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Aviation History
1948
1948 - 1265.PDF
August izth, 1948 FLHHT 185 Detail of compressor casing to show the annular duett in the drum, and the outlet elbows to the delivery pipes for turbine coolin Combustion components including the intake cup, combustion chamber, and fabricated flametube, with an igniter plug and a burner nozzle stage disc is cooled by air tapped from the seventh com- pressor stage and externally piped to an annular collector chamber formed in the rear end of the turbine shaft shroud. Six axial pipes take the air from the collector chamber to a second annular chamber venting direct to the disc face. The cooling air delivered to the inter-disc faces is tapped from the tenth compressor stage and fed through one of the spokes of the turbine rear casing into an annular chamber formed in the casing around the rear bearing housing. Part of this air is used to compensate the thrust component imposed on the turbine discs as a function of the gas flow, a piston in the form of a pressure diaphragm being carried on the tail of the turbine shaft for this purpose. A cover plate bolted over the hub of the turbine rear casing acts as a reaction face for the balance diaphragm, and. the air supplied for balance purposes is vented into the core of the turbine tail shaft, from whence it is led through drillings to the inter-disc faces. The remaining air from the annular chamber in the casing is allowed to leak past the labyrinth seals around the rim of the balance diaphragm and so gain access to the rear face of the second-stage disc. Lubrication to the turbine rear bearing is in conformity with the accepted standard of oil / air mist, the oil being fed from the metering pump to the top of the uppermost "spoke" of the turbine rear casing, at which point air is also delivered from a filter unit fed from the fourth com- pressor stage. All the remaining bearings in the Naiad are lubricated via internal drillings, the oil afterwards draining back to the sump formed in the base of the reduc- tion gear casing, but, in common with the turbine rear- bearing, the turbine-shaft front-bearing and the bearings supporting the compressor shaft are all supplied with oil delivered by the main metering pump. An oil cooler is boused in a separate trunk beneath the compressor, and the cooling airflow for this is abstracted from the main intake ^o Hxe compressor at the hollow spinner delivery. C. B. B-W. '••"•-•-..."• . . NAPIER NAIAD DATA Max. diameter 28ln length (airscrew cone to exhaust outlet flange) <8fin Net dry weight 1,0951b + 2£ per cent Oil eomumption *t max. r.p.m. I pint/hr. Oil capacity ... 2if*'l- Airscrew rotation Right-hand tractor Left: VtnidUWSM UHBUfH IUIDJM assembly tho&ggWBhig-air flow-paths to the turbine disc faces, and lubrication flows at the shaft bearings. * Maximum power curves for air speeds against altitude, with fuel consumptions, md, at right, general performance curves for see level static conditions. FUEL CONSUMPTION GALLS HR- SEALEVEL 1OpOO 20,000 3Q0OO ALTITUDE-FEET
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