Abstract: A gas laser comprises an optical cavity, a coaxial transmission line at least partially disposed in the optical cavity, a lasant gas disposed in the cavity, and means for transmitting at least one electrical pulse progressively along the transmission line to generate a travelling wave of ionization to pump the lasant gas.

Abstract: A gyroscope system comprises a dual-axis rate gyroscope (1) including angle pick-offs and rotor torque applying device (5), and a control circuit (3) arranged to supply a control signal to the rotor torque applying device (5) in accordance with the output angle sensed by the angle pick-offs. The system further comprises an angular acceleration sensor (2) which is independent of the dual-axis rate gyroscope and is arranged to output a signal to the control circuit (3). The signal modifies in accordance with the sensed angular acceleration the control signal supplied to the torque applying device (5). Preferably the angular acceleration sensor (2) forms part of a guidance system independent of the dual-axis rate gyroscope (1).

Abstract: A gyroscope system includes a gyroscope (1), angle pick-offs (5) and a control circuit (6,7). The angle pick-offs (5) sense the tilt of the gyroscope's rotor and generate a signal which is received by the control circuit (6,7). The control circuit generates a control signal which causes a torque to be applied to the rotor. The control circuit includes both a primary integrator (6) which integrates the signal from the angle pick-offs (5) and a secondary integrator (7) which integrates the signals output by the primary integrator (6).In one example an independent angular accelerometer provides a further input to the secondary integrator (7).

Abstract: A method of forming composite articles from components (12, 14, 16) is described in which the components are joined by adhesive at their interfaces (18). The components have cavities (22) and the adhesive is compressed while it sets by placing magnetically attractable particulate material (20) into the cavities on one side of the interface and placing magnets (26) on the other side of the interface so that the attraction between the magnets and the particulate material compresses the adhesive. The particulate material may be removed from the cavities after the adhesive has set through apertures (24).

Abstract: An aircrew support system for supporting a pilot's head, and optionally his torso, during high g maneuvers, enabling him to maintain his head in an upright position and thereby increasing his awareness of the situation at all times outside the cockpit comprises at least one head support line (3) adapted for connection between the pilot's head/helmet (4) and the seat (1), accelerometers for measuring the g force acting on the pilot/aircraft and a tension structure for applying a continuously variable tension to said support line of a magnitude determined by the magnitude of the current g force acting on the pilot/aircraft. The support system may include a restraint system, for restraining the pilot in a predetermined position during ejection and for disconnecting the support line on ejection.

Abstract: The present invention provides a process in which components made of aluminum or an alloy thereof can be diffusion bonded together; the process involves chemically treating the components to remove aluminum oxide on the surface of the components, subjecting them to grit blasting and to a second chemical oxide removal step and finally pressing the components together under heat until they form diffusion bonds. The resulting composite can be superplastically formed to shape.

Abstract: A jet pump comprises a nozzle (1) for a high speed primary flow, a mixing tube (2) into which the primary flow is directed by the nozzle (1), and an inlet (3) to the mixing tube (2) for a secondary flow, the inlet (3) surrounding the primary flow nozzle (1). Means (2') is provided for changing the cross section of the mixing tube (2) abruptly in order to produce a rise in static pressure immediately downstream, thereby increasing mixing of the primary and secondary flows, stabilizing the mixing process and enabling significant noise reduction when used in engine testing apparatus.

Abstract: Measurement of flux density at the edges of the footprint of an RF transmission from a spacecraft with a view to determining the spacecraft antenna pointing error is difficult because of atmospheric fading local to the measuring station. Previous proposals to permit determination of pointing error in the face of such effects involve additional hardware on board the craft. Herein, it is proposed to induce a relatively small repetitive scanning motion of the spacecraft hence producing an oscillatory flux density variation at peripheral ground stations and then measuring the oscillatory component relative to the average flux density--frequency analysis equipment operable to discriminate the known frequency of the variation over a plurality of wavelengths can be used giving substantial accuracy improvement. A series of measurements enable the diurnal pointing error pattern to be determined and hence a spacecraft attitude correction command program to be produced.

Abstract: A technique for providing roll orientation information for a course corrected projectile in which the projectile is provided with three off-axis detectors subjected to a scanning laser beam. The time which elapses between the laser beam travelling from one detector to another is all that is required to calculate the roll orientation of the projectile.

Abstract: A superplastic forming apparatus is described in which a blank of superplastic material is formed onto a die located in a pressure cavity. The die, which is preferably made of ceramic material, is removable from the cavity and requires no special connections for gas or vacuums ducts and therefore is cheap to manufacture. The use of a separate die also allows accurate monitoring and control of the pressure on the die side of the superplastic blank.

Abstract: Apparatus for and a method of rendering selected areas 17, 18 of an aircraft canopy 2 receptive to an adhesive by means of which a detonating cord 7 is attached in loop form to the canopy, to facilitate fracture of the canopy for pilot ejection in an emergency, comprises pretreating those areas 17, 18 by corona discharge. The canopy 2 is mounted in a jig 10 shaped to conform with the canopy and having rebates 11 for accommodating discharge electrodes 12 located at a distance from the canopy 2. A pump 16 is provided to remove ozone formed due to the discharge and trapped between the canopy 2 and the jig 10.

