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Aviation History
1955
1955 - 1451.PDF
30 September 1955 561 LEONIDES MAJOR PROGRESS 3,000 Hours' Bench and Air Running Completed SEVERAL aircraft—both fixed-wing types and helicopters-are now flying on the power of the new Alvis LeonidesMajor, and this engine has now acquired considerable importance for both civil and military projects. At this year'sS.B.A.C. Show it was seen airborne in public for the first time in the Handley Page Herald and in the Westland Whirlwind. ' The single-row Leonides has given extensive service inProvosts, Princes, Pioneers, Dragonflies and Sycamores, and the two-row 14-cyhnder Major, which was developed from it, hasnow completed some 3,000 hours of bench and airborne running Progress towards type-testing at the designed power is reported tobe satisfactory, and an internal modification will enable the type- test at a guaranteed minimum of 850 h.p. to be completed in thenear future. This modification is the stiffening of the cam ring, since differential expansion of the steel ring and the forged alloycrankcase was seen to cause inefficient valve operation, which in its turn led to a power of only 825 h.p. in two "dummy run"type-tests carried out earlier. With the 4 per cent minus toler- ance in power which has to be allowed for in the first twentyengines submitted for the official power rating to be set, a guaranteed 850 h.p. is expected. Engines now installed in the various aircraft are giving 825 h.p.,since they have not yet been modified. The company's test-bed, the Marathon, is being used to complete 250 engine hours assoon as possible in order to establish this time as the initial over- haul period, but it is hoped soon afterwards to raise the period to400 hr. By 1957, when the Herald is first due to be delivered to operators, overhaul periods will certainly be up to 400 hr,but in ali probability will already have reached 600 hr. When, recently, a member of the staff of Flight visited Bagintonand flew the Leonides Major Marathon it had already completed 140 engine hours without trouble. The test-bed nacelles are, ofcourse, identical with those of the Herald, and it was clear that cooling and other items which are generally a function of theinstallation are all satisfactory. The cowling gills are electrically operated and oil temperatures can be easily controlled by them.In this first test-bed no particular effort has been made to relate the throttle movement exactly to power response—nor is anygreat alteration absolutely necessary. Response is a little slow over the lower range of throttle movement. The engines are, "Flight" photograph Alvis Leonides Major Position of crankshaft Number of cylinders Bore (in) Stroke (in) Capacity (cu in) Compression ratio Supercharger ratio Overall diameter (in) Overall length with accessories (in) ... Fuel grade Maximum Take-off Power Rating b.h.p r.p.m. Boost (Ib/sq in) Altitude (ft) Fuel consumption (pt/b.h.p./hr) Maximum Power Rating b.h.p r.p.m. Boost (Ib/sq in) Altitude (ft) Fuel consumption (pt/b.h.p./hr) Maximum One Hour Power Rating b.h.p r.p.m. Boost (Ib/sq in) Altitude (ft) Fuel consumption (pt/b.h.p/hr) Maximum Continuous Power Rating b.h.p r.p.m. Boost (Ib/sq in) Altitude (ft) Fuel consumption (pt/b.h.p./hr) Maximum Weak Mixture Power Rating b.h.p r.p.m. Boost (Ib/sq in) Altitude (ft) Fuel consumption (pt/b.h.p./hr) Weight Net dry weight to E.D.M. 25 (Ib) A.Le.M. 1-1 horizontal 14 4.8 4.41 1,117.8 6.8:1 6.535:1 38.925 70.896 (max.) 100/130 850 3,000 +n Sea level 0.80/0.85 870 3,000 4 91 1,750 0.78/0.82 635 2,900 + 3*8,500 0.68/0.72 515 2,600 Zero 11,500 0.545/0.575 1,200 A.U.M. 1-6 vertical 14 4.8 4.41 1,117.8 6.8:1 6.535:1 38.925 54.858 (max.) 100/130 860 2,900 1,500 0.78/0.82 635 2.900 + 31 8.500 , 0.68/0.72 535 2.750 Zero 12.500 0.550/0.590 1,050 CRANKSHAFT SPEED (r.p.m) 20 22 24 26 28 30 CRANKSHAFT r.p.m. x 100 IO IS 20 25 30 35 ALTITUDE ft x I,OOO The nacelle of the Leonides Major in the Marathon test-bed is identical with that of the Herald, and is shown in the heading illustration with cowl- ing gills three-quarters open. The petal cowling hinges just aft of the exhaust pipe and air outlet grille. Sea-fevef (left) and altitude (right) performance curves for the present Leonides Major.
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