Abstract: In order to provide a magnetic tape recorder where the magnetic tape and tape reels are driven by a drive belt with the capability of operating in temperature extremes, the drive belt is composed of silicone rubber that has been cured with a peroxide curing agent.

Abstract: A digital symbol generator for developing analog deflection voltages to drive a cathode ray tube display forming a plurality of symbols from successive blanked and unblanked vectors rotatable about an arbitrary angle of rotation. Each vector is specified by a binary representation of its polar coordinates including vector angle and length, rotation being accomplished by digital addition of the vector angle and angle of rotation. A line length counter generates a pulse train the number of pulses of which is proportional to vector length and the frequency of which is greater for blanked vectors than for unblanked vectors so that blanked vectors are drawn at a faster rate. Symbol error checking is accomplished by a vector closure technique wherein the symbology end point is measured at the output of the symbol generator and compared with the independently calculated true end point.

Abstract: A reel-to-reel constant speed tape transducer in which the torques of the reel motors are controlled to maintain the tension in the tape to the take-up reel substantially equal to or slightly greater than the tension in the tape from the supply reel. The speed of the take-up reel provides a measure of reel diameter to generate signals which control the torque of the reel motors.

Abstract: A flexure in a force transducer, as an inertial guidance accelerometer, for securing a force sensitive element to a mounting base includes one or more flexure sections having one or more recessed surfaces which are substantially coincident with the neutral bending plane of the flexure. Electrically conductive coating on the recessed surfaces provide electrical connections to components located on the force sensitive element. The conductive coatings on or near the neutral bending plane of the flexure sections minimizes bending moments caused by stresses set up between the conductive coatings and the flexure which may in turn lead to bias errors. At the same time, the flexure configuration provides for the desired strength and spring rate for the force sensitive element.

Abstract: A flexure in a force transducer, as an inertial guidance accelerometer, for securing a force sensitive element to a mounting base includes one or more flexure sections having one or more recessed surfaces which are substantially coincident with the neutral bending plane of the flexure. Electrically conductive coating on the recessed surfaces provide electrical connections to components located on the force sensitive element. The conductive coatings on or near the neutral bending plane of the flexure sections minimizes bending moments caused by stresses set up between the conductive coatings and the flexure which may in turn lead to bias errors. At the same time, the flexure configuration provides for the desired strength and spring rate for the force sensitive element.

Abstract: The necessity for rigorously controlling process variables or making physical measurements is eliminated in a method of manufacturing a flexure for use in connecting a force sensing element to a mounting base in a force transducer where indicator portions are provided in a blank and material is removed uniformly from the blank including indicator portions until the indicator portions disappear. This process can also be used to configure a flexure out of a unitary piece of material such as fused quartz where a blank is masked except for indicator portions on each surface of the blank and at least one other surface portion; material is removed from the non-masked portions of the blank; and after removing the mask, material is removed from the blank until the indicator portions disappear.

Abstract: A digital data recorder has a microprocessor control which directs data to the read/write transducer and actuates the tape drive. The recorder accepts data in serial digital form and has an analog-to-digital converter-multiplexer which receives analog data and adapts it for digital recording. Data is read from the tape through an output connector to one of several retrieving devices. An identifying input to the microprocessor from the retrieving device provides for control of the read transducer and the tape drive to direct the appropriate data to the retrieving device.

Abstract: A weight and balance system for an aircraft or the like which measures the bend in a structural member of the aircraft, such as a landing gear element or a wing or fuselage section, by use of inclinometers mounted to the member and each having a signal output representing the angle of the member with respect to a reference plane and then summing signal outputs from the incinometers to determine the angle of the bend which provides an indication of weight. In one example, the landing gear of the aircraft includes a member which bends in response to aircraft weight and a pair of inclinometers, in the form of servoed accelerometers, are mounted to the member adjacent opposite ends thereof and each provide a voltage output representing the angle of the member relative to the reference plane, and a summing device for summing said signal outputs as an indication of weight.

Abstract: A charge amplifier having minimum offset voltage such as for use in processing a signal from a capacitive transducer. The amplifier is arranged to minimize the offset voltage and drift. The amplifier is arranged to be reset to zero upon application of supply voltage thereto, and the resetting circuit is arranged to reset the amplifier automatically during an adjustable interval after application of the supply voltage. The charge amplifier is further compensated for temperature variation and is arranged at minimum offset voltage notwithstanding strong background noise.The amplifier is arranged to have a drift of no more than a fraction of a millivolt per second. The amplifier circuit includes an improved switching arrangement and may utilize a second amplifier circuit for effecting temperature compensation.

Abstract: In an assembly, for use in transducer type instruments such as accelerometers, having a position sensing movable member including a pick-off element, wherein the movable member is secured to a support member by a flexure or hinge and the support member in turn is cantilevered between two stator members, instrument bias errors resulting from the securing of the non-cantilevered portion of the support member between the stator members can be reduced by aligning the edges of the surfaces of the stators that contact the support member with the centroid of the pick-off element so that the axis of cantilever rotation passes through the centroid of the pick-off area. In transducers having electrical leads on the movable member, the flexure and the support member for electrically connecting the pick-off element to the support member, bias errors can be further reduced by including the area of the electrical leads in calculating the centroid.

