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Aviation History
1946
1946 - 0063.PDF
JANUARY IOTH, 1946 35 Kriffon 130 r 2,000 B.H.P. Developed at 20,000ft. :hanged : New Fuel-metering Pump Griffon 130 has a rated altitude of 16,500ft. as against 13,500ft. for a two-speed engine. In'M.S. the rated altitude is about the same as for the 65, but for that altitude there is an increase of more than 50 b.h.p., whilst in F.S. gear the output has gone up to 1,280 b.h.p.at 3T>5<>oft., which is the greatest altitude power figure so far produced by a piston engine at climbing con- ditions. When modifying the basic design of the two-stage Griffon, existing installation clearances had to be main- tained if the new engine was to power extant fighter aircraft. The arrangement of the third drive to the blower was relatively simple, as the deep wheelcase sump permitted some degree of latitude. The problem of in- creased supercharger capacity was not so simple. How- ever, by making good use of all the available space within the blower casings, in addition to improving in- ternal detail design, an increase in the first and second stage impeller diameters was found to be possible with- out alteration to the outside diameters of the casings. As a result of these modifications, an increase in super- charging efficiency was also obtained. By virtue of careful design, the three-speed blower has incurred a weight penalty of only some 40 lb., whilst the complete engine weighs 2,100 lb. With its maxi- mum output of 2,420 b.h.p., the Griffon 130 is there- fore between 500-750 lb. lighter than any other equiva- lent engine. Power-weight ratio of the engine is 0.865 lb. /b.h.p., and it is this quality which enables a rate of climb of 6,000 ft./min. to be achieved when in- stalled in a fighter aircraft—a greater rate of climb than that obtainable from any comparable engine. Change-speed Mechanism The method of engagement of M.S. or F.S. gear is the same as that on the Griffon 65, but provision has been made in the 130 series to hold the flyweights in a neutral "position when L.S. gear is required. The arrangement of the three-speed blower drive mechanism is shown in the accompanying diagrammatic illustration. To engage M.S. or F.S. gear from the neutral L.S. posi- tion, the flyweights are moved by the hydraulic operat- ing mechanism from the neutral position to engage the gear selected, and, as both ratios are higher than the L.S. ratio, the latter is overrun and the drive allowed to free-wheel. The free-wheel mechanism comprises an outer and inner member and multiple rollers retained in a cage, the inner member being splined to form part of the layshaft and having on its periphery a series of ramps or in- clined faces corresponding to the number of rollers. The outer member is essentially a roller bearing race integral with the inner splined member of the centrifugal clutch. In action the free wheel is such that the drive being through the L.S. layshaft of the inner member, the rollers are forced to run up the ramps, and a solid drive is formed by the wedging action of the rollers against the outer race. When overrunning, the relative speed of the outer member being higher than that of the inner, the rollers are free to rotate and, additionally, are posi- tively held in the free position by means of stops on the roller cage engaging with dogs on the inner mem- ber. A clutch is embodied as a safeguard for the free wheel against shock loads, and is de- signed to slip should the torque load- ing become momentarily excessive. With the introduction of the three- speed gear, it was necessary to modify the reciprocating hydraulic ram used to effect the change from It is apparent from this and the above photographs that the external changes are con- fined to the rear end of the engine.
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