Abstract: An electrical indicator for providing a digital display representation of the value of an input variable has four display areas, each area being arranged to display an individual one of the digits of a four digit number representative of the value of the input variable. Each display area is in the form of a matrix array of light-emitting diodes. The indicator includes a computing unit which is arranged to energize those diodes making up each digit and, by varying the energization, to cause displacement of the least-significant digit within its display area upon change in value of the input variable. Digits within the other areas remain stationary until an adjacent less-significant digit is moved between `0` and `9` when the more-significant digit is displaced in synchronism with the less-significant digit. The computing unit includes a store which contains information as to which diodes should be energized to represent any particular digit.

Abstract: An electrical indicator has a consecutive series of light-emitting diodes which are arranged along a straight or curved reference scale. A limited region of the series, comprising several diodes, is energized and this illuminated region is displaced along the scale upon change in an electrical input variable supplied to the indicator such that the position of the region provides an analogue indication of the value of the input variable. To improve the appearance of the display and reduce power consumption, the brightness of the region varies along its length with one or both of the outermost diodes being energized at lower levels than another of the diodes. The indicator may include a shift register having a number of storage locations, each for storing signals representative of a corresponding one of the light-emitting diodes, the signals at these locations being displaced in accordance with change in value of the input variable.

Abstract: A control system for controlling displacement of the aerodynamic control-surfaces of an aircraft includes a first signal processor that is supplied with input signals from the pilot's control column and also with predominantly lower-frequency components of feedback signals derived in accordance with the actual position of the control surfaces. The first signal processor derives an intermediate signal from the input and feedback signal components by digital processing and supplies this intermediate signal to a second signal processor which also receives the predominantly higher-frequency components of the feedback signal. The second signal processor derives an output signal from the intermediate and feedback signal components by analogue processing and supplies this to an actuator for controlling displacement of the control-surfaces. The second signal processor may also receive additional feedback signals directly from the actuator.

Abstract: A probe assembly for measuring the speed of rotation of a gas-turbine engine compressor shaft has a sensor head mounted at one end of a tubular probe body by means of a bellows unit which permits limited axial displacement of the sensor head relative to the probe body. The sensor head has a sleeve sealed to its rear end, one end of the bellows unit being sealed to the sleeve and the other end being sealed to the probe body. The forward end of the probe body extends through the bellows unit and into the sleeve where it is resiliently coupled with the sensor head by a helical spring. Four outwardly inclined leaf springs are mounted on the end of the probe body within the sleeve and are resiliently urged against the inner surface of the sleeve so that they are free to slide over the surface of the sleeve while separation of the sensor head from the probe body is limited by engagement of the springs with an inwardly projecting lip on the sleeve.

Abstract: A display apparatus for displaying a plurality of physical parameters has a plurality of electrically-operable display regions which are to be operated in accordance with respective physical parameters. The display regions each comprise a plurality of display sections disposed in spaced array, an electrode which is common to all display sections in that display region, and a plurality of individual electrodes associated with individual and respective ones of the display sections in that display region. The electrodes of the said plurality of individual electrodes associated with one display region are coupled to respective ones of the said plurality of individual electrodes associated with another display region to form respective groups of electrodes.

Abstract: Display apparatus for displaying the magnitude of a physical parameter includes a plurality of display regions each of which contains a plurality of electrically-operable display sections. The display apparatus also includes an electric circuit means responsive to an electric signal representative of the said magnitude which is arranged to operate the display sections in a cyclic manner in accordance with that magnitude. To this end, the electric circuit means is arranged, during a first period of each cycle, to effect operation of any display regions in which all sections therein require to be operated and, during a second period of each cycle, to effect appropriate operation of any other display region in which only at least one of the display sections thereof require to be operated.

Abstract: A fibre-optic cable has a bundle of glass-fibre or silica-fibre strands extending along its length, each end of the fibre-bundle being sealed in a metal ferrule. A sheath of woven glass-fibre or silica-fibre extends about the fibre-bundle and is secured at each end to a respective ferrule in tension, such that the sheath is constricted onto the fibre-bundle along its length. The cable has an outer convoluted metal shell which is sealed at each end to a respective ferrule. A sleeve of elastic material extends around the fibre-bundle and the sheath, within the outer shell, and serves to support and cushion the fibre-bundle along its length. The sleeve may be of a woven fibre including glass-fibre or silica-fibre, and asbestos-fibre, or the sleeve may be of an elastomeric substance. A metal braid sleeve covers the outer surface of the convoluted metal shell. The cable may be included in a radiation pyrometer to transmit radiation to a radiation sensor.

