Abstract: A scroll for directing hot gases into a radial flow turbine includes two annular confronting members which corporate to define a volume; the confronting members are curved in the same axial direction so that one member is inward of the other and support means are included to support the inward confronting member; the configuration ensures that the cross-sectional area of an annular outlet in the radially inner region of the scroll remains substantially constant during variation in scroll temperature.

Abstract: A gas turbine engine power unit (10) comprises a gas generator (11) having a valve (21) located at its downstream end. The valve (21) receives the exhaust efflux of the gas generator (11) and directs it either to a plurality of turbochargers (32) to boost the output power of the unit (10) or to a plurality of heat exchangers (39) to provide regeneration of the unit (10). The valve (21) comprises a rotary portion (20) which rotates within a static portion (28) to provide alignment of apertures within both portions (20,28) to facilitate the direction of the gas generator (11) exhaust efflux.

Abstract: In the manufacture of a wax pattern for use in the lost wax casting of a bladed rotor of the radial flow type, the bladed region of a master pattern is enclosed by a curable epoxy resin/aluminium powder composition. Sufficient of the cured resin composition is then machined away so that a plurality of resin composition segments are defined, one segment being interposed between adjacent blades on the master pattern. The segments are then removed from the master pattern and placed in an appropriately configured die member so as to define a complete die for the production of a wax pattern in the form of the master pattern.

Abstract: A gas turbine engine power unit (10) comprising a gas turbine engine hot gas generator (10a), the exhaust efflux of which drives a turbine (20) having a power output shaft (22). The exhaust efflux from the turbine (20) is directed into a chamber (23) having two outlets (24,25) to atmosphere. The outlets (24,25) are provided with valves (26,28) which are operable to ensure that only one outlet (24,25) is open at a given time. The first outlet (24) contains a heat exchanger (15) whereas the second outlet (25) contains a further turbine (30). The further turbine (30) drives an air compressor (32) the output of which is directed to an air inlet (36) of the gas turbine engine (10a) in order to facilitate a boost in its output power.

Abstract: A rail gun assembly (10) having rail electrodes (11, 12) which are of toothed cross-section configuration and an armature (15) which provides an electrical interconnection between the rail electrodes (11,12). The armature (15) is made up of three electrically conductive portions (24,25,26) which are separated by insulators (27,28). The electrically conductive armature portions (24,25,26) are so configured that varying amounts of electrical current pass through them as the armature is operationally accelerated along the gap between the rail electrodes (11,12). Localized overheating of the armature (15) is therefore substantially reduced.

Abstract: A rail gun (10) comprising two spaced apart elongate co-extensive rail electrodes (11,12) having confronting surfaces which are of toothed cross-section configuration. Alternate tooth flanks (21) have the outlets of a plurality of nozzles (24) located therein. The nozzles (24) direct helium into the gap (14) between the rail electrodes (11,12). The helium provides electrode (11,12) cooling as well as providing less resistance to armature (15) acceleration than would be the case with air.