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Aviation History
1954
1954 - 1771.PDF
The key to this longitudinal section is as follows: A, oil from metering pump; 6, oil from pressure pump; C, oil to scavenge pump; D, oil to accessories; E, oil to bevel gear box; F, main fuel feed; G, fuel from priming solenoid; H, drains; J, pitot pressure to engine control; K, oil flow; L, air/oil vapour; M, eighth-stage bleed and cooling airflow: N, labyrinth seal. ANGLO-AMERICAN JEWEL . . . numbered engines are for the U.S.A.F. and go into the Republic F-84F Thunderstreak and RF-84F Thunderflash and also the B-57 and RB-57 series of Martin-built Canberras. The even- numbered Sapphires are Navy engines for the North American FJ-3 and FJ-4 Furies. New aircraft reported to use the Sapphire are the Douglas A4D Skyhawk attack machine for the Navy and the Air Force's Lockheed F-104 fighter. The 13-stage compressor has steel blading, which is through- riveted to forged-steel discs, there being two discs per stage of blading as in the Viper (Flight, August 7th, 1953). The discs are mounted on a large-diameter hollow shaft forged in light alloy. No less than 74 surfaces of different diameters must be machined on each shaft, of which 32 are close-tolerance seats for the discs, shroud rings or other parts. The untapered casing is a thin- walled light-alloy assembly, ribbed for strength, made in top and bottom halves. Just beyond the eighth stage, a row of bleed holes permits air to escape into the hollow compressor shaft, from which it eventually escapes as a cooling flow, at the front, centre and rear main bearings, between the two turbine rotor discs and behind the rear turbine (see cross-section at top of this page). The combustion chamber is entirely Armstrong Siddeley in concept and detail design. "Walking stick" vaporizing burners are used (36 of them) arranged as shown. Wright have expressed themselves well satisfied with the J65s combustion and the fairly frequent faults experienced in F-84F engines some nine months ago were rarely due to this factor. The two turbine rotors carry 110 blades (high-pressure) and 75 blades (low-pressure), respectively, and both rows of nozzle guide vanes (or turbine stators) have 108 blades. Blading is of Inconel, with ground fir-tree roots. The structure of the engine is clearly shown, and is fairly straightforward. The power take-off to the accessories is shown in one sketch, and it is seen to pass down one of the hollow struts supporting the front main bearing. Another of these hollow struts contains a shaft driving the oil pump. The oil is Esso Aviation Turbo Oil 15, and it is cooled in a fuel-cooled heat- exchanger. The starter is simply bolted on the front of the engine; sometimes an electric motor is used, but die Bendix fuel-air unit is more common and is shown on the front of each of the Buick- built J65s in the heading photograph. POWER TRANSMISSION SHAFT FUEL SECONDAKY AIR AIR FROM _. PRIMARY, COMPRESSORm AIR # COOLING AIR TURBULENCE PIN L fay^gy. COMBUSTION OF PROPER RATIO FUEL-AIR MIXTURE' UEL VAPOUR siwtfss \V •— >i COMBUSTION OF FUEL-AIR IGNITER PRIMER FUEL TUBE HYDRAULIC- PUMP DRIVE SCAVENGE PUMP PRIMARY AIR AND FUEL TUBE INNER LINER HEAT SHIELD SCAVENGE PUMP This view of the upper part of the annular combustion chamber is looking forward, downward and to the right. (Above) Vaporizing combustion shown diagrammatically. The fuel pump, made by Thompson Products, Inc., is of Dowty design (type ENG.t29), and it delivers fuel to the chamber at about 3% Ib/sq in above the pressure in the walking-stick tube. The accessories are driven by a shaft passing down the interior of one of the four hollow struts in the intake of the engine. The two assemblies shown are separated only for clarity; the main bevel box is drawn twice.
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