Abstract: An optical waveguide coupling comprises a connector having a longitudinal bore and a pair of optical waveguides, for example, optical fibres, whose ends are disposed in opposite ends of the longitudinal bore with the waveguide ends optically coupled to one another. The connector comprises a generally tubular body and a multiplicity of flexible elongate members mounted on the tubular body and extending longitudinally therethrough to define the longitudinal bore, the elongate members being spaced apart around the tubular body and being individually displaceable towards the tubular body. The flexible elongate members are displaced towards the tubular body by the ends of the optical waveguides and resiliently engage the ends of the optical waveguides to maintain them in alignment with one another.

Abstract: A terminal for an optical waveguide includes a connector having a longitudinal bore in which an end of an optical waveguide is to be anchored, lens means for transmitting light from one end of the waveguide and defining a recess including a focal point of the lens means, and a housing in which the connector and lens means are mounted. The terminal also includes an elongate optical member having first and second ends with respective end faces, the first end of the elongate optical member extending partially through the connector and being anchored therein, and the second end of the elongate optical member being mounted in the recess in the lens means with its end face disposed at the focal point of the lens means. The connector includes means for maintaining the first end of the optical member and an end of an optical waveguide in alignment with one another.

Abstract: A surface-discharge igniter is formed by positioning a tubular assembly coaxially within the outer shell of a nose portion of the igniter. The assembly is welded about one end to form a seal with the outer shell, and glass material is placed within the assembly to form a seal with a central rod-shape electrode extending coaxially within the assembly. The assembly has an outer tube of the same material as the outer shell, and an inner tube which extends coaxially within the outer tube and which is of a different material, having a coefficient of thermal expansion substantially the same as that of the glass material. The inner tube is joined to the outer tube at an end remote from the seal with the outer shell. The nose portion forms the operative tip of the igniter and is welded to a rear body portion having screw threads for mounting the igniter and for making electrical connection to it.

Abstract: A fibre-optic cable includes a fibre-bundle, for transmitting light along the cable, that is sealed at either end to a metal ferrule. Each end of the fibre-bundle projects a short distance from its respective ferrule and is enclosed by a metal collar which is welded to the ferrule. The projecting ends of the fibre-bundle are sealed to the ferrules by melting a glass tube within each collar about the ends of the fibre-bundle. A thread of glass or Silastomer material extends between the two ferrules and is helically wound about the fibre-bundle so as to hold together the fibres of the fibre-bundle. Convoluted outer metal tubing extends about the fibre-bundle and is welded at each end to respective ferrules. The fibre-bundle is cushioned within the outer tubing by a sleeve of woven fibre which also extends between the two ferrules about the fibre-bundle and the helical thread.

Abstract: A reboiler for dehydrating di- or tri- ethylene glycol comprises a cylindrical, horizontal axis tank having a ceramic packed still column rising from its top near one end and a single U shaped fire tube extending longitudinally from the front end of the tank interiorly thereof toward its back end. Wet glycol is admitted to the base of the still column above a half tray and overflows into a catch pipe which drains into the front end of the tank. Dry glycol is taken off through an outlet at the bottom rear of the tank. Dry gas is admitted to the reboiler through a sparging pipe extending longitudinally of the tank from near the back end of the fire tube and then over the outlet to near the back end of the tank. A box shaped trough extending under and about the pipe separates the glycol adjacent the sparging pipe from an in-tank reservoir located below the pipe formed by a divider plate located near the front end of the pipe.

Abstract: An aircraft-speed indicating instrument has an index which is movable against a scale to provide a reading of airspeed, and a digital indicator which is selectively operable to provide a digital reading of either Mach number or the airspeed. The index and the digital indicator are driven by respective control systems supplied with a multiplexed electrical signal containing information representative of both Mach number and airspeed. Each control system includes gating means which is operable to pass only those parts of the multiplexed signal necessary for the associated control means to provde the desired reading.

