Abstract: A method and apparatus for simulating a windshear. A vortex is modelled in terms of a family of concentric streamlines and the position of an aircraft is defined with respect to the vortex as the aircraft traverses a reference plane. Four or more vortices are used to generate streamlines which match those encountered in an actual microburst. Each vortex placed above the simulated ground level is matched by a vortex of equal strength but opposite rotation placed below the simulated ground level at a distance equal but opposite to the height of the vortex above the ground. Strengths, distance from the vortex center, and height of the vortex may be programmed by the user. The high degree of flexibility permits accurate reproduction of the winds generated by actual microbursts for testing and developing microburst detection devices.

Abstract: A flight path control apparatus for controlling an aircraft to execute a capture maneuver of a predetermined heading or track and provide a roll correction signal for controlling the path of said aircraft along an exponential transition curve. The corrective heading or track signal .DELTA..psi. is generated in accordance with ##EQU1## where .DELTA..psi. is the magnitude of the corrective heading or track command signal,g is a constant corresponding to the acceleration of gravity,V.sub.t is the true airspeed of the aircraft,.tau. is a predetermined constant of aircraft roll rate,.phi..sub.i is the roll angle of the aircraft at the initiation of the capture maneuver,.phi..sub.i is the time rate of change of the roll angle of the aircraft at initiation of the capture maneuver, and.phi..sub.M is a predetermined maximum time rate of change of roll rate of the aircraft during the capture maneuver.

Abstract: A DC-to-DC power converter topology utilizing parallel connected transformers in a buck switching configuration with each stage operated 180.degree. out-of-phase, with the primary windings of the transformers sequentially feeding into a common filter capacitor. On each transformer, a secondary winding is switched to a load at the time the primary winding is shunted across the filter capacitor. The circuit provides dual inductor buck power stage operation while maintaining input-output isolation. Interleaved power processing provides continuous capacitance support for the output voltage produced by the power supply.

Abstract: An optical switch for coupling one of a plurality of input light sources to one of a plurality of output terminals is comprised of a Bragg cell array acoustically excited in accordance with one or more preselected control frequencies from a selectable source of such frequencies. The beam deflection is proportional to the applied radio frequency. A scan lens is positioned to intercept the deflected beams and to focus the beams into a plane for imaging upon a linear array of optical output fibers. By choice of the control frequency any combination of input and output fiber optic lines may be optically coupled without requiring active sensors. Sufficient diffraction is provided by the Bragg cell in combination with the scan lens to minimize cross-talk and insertion loss.

Abstract: Apparatus for guiding an aircraft along the center line of a runway at rollout touchdown. A rollout predict path command is generated in accordance with a first path segmentY.sub.1 =T.sub.1 (Y.sub.m +Y.sub.u)(1-e.sup.-t /Ti)-Y.sub.m t+Y.sub.ion engaging rollout mode, which path segment transitions to a second path segmentY.sub.2 =Y.sub.1 e.sup.- (t-to/T.sub.1)at a given elapsed time t.sub.o, where T.sub.1 is a predetermined time constant, Y.sub.i is an initial value of lateral displacement on rollout engagement, Y.sub.i is the time derivatives threeof, Y.sub.M is a predetermined maximum lateral displacement rate, and t is the elapsed time. The predict path command signal is combined with a rate signal derived from a localizer position estimate to produce an error signal for commanding a rudder deflection to align the aircraft with the center line of the runway.

Abstract: An electromagnetic deflection display system is operative for bi-directional raster and stroke deflection and provides minimum power dissipation in raster mode during a segmented or patch raster display. Energy stored in the deflection yoke during one direction of the raster scan is returned to an energizing power supply during the subsequent return scan in a manner that conserves power while avoiding an over-voltage condition of the associated power supply. A transformer is coupled to receive a portion of the energy stored in the yoke and return it to a designated raster mode power supply. The raster mode return voltage may be determined independently of stroke mode power requirements so as to optimize raster power savings and ampifier raster performance independent of the optimum stroke voltages.

Abstract: An interactive trainer for electronic countermeasures simulation capable of providing displays of in-flight threats and countermeasures responses representative of an actual combat equipment suite. Threat scenarios are stored in computer memory and recalled at a push-button display console. Default parameters may readily be modified by the operator under software control. The aircraft position with respect to selected threats is displayed in real time superposed on the threat parameters. Displays are identical to that provided by the equipment simulated and reflect the true operational status as preset by the operator.

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 voltage regulator particularly adapted to A.C. distributed power systems requiring independent voltage regulation at a plurality of frequency responsive power supply modules energized by a power source at a common alternating frequency is provided by resonant tuning of the regulator circuit. An LC resonant circuit determines the operating frequency of the regulator, and may be operated above or below the excitation frequency. The output voltage is applied to a current amplifier which energizes a linearly variable inductor in accordance with the sensed D.C. output voltage. Changes in the output voltage result in changes in the tuned frequency of the LC circuit and the corresponding corrective change in the output voltage. Circuits providing both voltage and current regulation are described.

Abstract: A regulator circuit for equalizing the load currents of a plurality of power supply modules connected in common to feed a common load. Each of the modules includes a pulse-width modulator for adjusting the duty cycle of the module, thereby to adjust the voltage regulation point and corresponding current output of the module. A current sensor produces a current level signal proportional to the current output of the module. The current level signal is applied through a current amplifier to generate a corresponding variable error voltage. A fixed reference voltage derived from the output voltage and the variable error voltage are applied to the pulse-width modulator to vary the duty cycle so as to produce a decrease in load voltage with an increase in current output and an increase in the load voltage with a decrease in current output thereby equalizing the current output of the module with modules having substantially equal output voltages.

