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Aviation History
1912
1912 - 0503.PDF
CORRESPONDENCE The name and address of the writer (not necessarily for publication) MUST in all cases accompany Utters intended for insertion, or containing queries. Correspondents communicating with regard to letters which have appeared in FLIGHT, would much facilitate ready reference by quoting the number of each letter. The Cochrane Engine. [1563] Now that the question of aeroplane engines is prominently before the public, I think the enclosed photos and diagrammatic COCHRANE'S ENGINE.—At top engine running with rotary valves at 2,000 r.p.m.; in the centre the carburettor side Is seen, showing induction-pipe and gearing on top:~at bottom the rotary valve cover and housing. drawing of my new revolving-cylinder rotary-valve engine may be interesting to some of FLIGHT readers. The chief features of this engine are improved internal cooling, positively operated exhaust and inlet-valves and throttle control. I know that the majority who profess to represent British technical opinion on the subject have prophesied the death of the revolving- cylinder engine within the next 18 months, but I venture to think that it will still retain its premier position if internal cooling can be improved and mechanically-operated valves used, more horse-power will then be developed on the same bore and stroke by increasing the compression, and less lubricating oil will be used. If the engine can be throttled greater economy in petrol will also be possible. I know the Gnome and Indian Motor Bicycle Co., of America, and others have spent large sums of money in trying to produce a successful revolving cylinder engine with mechanically-operated inlet-valves, but the trouble has always been bad internal cooling, and the lubricating oil collected inside the pistons by cen trifugal force becomes carbonized, the excessive heat causing the pistons to seize up after the engine has been running for a short time. I rectify this difficulty by drawing theairforthe carburettor through the cylinders and piston walls when the piston is at the bottom of its stroke,, this system keeps the pistons and cylinders cool, warms the air for the carburettor, and sweeps all the oil which escapes from the bearings up the induction-pipe to lubricate the rotarj-valve in the head of the cylinder. Great economy in petrol and variation of horse-power can be effected by a careful adjustment of the throttle and air-valves, shown working in crank-shaft, the quality of the mixture can be varied by moving the air-valve, the quantity by the throttle. When the machine is vol planing the throttle is pulled open and a needle-valve, shown, shuts off the petrol altogether, only pure air passes through the cylinders, and the engine is controlled by the throttle-lever instead of the spark. Although this engine works at a pressure of si atmospheres, it does not get excessiv<ly hot ; this I attribute to the large free ports and the exhaust and incoming-gases passing through the same valve-port. The disc- valve is also isolated from the combustion-chamber, and is effectively cooled by the air-cooled head and cover. No. I photo shows the experimental engine running at 2,000 revs, per min. ; No. 2, the carburettor side of the engine ; No. 3, the valve in its housing, the valve-housing, the valve, and valve-cover. The advantages this rotary valve has over other valve-gears are: that it is positively operated, noiseless, and without vibration at high speeds, the pressure on the valve-iace is centralized and reduced to an area equal to the area of the port in the disc-valve, there is a double seal on the gases, which makes leakage impossible. The valves were a loose fit five months ago when the engine was completed, and your representative saw it running ; now the oil has carbonized all round the valve-seating the compression is equal, if not better, than a mushroom-valve engine with its valve freshly ground in. Within the last five months I have asked over twelve leading makers of British engines to send a representative to see the engine running, with a view to taking it up ; so far, none have come. It is now being placed with an American firm, who have convinced themselves that — — *<» re„nam» UlACHAHer fa/ir SimiK 503
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