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Aviation History
1928
1928 - 0948.PDF
OCTOBER 11, 1928 BRISTOL " JUPITERS " AT BERLIN : The " Titan " a medium-powered 5-cylinder engine in which standard" Jupiter " parts are employed extensively in its construction. " F.clipse " impulse starter, the hand crank for which is inserted from one side of the engine. Improvements are also to be found in the valve gear. The valve rockers have been mounted on ball bearings, whereby the period between oilings is increased to about 100 hrs. Contact between rocker and valve stem is now by a spherical steel ball, above which is inserted a small felt pad soaked in oil, ensuring the efficient lubrication of this part. Again—and this applies to all four models—the valve rockers are enclosed in neat metal " helmets," which not only protect the rockers from dust, etc., but prevent any oil leakage from the valves being thrown back over the machine. At this point we are afraid we must conclude with the following brief specifications of each type. " Jutriter " Series VI.A.—Bore, 5-75 in. (146 mm.) ; stroke, 7-5 in". (190 mm.) ; volume, 1,753 cub. in. (28-7 litres) ; normal speed, 1,700 r.p.m. , maximum speed, 1,870 r.p.m. ; rated power at normal speed, 415 at 5,000 ft. (1,525 m.) ; rated power at maximum speed, 455 at 5,000 ft. (1,525 m.) ; compression ratio, 6-3 to 1 ; standard weight bare, 720 lbs. (327 kg.). " Jupiter " Series VII.—Same bore and stroke. Normal speed, 1,755 r.p.m. ; maximum speed, 1,950 r.p.m. ; rated power at normal speed, 420 at 12,000 ft. ; rated power at maximum speed, 440 at 15,000 ft. ; compression ratio, 5 to 3 ; weight bare, 760 lbs. (398 kg.). " Jupiter " Series VIII.—Same bore and stroke ; normal speed, 2,000 r.p.m. ; maximum speed, 2,200 r.p.m. ; compres- sion ratio, 5-8 to 1 ; rated power at normal speed, at 4,000 ft. (1,220 m), 440 b.h.p. ; rated power at maximum speed, at 4,000 ft., 480 b.h.p. "Titan."—Core, 5-75 in. (146 mm.); stroke, 6-5 in. (Ifi5 mm.) ; total swept volume, 842 cub. in. (13-8 litres) ; compression ratio, 5 to 1 ; rated normal power, 200 b.h.p. at 1,700 r.p.m. ; maximum power, 220 b.h.p. at 1,870 r.p.m. ; weight dry, 500 lbs. (227 kg.1 ; fuel consumption, 13 gallons per hour ; oil consumption, 2 pints per hour. A service type with higher compression ratio (5-3 to 1) is also produced, developing 220 h.p. at 1,700 r.p.rn. and a maximum of 240 h.p. at 1,870 r.p.m. D. NAPIER AND SON, LTD. ONE of the latest type of aero engines is being shown on Stand 52 by D. Napier and Son, Ltd., of Acton, viz., the Series XI Napier " Lion." The Napier " Lion " (Series XI) is a development of the 450-h.p. Napier engine (Series V) which, for many years, has held sway in the aero engine world. It also embodies many of the principles which proved successful in the 875-h.p. racing Napier engine, which helped so materially to bring the Schneider Trophy back to England in September, 1927. This new Napier engine develops 570 h.p. at 2,585 r.p.m., which is a considerable increase on the 450 h.p. obtained from the " Lion " with which the Heinkel seaplane secured the highest marks in the 1926 YVarnemunde commercial seaplane competition. It has already successfully passed the British Air Ministry Type Test, whilst one of these engines installed in a De Havilland " Hound " recently secured three world's speed records. The main advance with this latest Napier is in the greatly increased power that is obtained without any loss in reliability, whilst it is also streamlined in a manner which makes it easier to install in aircraft. The 12 cylinders—which are arranged in the usual three blocks of four, broad-arrow fashion—are steel forgings, machined all over, with steel water jackets and detachable alumin aluminium cylinder head containing inlet and exhaust passages, valves and valve actuating mechanism. The pistons are of aluminium alloy. There are two inlet and two exhaust valves per cylinder, each fitted with two coil springs, and operated direct by over- head camshafts driven through bevel gearing by vertical shafts from the crankshaft. The whole of the valve mechanism enclosed within a detachable aluminium case. The connecting rods are machined from special high grade steel. The master rod, coupled to the pistons of the vertical block of cylinders, being formed with lugs on either side, to which are attached the short auxiliary rods for the pistons of the right and left groups of cylinders. The big ends are white metal-lined, while anchor pins and other parts work in bushes of ample size. » The crankshaft, which is machined from a solid steel forging has its four throws in one plane and all journal bearings and crankpins are of large diameter and bored out. The shaft is carried in five substantial roller bearings and a large plain bearing at the forward end. Reduction (1 to 1 -885) between the airscrew and crankshaft is through high grade alloy steel spur gears enclosed in the front end of the crankcase. The airscrew shaft—carried on two roller bearings—is fitted with a large double thrust ball bearing taking the thrust of either " tractor " or " pusher " air screw. The crankcasc is of aluminium, stiffened at all necessary points, and the rear cover contains the oil pumps, the drive for the camshafts, magnetos, water and oil pumps. There are two suction and one pressure oil pumps, the former scavenging the oil sump, returning the oil to the supply tank, and the latter delivering oil from the tank to the working parts of the engine, under pressure. Lubrication is by pressure throughout to big ends, gudgeon pins, bearings of camshaft and forward gearing of the crank- shaft. The reduction gears are lubricated by oil projected on to the teeth from a pipe connected to the crankshaft lubricating system. Valve tappets and cams are lubricated 878
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