Abstract: An aircraft automatic trim system is operable during autopilot control to transfer trim from the elevators to the stabilizers. The thresholds for trim transfer are based on the ratio of elevator demand to available elevator control. Trim commands are produced responsive to this ratio exceeding an amplitude and time dependent limit.

Abstract: A pair of cold air driven tubines are mounted in-line with each turbine driving one of two coaxial drive shafts. Each drive shaft is independently supported and separate drive air is supplied to each turbine such that the direction and speed of rotation of each drive shaft is independently controlled. Exhaust air from the forward turbine vents through an exhaust cavity that surrounds the aft turbine. Inlet drive air to the aft turbine is supplied via air ducts formed through the center of struts which extend radially from the inlet of the aft turbine, through the exhaust cavity and to an inlet port external to the turbine housing.

Abstract: An aircraft gyro simulator is operable in a dynamic mode to produce simulated pitch, roll and azimuth signals as a function of control wheel commands, flight control system commands, control surface status and the stored equations of flight for the aircraft under test. In its manual mode, the simulator responds to manual control commands to individually vary pitch, roll or azimuth, thereby testing aircraft systems response. In addition, multiple channels of tracking gyro signals may be produced, with each channel having a manually controlled offset of one or more gyro signals to test aircraft employing multiple autopilot systems.

Abstract: Each of three redundant sensor sets (16, 18, 20) provides flight status data to a corresponding one of three flight control computers (22, 24, 26). Each of the computers shares sensor data as well as computed control surface command signals with all other system computers. The command signal outputs from two computers are transduced (34, 36) to mechanical commands which are combined and applied to the appropriate aircraft control surface. The remaining computer output is a mathematical model of the mechanical outputs of the other channels. Fault detection and isolation is accomplished by cross channel comparing sensor data, command signals, model/surface position information and by incorporating channel monitors for detecting generic or common mode flight control computer failures.

Abstract: A wing-mounted pod for preventing an unstable increase in the pitching moment of a swept-wing aircraft due to increasing speed and angle of attack is disclosed. This invention is for use on a swept-wing aircraft of the type having a nonlinear, unstable increase in its pitching moment due to a loss of lift at the outboard wing above a predetermined angle of attack at high Mach numbers. For an aircraft having a single, strut-mounted engine on each wing, the pod is placed along the intersection of the upper surface of the wing and the inboard side of the engine mounting strut. The pod prevents an increase in the pitching moment by inducing the formation of a shock in the air flowing over the upper surface of the inboard wing at the same angle of attack at which the outboard wing loses lift. The shock causes localized flow separation on the inboard wing, thereby preventing the increase in pitching moment otherwise experienced by the aircraft.

Abstract: A loudspeaker system includes a low-frequency driver and a high-frequency driver which are connected to a crossover network. The crossover network includes an inductor in series with the low-frequency driver for attenuating high-frequency signals at the crossover frequency and a capacitor in series with the high-frequency driver for attenuating low-frequency signals at the crossover frequency. An equalizer circuit connects between the high- and low-frequency drivers and operates to dampen resonant ringing which is otherwise produced. The equalizer circuit preferably comprises a series LRC circuit having a resonant frequency and a Q factor equal to the resonant frequency and Q factor of the circuit formed by the crossover network and drivers. The equalizer circuit is particularly suited for application in a disclosed loudspeaker system which utilizes a high inductance crossover inductor to enhance system bass response without sacrificing clarity.

Abstract: A power line monitor capable of monitoring multiple power lines simultaneously includes a channel circuit for each monitored line, a common logic circuit and control logic. The signal on each power line is analog-to-digital converted and stored in channel circuit memory. A trigger detector produces a trigger detect signal in response to the monitored signal exceeding a preset limit. The trigger detect signal initiates a delay time during which the conversion and storing process in the triggered channel continues. The delay time is selected such that a desired amount of both pre- and post trigger data is retained in the associated channel memory. The control logic is operable in either a manual or an automatic mode. In the manual mode, memory stored data in a triggered channel is repetitively cycled to a digital-to-analog converter provided in the common logic, whereby an operator can monitor the stored waveform and, if desired, load the channel memory contents to magnetic tape.

Abstract: Switches, manually operable to produce a desired logic signal level, are user assigned to represent the various variable inputs to a Boolean network. Indicators are user assigned to represent the logic state of outputs from the network. Process logic is user programmable to define the Boolean and sequential logic relationships between the assigned inputs and outputs. A visual display identifies to a user the input variable assigned to each switch and the logic output assigned to each indicator.A user may analyze the operation of the Boolean network being emulated by monitoring output indicator status in response to logic level inputs selected by the switches.