Abstract: A fastener for use with aircraft structures comprising composite materials has improved electrical characteristics designed to reduce damage by lightning strikes. The fastener comprises separate nut and bolt portions and a cage member (4, 1, 6). The nut (4) and the head portion of the bolt 1 both have beveled edges which in use are countersunk in the composite materials to enhance electrical contact between the fastener and aircraft structural members (2, 5). The nut (4) is captively mounted inside the cage member (6) and is moveable, within pre-determined limits, inside the cage (6) so that it may be axially aligned with and the bolt screwed therein, thus compensating for any initial non-aligment of the nut (4) and bolt (1) due to a complex shape of the aircraft structure necessitated by aerodynamic or other considerations.

Abstract: A lock nut assembly comprises a sleeve bolt (1), a clamp bolt (6) and a locking bolt (7). The sleeve bolt (1) has a hollow shank with an internally threaded portion (5) at one end and a head (3) having an axial bore (2) extending through it at the other end, at which it is internally threaded (4). The clamp bolt (6) also has a hollow shank with an externally threaded central portion (9) and an internally threaded portion (10) at one end (10) and a head (8) at its opposite end. The locking bolt (7) has an externally threaded portion at one end (12) and a head (11) at its opposite end. The central portion (9) of the clamp bolt (6) and the internally threaded portion (5) of the sleeve bolt (1) are dimensioned for co-operation with threads of one hand, and the second portion (10) of the clamp bolt (6) and the externally threaded portion (12) of the locking bolt (7) are dimensioned for co-operation with threads of opposite hand.

Abstract: A jet pump is provided for pumping a secondary fluid through a duct by injecting a primary fluid into the duct in the form of sheet-like jets lying in a plane parallel to the direction of flow of secondary fluid through the duct.

Abstract: A hydrodynamic gas journal bearing system using rotating bushes which are able to radially move relative to a shaft, the movement being controlled by a spring support system, and in which a degree of dynaMic imbalance of the rotating system is incorporated, these features and the design of the system being together such as to suppress the onset of self-excited instability (half-speed whirl) of the rotating system.

Abstract: An integrated circuit device including a substrate (2), power supply buses (V.sub.DD, V.sub.SS), and a number of terminal pads (1) has an electrostatic discharge protection circuit associated with one of its terminal pads (1). The protection circuit comprises a diode (D1) directly connected between the pad (1) and one of the power supply buses (V.sub.DD, V.sub.SS), a punchthrough transistor (TR1) directly connected to the other one of the power supply buses (V.sub.DD, V.sub.SS) and a resistive path (R1) connecting the pad (1) to the remainder of the integrated circuit. Static charges applied to the pad (1) are transmitted to the one or the other power supply bus (V.sub.DD, V.sub.SS) via the diode (D1) or the punchthrough transistor (TR1) rather than being transmitted to the remainder of the integrated circuit.

Abstract: An asynchronous communication system writes data from an input (I) to an output (O) via region of shared memory. The region of shared memory is divided into four slots (S1-S4). The system includes means to write data (1, 5, 6) which select a pair of slots S1, S2; S3, S4) not currently selected for reading and one of the slots of the selected pair which is not the slot last written to. Means to read date (2, 3, 4) select the slot last written to and route data from that slot to the output (O) so that fresh coherent data is communicated fully asynchronously from the input (I) to the output (O).

Abstract: An electro-hydraulic actuator assembly comprises a master piston-and-cylinder 32, 42 connected to be driven by a rotary actuator 56 and hydraulically connected to a slave master piston-and-cylinder 12 coupled to an output member, e.g. a throttle linkage rod 10, for automatic control of the displacement of the member 10. An override for manual control of the member 10 is provided by a valve 60 which, when opened, hydraulically shortcircuits the member 10 by equalizing pressures on the two sides of the slave piston 16. To re-establish automatic control and synchronize master and slave, a (possibly remote) controller 80 shuts the valve 60 and drives the actuator 56 until master and slave pistons both attain end positions; if necessary, by reopening valve 60 for a short time and continuing to drive the actuator 56.

Abstract: The invention concerns a nose piece adaptor for a manual or power feed drill. The adaptor has a hollow cylindrical sleeve (11) surrounding the drill bit and having on the outer surface of one end thereof a taper lock (13) for engagement with location studs (17) in a template (16). At its other end the sleeve (11) can be threadedly engaged or integral with the drill. The sleeve (11) has a sprung, quick-release ball (25) lock mechanism for engaging with or disengaging from a peripheral locking groove (26) of a nose piece (14) inserted into the bore of the sleeve (11). The nose piece (14) is a simple cylindrical rod with a bore (30) for the drill bit.

Abstract: The invention concerns a wing leading edge arrangement for aircraft in which a slat 10 is provided forwardly of a fixed leading edge 11 and is movable between a retracted configuration in which it lies closely adjacent the fixed leading edge 11 and a deployed configuration in which it is spaced from the fixed leading edge 11 to define a slot 13. The slat 10 includes attachment means 14 to two chordwise extending support tracks 12 slidably mounted on the leading edge 11. An aperture 22 in the leading edge skin 23 accommodates the attachment means 14 when the slat 10 is retracted. A shutter arrangement 27 mounted within the fixed leading edge is movable between an aperture closing position when the slat is deployed and a retracted position when the slat is stowed.