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Aviation History
1928
1928 - 0619.PDF
33 JULY 5, 1928 THE NAPIER "LION" SERIES XI Cylinders.—Steel forgings, machined all over, with steelwater jackets. Detachable aluminium cylinder head con- taining inlet and exhaust passages, valves and valve actuat-ing mechanism. Pistons.—Aluminium alloy, fitted with two gas and twoscraper rings. Hollow gudgeon pins of large diameter. Valves.—Two inlet and two exhaust per cylinder, eachhaving two coil springs and operated direct by overhead camshafts driven through bevel gearing by vertical shaftsfrom the crankshaft. The whole of the valve mechanism is^enclosed within a detachable aluminium case. Connecting Rods.—Machined from special high-grade steel.The master rod, coupled to the pistons of the vertical block of cylinders, has lugs formed on either side, to which areattached the short auxiliary rods for the right and left groups of cylinders respectively. The big ends are whitemetal lined. Anchor pins and other parts work in bushes of ample size Crankshaft. —Machined from a solid steel forging. Thefour throws are in one place and all journal bearings and crankpins are of large diameter and bored out. The shaftis carried in five substantial roller bearings and a large plain bearing at the forward end. Airscrew Drive.—Airscrew shaft rotates clockwise (viewedairscrew end), and is carried on two roller bearings and fitted with a large double thrust ball bearing, to take thethrust of either a tractor or pusher airscrew. The reduction between airscrew and crankshaft is through high-gradealloy steel spur gears. The shaft and its gear and cover can be withdrawn from the crankcase. Crankcase.—Of aluminium alloy, stiffened at all necessarypoints, and having arms on either side for attachment to engine mounting of aircraft. The front end encloses thereduction gearing for the airscrew shaft, together with the shaft and bearings. The rear end cover contains twoscavenge oil pumps, pressure oil pumps, and the drive for the camshafts, magnetos, water and oil pumps. Lubrication.—By pressure throughout to big ends, gudgeonpins, bearings of camshaft and forward bearing of crankshaft. The reduction gears are lubricated by oil projected on tothe teeth from a pipe connected to the crankshaft lubricating system. Valve tappets and cams are lubricated by the oilescaping from the camshaft bearings, which drains into the sump. An adjustable pressure relief valve is incorporatedin the system. Two suction and one pressure-type pump are fitted ; the former scavenge the oil sump and return theoil to the supply tank, and the latter takes the oil from the supply tank and delivers to the working parts of the engineunder pressure. Two oil niters are provided, one between the suction pumps and supply tank, and one between latterand pressure pump. Water Pump.—Centrifugal type, mounted to rear end ofengine and running at crankshaft speed. Its spindle is fitted with a gland and a screw-down greaser. Water isdelivered through a separate outlet to each of the three cylinder blocks. Carburettor and Induction System.—Triple Napier-Claudelcarburettor, water-jacketed. The body, of aluminium, is carried on a bracket on the rear end cover. The gas-inletpipes to the induction on the cylinder heads are of steel and water jacketed. Altitude control, interconnected withthrottle. Ignition.—-Two special 12-cylinder magnetos, rotatinganti-clockwise, mounted on platforms at rear of engine. Special distributors are fitted to facilitate starting by hand,and advance and retard links and levers are interconnected with the throttle control. Starter.—Napier petrol starter provided, by means ofwhich fuel is pumped into the cylinders and ignited by a hand-starting magneto (not supplied with engine) operatedthrough the engine magneto distributors. Number and Arrangement of Cylinders.—12, in three blocksof four each, 60 deg. Cooling.—Water.Bore.—5J in. (140 mm.). Stroke.—5J- in. (130 mm.). Compression Ratio.—6 to 1.Power.—Normal, 530 b.h.p. at 2,350 r.p.m. Maximum permissible, 570 b.h.p. at 2,585 r.p.m.Airscrew.—Clockwise (airscrew end) at 1 to 1-885 reduc- tion ratio of crankshaft. Carburettor.—Triple Napier-Claudel. Ignition.—Two, special 12-cylinder magnetos.Weight.—995 lbs. (452 kg.), complete with airscrew boss, reduction gear, hand starting gearless magneto.Specific Weight.—On rated power, 1-879 lbs./h.p. On average power at maximum speed, 1 -745 lbs./h.p. Length o.a.—5 ft. 1 in. (1 -55 m.). Width o.a.—3 ft. 6 in. (1 -067 m.). Height o.a.—3 ft. 3 in. (0-99 m.).Fuel Consumption.—Average at full load, 0'50 lb. h.p. hour (0-227 kg./C.V./h.).Oil Consumption.—Average, 00235 lb./h.p./hour (0-0168 kg./CV./h.). 567
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