Abstract: In an aircraft excessive rate of descent warning system that utilizes barometric descent rate compared with aircraft altitude above ground to generate a warning, nuisance warnings at airports having terrain that slopes generally downwardly towards the runway can be substantially reduced by modifying either the descent rate signal or the altitude above ground signal as a function of radio altitude rate thereby having the effect of increasing the descent rate required to trigger a warning when the aircraft is descending essentially parallel to the ground.

Abstract: In order to facilitate construction of a compact, lightweight servoed accelerometer with capacitive pick-off, a one-piece support frame, adapted to be inserted within a cylindrical housing, is used to support a pair of capacitor plates and a lightweight longitudinally reinforced pendulum or seismic mass having a paddle on one end. The paddle is positioned midway between the capacitor plates, thereby forming a pair of capacitors each having a capacitance on the order of 2 to 4 picofarads. Attached to the pendulum is an axle which in turn is supported between two flexures by means of jeweled pivoted bearings. The ends of the flexures are rigidly secured to the support frame, and a desired pressure of the bearings against the axle is maintained by means of adjustment screws.

Abstract: A thermal switch having contacts with one contact being movably mounted on a carrier and with movement of the carrier controlled by a bimetal actuator disc. The actuating movement is transmitted through a striker pin of molded ceramic material which is fastened in fixed relation to the carrier by a layer of adhesive of controllable thickness to establish the effective length of the striker pin.The method of manufacturing the thermal switch embodies holding of the striker pin in fixed predetermined relation to components of the thermal switch. During movement of the parts to this position, a mass of adhesive carried at an end of the striker pin is pressed between the end of the striker pin and the carrier to provide lateral flow thereof until said pressing is discontinued to provide a controlled thickness layer of adhesive which is then set with the parts held in a predetermined relation.

Abstract: In order to reduce bias errors resulting from mounting of a force restoring coil assembly element of a force balancing transducer, the force coil assembly is suspended by means of one or more hinges from a force sensing movable member, which includes position pick-off means, that in turn is connected by hinging means to a support member. The effects of strain may further be reduced by locating the first hinges essentially along the axis of the centroid of the pick-off means.

Abstract: An improved capacitive pick-off circuit is provided by utilizing an operational amplifier wherein a pick-off capacitor to be measured forms a part of a feedback circuit of the operational amplifier resulting in the gain of the operational amplifier becoming inversely proportional to the capacitance or directly proportional to the gap between the plates of the capacitor thereby providing a measure of capacitance. A differential capacitive pick-off circuit is implemented by using a pair of operational amplifiers wherein feedback circuits controlling the gain of the operational amplifiers include pick-off capacitors to be measured and a third differential amplifier is connected to the outputs of the two operational amplifiers to provide a signal representing the difference in capacitance between the two pick-off capacitors.

Abstract: An improved capacitive pick-off circuit is provided by utilizing a reference current generator to apply a square wave to a pick-off capacitor and the resulting voltage across the capacitor is then applied to a fixed capacitor. The resulting fixed capacitor current then provides a measure of the capacitance of the pick-off capacitor. A differential capacitive pick-off circuit is provided by applying the reference current to each pick-off capacitor and providing a fixed capacitor for each of the pick-off capacitors. The resulting fixed capacitor currents are combined and the resulting differential current is used as a measure of the difference in capacitance or the difference in the gaps between the plates of the capacitors.

Abstract: A differential amplifying circuit eliminates the common mode component of a composite signal consisting of the common mode component and a differential component. Two differential amplifiers are coupled to a composite signal source so that one amplifier amplifies only the differential component and transfers the common mode component unchanged. The other amplifier processes the common mode component. The outputs of the differential amplifiers are connected to a voltage divider. The output of the circuit is taken from a tap on this voltage divider at a point where the common mode component is eliminated so that only the amplified differential component remains.

Abstract: A head-up visual approach instrument having a display of flight guidance information for a two-segment approach to touchdown. The display includes flight path indicia which the pilot aligns with an outside world aiming point, as the touchdown zone of a runway. During the first segment the flight path indicia is positioned as a function of aircraft altitude to define the changing sight angle to the target.

Abstract: Direct readings of the timing angle and duration of the fuel injection of a diesel engine along with the engine speed are provided by an electronic test instrument that converts the duration of the timing advance and the duration of one engine revolution into electrical pulses of corresponding width. Both these pulse widths are then converted to corresponding electrical quantities and the quantity which corresponds to the timing angle is divided by the quantity which corresponds to one engine revolution to produce an indication of timing angle, or alternatively a constant reference quantity is divided by the quantity which corresponds to the engine revolution, thus providing an indication the engine speed.

Abstract: A one-piece support frame is used to support a pair of capacitor plates and a lightweight longitudinally reinforced pendulum having a paddle on one end. The paddle is positioned midway between the capacitor plates forming a pair of capacitors. Attached to the pendulum is an axle which in turn is supported between two flexures by means of jeweled pivoted bearings. The ends of the flexures are rigidly secured to the support frame, and a desired pressure of the bearings against the axle is maintained by means of adjustment screws. Also attached to the pendulum is a torque coil which interacts with a magnetic assembly, secured to the support frame, to restore the paddle to the midpoint between the capacitor plates when the pendulum has been subjected to an acceleration force.