Abstract: A system and method of increasing the control authority of redundant stability and control augmentation system (SCAS) actuators by utilizing feedback between systems such that one system may compensate for the position of a failed actuator of the other system. Each system uses an appropriate combination of reliable and unreliable inputs such that unreliable inputs cannot inappropriately utilize the increased authority. Each system may reconfigure itself when the other system actuator fails at certain positions so that the pilot or other upstream input maintains sufficient control authority of the aircraft.

Abstract: A system and method of increasing the control authority of redundant stability and control augmentation system (SCAS) actuators by utilizing feedback between systems such that one system may compensate for the position of a failed actuator of the other system. Each system uses an appropriate combination of reliable and unreliable inputs such that unreliable inputs cannot inappropriately utilize the increased authority. Each system may reconfigure itself when the other system actuator fails at certain positions so that the pilot or other upstream input maintains sufficient control authority of the aircraft.

Abstract: A rotorcraft autopilot system includes a series actuator connecting a cockpit control component to a swashplate of a rotorcraft, the series actuator to modify a control input from the cockpit control component to the swashplate through a downstream control component. The rotorcraft autopilot system also includes a differential friction system connected to the cockpit control component, the differential friction system to control the series actuator to automatically adjust a position of the cockpit control component during rotorcraft flight based, in part, on a flight mode of the rotorcraft.

Abstract: A method of increasing the control authority of redundant stability and control augmentation system (SCAS) actuators by utilizing feedback between systems such that one system may compensate for the position of a failed actuator of the other system. Each system uses an appropriate combination of reliable and unreliable inputs such that unreliable inputs cannot inappropriately utilize the increased authority. Each system may reconfigure itself when the other system actuator fails at certain positions so that the pilot or other upstream input maintains sufficient control authority of the aircraft.

Abstract: A rotorcraft autopilot system includes a series actuator connecting a cockpit control component to a swashplate of a rotorcraft, the series actuator to modify a control input from the cockpit control component to the swashplate through a downstream control component. The rotorcraft autopilot system also includes a differential friction system connected to the cockpit control component, the differential friction system to control the series actuator to automatically adjust a position of the cockpit control component during rotorcraft flight based, in part, on a flight mode of the rotorcraft.

Abstract: A method of increasing the control authority of redundant stability and control augmentation system (SCAS) actuators by utilizing feedback between systems such that one system may compensate for the position of a failed actuator of the other system. Each system uses an appropriate combination of reliable and unreliable inputs such that unreliable inputs cannot inappropriately utilize the increased authority. Each system may reconfigure itself when the other system actuator fails at certain positions so that the pilot or other upstream input maintains sufficient control authority of the aircraft.

Abstract: A control system for providing individual blade control inputs to a four-bladed helicopter rotor. Limited authority series actuators located in a non-rotating portion of the helicopter are driven by a computer which receives inputs from individual blade sensors and aircraft stabilization sensors, summed with cockpit control inputs, and the resultant motions transmitted to the rotor blades through a conventional swashplate which drives four blades of the rotor and a translatable differential sleeve and summing linkage which drives only two blades. The differential sleeve is adapted for axially raising or lowering the swashplate. The combined motion of swashplate and differential sleeve is shown mathematically to result in individual blade control in pitch. Computer individual blade commands are converted from the rotating reference frame to cyclic, collective and differential blade pitch commands in the fixed reference frame through a coordinate transformation matrix.

Abstract: A flexible tube of uniform internal diameter extends through a peristaltic pump and has its inlet communicating with a supply of liquid to be sampled. The pump is cyclically operated first in a reverse direction to purge all liquid from the tube, and then in a forward direction to pump liquid from the supply to a collector. When the pumped liquid fills a first portion of the tube for a predetermined axial distance from its inlet, a device disposed externally of the tube senses the presence of the liquid and signals a processor, which then determines the rate of flow of the liquid, and the total time T.sub.t the pump must operate to fill the entire tube plus a desired sample volume. The cycle is completed by momentarily reversing the pump to purge the first portion of the tube, and then it is operated in its forward direction for the time T.sub.t.

Abstract: During a transition of a VTOL aircraft such as a helicopter, from one altitude held without its ground effect zone to another to be held within its ground effect zone, or vice versa, a collective stick position synchronizer which can memorize the proper trim condition at the previous altitude in conjunction with the stick force sensor out-of-detent logic and a low vertical speed sensor, together constituting a ground effect zone detector, is used to drive the collective stick trim actuator in a direction which relieves any force being exerted by the pilot in order to maintain the new commanded altitude.

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 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 altitude preselect apparatus for use with or incorporation into an automatic flight control system combines the incremental altitude signal from a pneumatic encoding altimeter with a vertical speed computation to generate a smooth, continuous instantaneous altitude signal. A vertical speed reference signal is generated to control the vertical flight path of the aircraft when the instantaneous altitude reaches a prescribed proximity to a desired flying altitude which is manually selected by the pilot. The apparatus initiates a capture sequence to hold the aircraft at the desired altitude once it is reached.

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: Strapdown, multifunction actuator apparatus comprising one or two integral units adapted for installation in an aircraft, particularly a helicopter, and coupled between the pilot's control stick linkage and the aircraft control surface (or surface servo boost) linkage to perform the functions of series actuation, trim actuation, artificial feel, control position sensing, and control authority limits. The apparatus includes a series actuator installed in the vehicle and connected to the vehicle control linkages in the conventional parallel actuator manner; that is, it is secured directly or strapped down to the airframe and therefore greatly simplifies control system installation and reduces problems such as those associated with control rod vibration resonances normally encountered with conventional integral-with-linkage series actuator installations.

Abstract: A single actuator unit is installed in an aircraft, for example, a helicopter, and is coupled to the control linkage from the pilot's stick to perform the functions of series actuation, trim actuation, artificial feel, control position sensing, control limits and, if needed, force boost. Although the device performs as a series actuator, it is installed in and connected to the vehicle surface control linkages in the conventional parallel actuator manner and therefore greatly simplifies control system installation and reduces problems associated with control rod vibration resonances normally encountered with series actuator installations.

Abstract: A flight control system utilizing a limited authority stability augmentation system having a long term attitude and/or path control input to enhance the automatic flight capability of the stability augmentation system. A position sensor coupled with the limited authority stability augmentation actuator provides an indication to the human pilot via a suitable indicator when the actuator is near or at the limit of its authority thereby permitting the human pilot to effect manual trim, thus recentering the actuator.

Abstract: A force feel system for an aircraft having a control member or stick connected to a boost actuator for positioning an aircraft control surface and a variable force gradient spring mechanism for providing a feedback of artificial forces to the control stick, and which includes non-linear or irreversible linkage apparatus coupled between the stick and the variable force gradient spring such that the force feel system does not require the implementation of monitoring or redundant systems to provide fail safe operation in the event of failure of said force feel system. In addition, the "hands off" stability of the aircraft is not affected by the system because in this "hands off" mode of operation the non-linear linkage apparatus prevents the force actuator from moving the control stick out of the trim position.

Abstract: An apparatus for extracting signals, proportional to data relative to a given variable, from two data modulated signals which mutually define the variable. Each signal is followed-up with a linear integrate/clamp circuit, the outputs of which are cross multiplied with the input signals. The multiplier output signals are summed and appropriately shaped to provide an output signal that is proportional to the desired angular rate.