Abstract: A nozzle is provided which is capable of varying the direction of discharge of a fluid. As shown in FIG. 2 the nozzle 11 has sidewalls defining a circular opening 12 and a plug 14 mounted within the nozzle for transverse movement in the plane of the nozzle outlet. Thus a component of velocity can be imparted to the jet in any direction around 360.degree. in the plane of the nozzle outlet.Operation of the nozzle is by means of a plurality of piston-in-cylinder devices 18,20 acting between the plug 14 and the nozzle sidewalls. The plug is mounted on an arm 15 in a universal joint 16.

Abstract: In a coupling (9) between a hub (10) and a shaft (11) internal splines (12) of the hub are interdigitated with external splines (13) of the shaft. The splines are helical. The hub and shaft are further connected by axial pins (14) arranged in bores (15) which are parallel to the common axis (16) of the hub and the shaft and which intersect the interdigitated splines. A screw (21) in the hub engages an end (24) of the shaft. When the screw is tightened the hub is drawn along the hub. The different helix angle of zero result in that the hub becomes locked against axial movement on the shaft and the splines of the hub are urged circumferentially into engagement with the splines of the shaft thereby to take up circumferential clearance between them. The force applied by the screw applies compression to the shaft and tension to the hub so that Poisson's Law opperates to close radial clearance between the hub and the shaft.

Abstract: A brush seal which comprises a plurality of tightly-packed bristles (3) sandwiched in a space between a pair of axially-spaced annular side-plates (1,2). In order to minimize the gaps between the bristles at the outer radius of the seal the cross-sectional area of the space, and/or the bristles is varied, or alternatively the bristles are formed in an involute shape, and the cross-sectional area of the space is constant at all radii.

Abstract: A gas turbine engine power plant comprises a main gas turbine engine terminating in a jet pipe in which a free turbine is mounted. The free turbine is adapted to drive an auxiliary compressor. Means are provided such that a portion of the gas turbine engine efflux may be directed through the auxiliary turbine such that the auxiliary compressor augments the efflux from the main engine. Alternatively the entire gas turbine engine efflux may pass directly through the jet pipe.

Abstract: A ducted fan gas turbine powerplant consists of a core gas generator, which may be a single or two-shaft gas generator, and which drives a fan at the downstream end of the powerplant. The exhaust from the gas generator is mixed with flow in the fan duct and the fan operates on the mixed stream as a working fluid.