Abstract: A gyroscopic rate sensor has a motor driven shaft on which is mounted a flexible disc rotor enclosed in a gas-filled housing with a rotating rigid plate, also mounted on the shaft, to provide viscous gaseous restraint. A rotating capacitive plate assembly referenced to the drive motor spin axis provides a stable electrical output signal proportional to periodic deflections of the disc rotor. By perforating the disc rotor near the spin axis, spring restraint is minimized while the squeeze film damping provides improved dynamic response.

Abstract: A target for use in ion beam sputtering is arranged for varying the chemical composition of the deposited film without requiring substantial fabrication of a new target. The target is comprised of a disc having therein a plurality of openings which extend only part way through the disc. The target is fabricated from a predetermined chemical composition similar to that desired to be deposited. The openings within the target are filled with plugs of a varied chemical composition. By choice of the number of plugs and their composition, as well as the size of the plug, the structure of the film may readily be varied to a small degree or a large degree. The invention is applicable to all methods of deposition that use a target as a source of material for the film.

Abstract: An aircraft guidance system for flying an optimal inertial flight path in a windshear encounter. Zero inertial flight path angle command is utilized as the basis for guidance commands for either horizontal or vertical windshears; the flight path angle command is constant regardless of the actual magnitude of the shear. The effect of the guidance law described is to provide a zero inertial flight path angle to prolong excitation of the aircraft's phugoid oscillatory mode. By utilizing inertial flight path angle derived from an inertial reference system, errors introduced by vertical gyroscope systems are eliminated and thus a very accurate flight path angle guidance law is produced. The described guidance control law maximizes the aircraft's time in the air during a windshear encounter. Protection against aircraft stall is also provided by using a computed variable maximum allowable angle of attack.

Abstract: A clutch/damper for isolating and absorbing vibration induced reactive torques from adversely affecting a motor drive system. A friction plate variably engages a gear coupled to the drive motor and to a load mass to permit normal drive in the absence of excessive reactive torque forces and to allow the motor to continue to drive against a slipping load in the presence of excessive reactive torque forces. Feedback is employed in the drive system to compensate for the small errors induced by the slippage.

Abstract: An optical waveguide for transmitting light energy is defined by a glass capillary with a core of noncentrosymmetric non-linear optical polymer which has been poled to induce a stable axial alignment of molecules therein. Changes in refractive index of the polymer are induced by an applied electric field. In a preferred embodiment, the waveguide is used as an electric field sensor and may form an arm of a Mach-Zender interferometer. The device is adapted to modulate waveguided electromagnetic energy by a change in refractive index proportional to the applied electric field. In a further embodiment, the birefringent properties of the polymer are used to cause polarized light energy transmitted by the waveguide to undergo a change in polarization, which, when intercepted by a polarization sensitive analyzer, provides an amplitude modulation of the transmitted light energy.

Abstract: An apparatus for reading a first addressable memory and writing into a second addressable memory wherein the first addressable memory is logically arranged in a rectangular matrix and is scanned at an arbitrary angle with respect to the matrix for producing a plurality of scan patterns whose parameters can be altered and controlled by an external source, while the second addressable memory, also arranged in a rectangular matrix, is written into along parallel rows and columns. The apparatus is particularly adapted for use with a digital map display system having an airborne computer for generation the scan parameters.

Abstract: A circuit for a differential amplifier having common mode rejection means. The common mode voltage is applied to an inverting amplifier to derive a common mode signal in opposition to the applied common mode voltage. A portion of the applied common mode voltage is combined with the opposing common mode voltage in a ratio such that the resultant common mode signal has a null value. A voltage divider network coupled to the input of the amplifier provides an output corresponding to a differential signal and substantially independent of the common mode signal. Buffer amplifiers provide substantial isolation from stray capacitances and loading by the resistor elements, thereby enhancing the bandwidth of the circuit.

Abstract: A digital mapping display system for an aircraft wherein map data from a mass memory unit is periodically loaded into RAM in the form of a cache memory in accordance with the aircraft trajectory. The cache memory is randomly addressable within the physical address space of a control processor, individual segments of the cache memory being loaded with map data and updated while other segments are being displayed, thereby avoiding the inherent delay of accessing the mass memory unit and addressing the entire RAM array. Parallel processing of map data and symbology facilitate a real-time display.

Abstract: An aircraft guidance system for optimizing the flight path of an aircraft in the presence of a windshear maximizes the time the aircraft remains in the air and the distance traveled regardless of the magnitude of the windshear, in the presence of horizontal or vertical windshear components, while effectively minimizing excitation of the aircraft's phugoid mode. A flight path angle is commanded sufficient to clear any obstacle that may be found in the airport vicinity. For longitudinal or horizontal shears, a slightly positive constant flight path angle which is a function of the magnitude of the vertical wind is added to the slightly positive flight path angle command to produce a modified command that compensates for the decrease in flight path angle relative to the ground caused by the vertical wind. The system inhibits exceeding stick shaker angle of attack by reducing the command signal until the actual angle of attack is equal to or less than the stick shaker angle of attack.

Abstract: An improved windshear warning apparatus for aircraft, responsive to both the magnitude of the wind shear and the allowable time the windshear can be tolerated at a given magnitude. The sensed magnitude is used to compute the allowable time before providing a windshear alarm. For large windshear rates, the allowable time is short; conversely for small windshear rates which exceed a threshold level, a longer time period is computed before an alarm occurs. Since a windshear rate must persist for the computed allowable time before activating the alarm, windshear rates that are above the threshold level for elapsed time less than the computed allowable time will not result in an enunciation, while high magnitude windshear rates of short duration will not cause false alarms since they do not exceed the computed allowable time.