Abstract: A fuel gaging system of the type wherein the capacitance of a probe (20) within the fuel tank is used as an indication of fuel quantity via an assumed density/dielectric constant relationship (10) of the fuel. System accuracy is improved by directly measuring fuel density and dielectric constant. These values are compared with the assumed values in a processor (68) which generates an appropriate gaging correction signal in response to a discrepancy.

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: Aircraft roll command signals are generated as a function of the Microwave Landing System based azimuth, groundtrack, groundspeed and azimuth rate or range distance input parameters. On initial approach, roll command signals are inhibited until a minimum roll command requirement is met. As the aircraft approaches the centerline of the runway, the system reverts to a linear track control.

Abstract: A method for determining proper operation of a multi-section photo-sensitive detector (10) includes measuring (102) the cathode-anode dark resistance of each section and rejecting the detector (104, 108) if any section measures less than a predetermined value or if the ratio of the dark resistance of any section to the section having the highest dark resistance (106) exceeds a specified level. Each detector is also subjected to anode-to-anode or cathode-to-cathode dark resistance testing for both adjacent (110) and non-adjacent (124) sections, with testing based on comparisons between section pair readings and the sum of the cathode-anode dark resistances of each section in the tested pair (114, 128).

Abstract: An insert assembly includes a frustoconically shape cone nut (10), a cylindrical shell (20) and a bolt (36). The cone nut (10) has a longitudinal bore (12) which is tapped to accept the threads on the bolt. The shell (20) has projecting barbs (28) arranged in a helical pattern on the shell's outer surface. The assembly, comprising the bolt through the shell and threaded into the smaller diameter end of the nut cone, is driven into a bore in the work piece. The bolt is then rotated causing the cone nut to penetrate the shell resulting in radial expansion of the shell whereby the barbs become embedded in the work piece. A keying feature between the nut and the shell prevents nut rotation with the bolt.

Abstract: A latch for securing a panel within an overhead opening includes a base portion which is secured to the panel. A cam is pivotally mounted to the base and is biased such that upon insertion of the panel into the opening a foot on the cam snaps over adjoining structure, pinching the structure against the base and thereby securing the panel. A trigger mechanism pivotally mounts to the cam and is configured to lock the cam in an unlatched position upon desired removal of the panel.

Abstract: Flanges (12, 14) attached to duct sections mate to form a ribbed portion around the circumference of the ducts. A plurality of U-channel shaped sections (50, 52, 54) are placed over the ribbed portion with a band (40) holding the sections in place, thereby securing the coupling. Each U-channel section is formed of parallel side sections (20, 22) secured to a segment via shearable fasteners (26). A sufficient bending load to the ducts causes shearing of the fasteners thereby releasing the duct coupling.

Abstract: An autopilot control system includes roll rate synchronization circuitry for precisely responding to control wheel roll commands without overshoots. Unique fade-in/fade out circuitry prevents transient signal "bumps" upon mode switching of the system.

Abstract: An improved inner loop control is disclosed for use in an aircraft pitch axis control system. Signals representative of vertical acceleration and pitch rate are complementary filtered and summed to produce an "inner loop" damping signal which is combined with "outer loop" command signals to produce an elevator control signal. The improved approach provides higher outer loop control law gains and better system stability, resulting in higher control bandwidth and tighter command tracking, especially in turbulence.

Abstract: A pair of input sense signals are processed and passed to inputs of two servo amplifiers. The amplifier outputs are summed and converted to a corresponding hydraulic pressure in a T-valve. Transducers monitor the produced pressure and provide feedback signals to the servo amplifiers. A comparator compares the servo amplifier outputs and activates a warning device if the signal difference therebetween exceeds a threshold level. Equalizer circuitry processes the comparator output and provides correction signals to the servo amplifier inputs to wash-out offset effects.

Abstract: Disclosed is a vertical flight path angle steering system for aircraft, utilizing a digital flight control computer which processes pilot control inputs and aircraft response parameters into suitable elevator commands and control information for display to the pilot on a cathode ray tube. The system yields desirable airplane control handling qualities and responses as well as improvements in pilot workload and safety during airplane operation in the terminal area and under windshear conditions.

Abstract: An aircraft spoiler control system wherein each of a plurality of spoilers is driven by an electrically responsive actuator. Sense signals representative of the aircraft's control wheel rotation, speedbrake lever deflection, flap position and air/ground status are processed by logic which produces a corresponding control signal for each actuator. Fault detection circuitry switches in a back-up actuator control signal if a fault occurs in the active control circuit.