an increase in the measured value of the horizontal component of the atmospheric static electric field.

Abstract: The circuit derives a rate signal from an a.c. signal proportional to attitude displacement provided, for example, from the synchro pickoff of a vertical gyroscope or an inertial navigation system, the pickoff receiving power from the aircraft a.c. power supply. The a.c. attitude signal is passed through a first bandpass filter tuned to the frequency of the power supply. The a.c. power supply signal is passed through a second bandpass filter identical to the first whose output is used as the reference signal for first and second identical demodulation circuits which include first and second matched low pass filters respectively. The filtered a.c. attitude signal is applied to the first demodulator circuit and the filtered power supply signal is applied to the second. The output of the first demodulator circuit is applied to a line voltage compensator and the output from the second demodulator circuit is applied to a d.c.

Abstract: A control system exhibiting more than one system response characteristic depending on input signal parameters, and without requiring discrete switching of system components, is disclosed. At least one system input signal of varying frequency and amplitude is supplied to both high pass and low pass filters, the output of one of which is amplitude limited and additively combined with the output of the other filter to form a first intermediate control signal which is subtractively combined with the input signal to form a second intermediate control signal. The first and second intermediate control signals are passed through signal transfer elements having different signal transfer characteristics, and then combined to provide multimode response.

Abstract: A rocket powered escape vehicle is equipped with an electrostatic attitude ensing system which commands a rocket motor mounted in gimbals on the bottom of the vehicle to provide a vertically upward seeking escape from an aircraft independent of aircraft attitude.

Abstract: A gravity survey and aircraft guidance system comprises a pendulum clock mounted in an aircraft in level flight, having a pendulum bob with a signal sender mounted thereon. A signal receiver mounted in proxmity to the pendulum bob generates an electrical pulse at each pendulum swing. The pendulum swings in a plane having a component parallel to the east-west direction of spin of the Earth. The pendulum has a nominal oscillation frequency at a first aircraft speed with respect to the Earth's surface. The pendulum will have a second oscillation frequency at a second aircraft speed with respect to the Earth's surface due to the change in the Earth's spin-induced centrifugal force on the pendulum. Alternately, the pendulum will have a second oscillation frequency when the aircraft flies over a mass anomaly in the Earth's surface. A frequency discriminator connected to the signal receiver, generates a correction signal in response to changes in the oscillation frequency of the pendulum.