Abstract: The operation of an actuator (16) is monitored by comparing its position (21) with the position (31, 136) indicated by a model which integrates (45, 135) a limited amount of the difference between the position command (24) applied to the actuator and the achieved model position (31, 136), the limited amount being variable (63, 67, 124) from a nominal limit (61, 65, 124) in dependence upon limited functions (74, 90, 114, 116) of the difference (33, 109) between the actuator position and the model position, and additionally reduced (80, 94, 122) when pilot input overrides (50, 108) the position of the actuator.

Abstract: A system which provides feel-force to the control stick of an aircraft by means of hydraulic pressure is provided with non-nulling, proportional, direct feedback loop, and a limited integral feedback loop in the drive of the pressure control servo valve that commands the pressure-generating hydraulic force actuator. Static nulls are compensated in the integral path; integration is corrected when the static null and integral output exceed a limiting value. Embodiments include software and/or hardware portions.

Abstract: In a system which provides feel-force to the control stick of an aircraft by means of hydraulic pressure, a fault indicating system which responds to excessive differences between desired and actual force in the actuator, only of a polarity in the same direction as concurrent stick motion, to separate pilot induced pressure excesses from force-system faults, is provided with directional sensitivity in the fault-indicating output logic. Excessive pressure errors in either direction of stick travel institute the monitoring of changes in stick position. Changes in stick position of an excessive magnitude are recognized as fault only if they occur in the same direction as the direction of excessive pressure error. A simple analog embodiment utilizes threshold detectors and a track store device; a dedicated-digital embodiment utilizes comparators, registers and a subtractor; and a computer embodiment utilizes a software routine.

Abstract: Natural gas taken from a gas well is loaded continuously and at a preselected, generally uniform rate into a movable separate pressure vessel means until such is filled with a discrete batch of natural gas at a pressure in excess of 800 psia, whereupon it is replaced with another separate pressure vessel means, with no interruption of gas flow. The filled, movable vessel means is then transported to an off-loading terminal. Well shock is thus controlled, and maximum natural gas recovery obtained. A generally uniform flow rate is obtained by a regulating valve, when well head pressure exceeds about 800 psia, and by a compressor when the well head pressure is below such value.

Abstract: Natural gas from one or more wells is gathered, dehydrated, compressed to a relatively high pressure, and loaded into pressure vessel means mounted for transporting at ambient temperatures by a transport vehicle. The pressure vessel means is then driven to a transmission pipeline terminal, or other end user, and the natural gas is off-loaded while being heated to prevent the formation of harmful hydrates, the gas being metered before flowing into the pipeline.

Abstract: In a helicopter, a pilot-actuated lever controls, through linkage mechanisms, a servo valve to drive a hydraulic piston; the piston moves a swash plate which in turn controls movement of rotor blade pitch positioning mechanisms against the force of blade loading, caused by aerodynamic forces. Blade loading, heretofore monitored visually by the pilot on a cruise guide indicator instrument, is used herein to control a secondary input to the servo valve, thereby to alter the position linkage mechanism which causes the force of a spring attached thereto to impose a force on the collective pitch control for blade loadings in excess of one-third of maximum allowable blade loads, in a direction tending to drive the control to lower collective pitch (lower blade loading). This provides "feel" to the pilot in proportion to blade loading when at critical magnitudes.