Abstract: When high-speed digital signals are transmitted through a slip ring connection between relatively rotatable systems, the slip ring connection is prone to brief interruptions of contact which introduce extra "ones" or "zeros" into the transmitted digital wave form. In this invention, the binary input signal is split into two paths, one-representing signals causing a current to pass through a first slip ring and zero-representing signals causing a current to pass through a second slip ring. On the output side of the slip rings, the passage of current through one slip ring or the other is used to reproduce the original binary signal; additionally, the combined current flow through both slip rings is used to generate an extra signal which, in the absence of current in either slip ring, indicates a fault.

Abstract: A frequency lock loop circuit has a pair of square-wave pulse generators which are clocked from a common input. The width of the pulses from the first generator is dependent on the frequency of the clocking signal; the width of the pulses from the second generator is dependent on a reference frequency. The difference in the width of the pulses from the two generators is fed back as an error signal to adjust the frequency of the clocking signal until the two waveforms are aligned. In a heterodyne receiver, the clocking signal may be the intermediate frequency signal from the mixer and it may then be adjusted by adjusting the frequency of the local oscillator in accordance with the pulse-width difference signal.

Abstract: A lubricant, and a method for its preparation, essentially comprising colloidal particles of a metal oxide hydrate over the surface of which has been reacted fatty acid molecules having long Carbon chains. The metal used to form the metal oxide hydrate is chosen from the first transition period of the periodic table, and is preferably either Chromium, Manganese, Iron, or Cobalt. The fatty acid preferably has a Carbon chain length in the region of 16 to 24 inclusive and is present in an amount not greater than 20% by weight of the metal oxide hydrate.

Abstract: In order to provide exceptionally high beam deflection speed in apparatus utilizing a magnetically deflected electron beam, such as an electron microscope or an electron beam welding machine, a ferro-magnetic yoke having opposed internal poles arranged to be positioned on opposite sides of the beam is provided with a pair of beam deflection coils on each pole, one coil of each pair being connected in a series circuit including a coil of the other pair and in a sense such that the voltage induced in one pair of coils by a collapsing deflection current in the other pair assists the rising deflection current in the first mentioned pair.

Abstract: A submersible vehicle connectable to a parent surface vessel by an umbilical cable link has an anchorage for that cable link arranged such that the resultant is maneuvered can pass through the center of drag of the vehicle when it is submersed. Accordingly control of the submersible vehicle is facilitated because no excessive disturbing moments are passed to the vehicle by the cable.

Abstract: An expandable fuel storage tank for aircraft has a resilient exterior wall panel in the form of a leaf spring anchored at both ends to a surface region of the aircraft, one anchorage being in the form of a simple hinge and the other incorporating a translatory device so that when the wall panel becomes bowed outwards due to the fuel storage tank being filled with fuel the ends of the panel can move relatively toward one another. The panel is formed as a spring such that when fuel is removed from the fuel storage tank, the panel tends to flatten to resume a position in general continuity with the surface region of the aircraft.

Abstract: A coupling assembly comprising an inner member extending axially through a tubular outer member with a radial clearance all round, the two members being coupled together by flexible but inextensible ligaments arranged to allow limited relative rotational and radial movement between the two members without the two members contacting each other.

Abstract: A powered remotely piloted vehicle which is not controllable at the low landing speeds necessary for landing on a platform of small area is provided with a para-foil type wing deployable at the beginning of a recovery sequence, and is further provided with a rocket ejectable line which is passed to the landing platform and winched in so that the composite flight vehicle and deployed para-foil wing is drawn towards the platform after the manner of a kite.

Abstract: A supersonic two-dimensional intake arrangement for two or more jet propulsion engines has a duct for each engine, a mouth region for each duct, said mouth regions being positioned in adjacent rearewardly staggered rearwardly such that at least one shock wave is common to all mouth regions. Preferably one duct wall is common to adjacent intake mouths.

Abstract: A compact rotary instrument for accurately measuring small movements of a machine tool leadscrew, the instrument having one continuous decimally divided scale which indicates the measurement in either the metric or the inch system as selected by an operator. The instrument encloses a gear system which can be changed from a direct drive condition in which the rotary motion of the leadscrew drives an annular scale at a 1:1 ratio to an indirect drive condition in which the rotary motion of the leadscrew drives the scale through a gear train having two externally formed ring gears and two pinion gears carried on a stub shaft, at a 1.27:1 ratio. The selection is by means of an annular rotatable selector having two spaced marks formed thereon against which the scale can be read by an operator, the rotational positions of the selector and the spacing of the marks being such that when direct drive is selected only one mark is visible by an operator and when indirect drive is selected only the other mark is visible.

Abstract: A digital phase locked loop is described which includes a first gate through which incoming pulses are passed to subsequent data processing circuits, a second gate through which reference pulses having a predetermined pulse repetition rate equal to the repetition rate of the wanted incoming pulses are fed to a reset input of a counter such that each reference pulse resets the counter to zero, and a clock generator for feeding clock pulses to the counter. The counter is thereby repeatedly stepped through a predetermined cycle, the nominal period of the counter cycle being equal to the nominal period of the reference pulses, and means responsive to the number stored in the counter reaching a first predetermined value then latches both the first and second gates open for a predetermined relatively short period in each counter cycle during which the counter passes through its zero state.