Abstract: A head-up display system for an aircraft has a display unit which projects a display of symbology representing the aircraft flight parameters onto a separately mounted partially-transparent reflector positioned in front of the aircraft pilot, so that the pilot sees an image of the display against the external scene. The display unit has a sensor which receives an image of the display via the reflector. The sensor responds to displacement of this image from a reference established with respect to the display unit, caused by movement of the reflector relative to the display unit, and the display is correspondingly modified to compensate for such movement. The display unit may include a cathode-ray tube for providing the display which can be modified by adjustment of the deflection of the cathode-ray beam. In this case the reference established with respect to the display unit may be an instantaneous point image of the cathode-ray beam.

Abstract: A pressure transducer has a capsule having two chambers separated from one another by a diaphragm. The capsule is made entirely of a glass-ceramics material, such as, lithium alumino silicate. One of the chambers is sealed and has a lens with a curved surface adjacent the diaphragm such that, when the capsule is illuminated, a Newton's Rings pattern is produced by interference between light reflected from the surface of the lens and the diaphragm. Pressure is communicated to the other chamber so as to cause the diaphragm to be deflected into or out of the sealed chamber with a consequent shift in the interference pattern which is used to provide a measure of the pressure change. The capsule also has two further chambers which are identical to the first two chambers and which are both sealed. One of these further chambers is illuminated to produce a second interference pattern.

Abstract: The spiral grooving of a thrust-plate of an aerodynamic gas-lubricated bearing is formed by ionic bombardment of a flat face of a machined blank. The face is masked to leave exposed only those areas where material is to be removed. Grooving on a cylindrical surface of a spindle is similarly formed, the cylindrical blank being rotated to present the unmasked areas successively and repeatedly for bombardment.

Abstract: An indicating instrument particularly for use in a vehicle comprises a first element which is moved behind a window of the instrument such that the amount of the first element visible in the window is indicative of the distance travelled by the vehicle, and a second element that is moved in dependence upon the speed of the vehicle and such that the second element is obscured from view in the window by the first element while a predetermined relationship exists between the speed and distance.

Abstract: A fluid pressure supply apparatus includes a fluid pressure source, a fluid supply circuit to receive fluid under pressure from the fluid pressure source, and a fluid return circuit. These circuits are to be coupled to an hydraulic motor through first and second fluid paths. The supply apparatus further includes first means to couple the fluid supply circuit to the first fluid path to cause the hydraulic motor to be operated by the fluid pressure in a predetermined sense, and second means simultaneously to couple the second fluid path either to the fluid supply circuit, to provide a regenerative coupling for the motor, or to a fluid return path. This latter coupling is initially to the second fluid path, the second means being arranged to transfer that coupling from the fluid supply circuit to the fluid return path during operation of the motor in the predetermined sense.

Abstract: A graphics generator responds to signals defining a pattern to be displayed. The pattern comprises a plurality of pattern segments each of which may be a vector, conic or alpha numeric character. The graphics generator produces digital signals which are capable of driving a display through an A/D converter to produce a visual representation of the desired pattern segment. The pattern segment is broken up into a plurality of strokes of constant length regardless of orientation. Chaining the strokes on the display thus produces the desired pattern. An input signal defining a vector defines both the length and the orientation of the vector and these quantities are stored in length and orientation registers, respectively. The orientation signal is employed as an address into a sine/cos memory to derive stroke components in an orthogonal coordinate system which are then added to a beginning position of the stroke to produce the stroke end point.

Abstract: A push-button mechanism for tuning a radio receiver includes push-buttons that are actuable to rotate a turrent tuner to different extents for station selection. The side of each push-button contacts one end of an individual lever to pivot it through a predetermined angle upon actuation of the push-button. The other end of the lever contacts one of several projections on a bar which extends transversely of the push-buttons and which is coupled via rack and pinion gearing to the drum of the turret tuner. The levers of the different push-buttons have different orientations with respect to the bar so that although each lever is pivoted through the same angle, longitudinal displacement of the bar effected, and hence the setting of the turret tuner, depends upon which push-button is actuated. Upon actuation of a push-button, the bar is locked in its displaced position by means of a leaf spring, and the drum is then locked in position by means of a projection that engages in one of several notches in the drum.