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Aviation History
1932
1932 - 0660.PDF
FLIGHT, JULY 1, 1932 Napier "Lions" for Motor»Boats yttr 500-h.p. engine with obvious C^\|| potentialities for high-speed •ZS JlL motor-boat work is the result of converting a Napier " Lion " aero engine. This development has been undertaken by Mr. H. Scott Paine, of the British Power Boat Co., of Hythe, Southampton, and the marine con version is known as the " Power " " Sea Lion." It is the most powerful motor-boat engine produced on this side of the Atlantic. It is expected to accomplish 300 hr. without overhaul, and the altera tions have resulted in an engine of much smaller dimensions than any known marine type which approaches the " Lion's " horse-power. A long series of experiments have preceded this achievement, which gives promise of the development of high speed motor-boats for sporting purposes, and of boats for commercial work with moderate speed and high power. The size of the " Sea Lion " will also enable it to be installed in very small boats for racing, for its greatest length is 6 ft. 3 in., overall width 3 ft. 6 in., and height 2 ft. 10 in. As preparations have been made to con vert a large number of " Lion " engines, it should be possible to market them at a price much lower than that of a new " Lion " aero engine, while the marine version will also be rather more economical than the aero type. During bench tests, when developing 518 h.p., its petrol con sumption was 35 gallons per hr. The power-weight ratio is approximately 2.6 lb. per h.p. developed, and at 2,300 r.p.m. the engine yields 500 h.p. Arrangements have been decided upon for the production of the " Sea Lion " at three different rat ings, the lower two being 400 and 425 h.p. respectively. There will thus be a change in compression ratios, with longer life. A great advantage over engines primarily designed for marine work is gained by the Sea Lion " in its low power-weight ratio, while the design of its cylinder banks in the form of a broad arrow produces a very compact engine. Among the alterations carried out is a clever arrange ment of the manifolds for the main water cooling and the removal of a mass of water pipes from the cooling system, which contributes to the neatness of the marine engine. The cooling system employed results in fresh water being led into the manifolds through honeycomb tubes. When rTi 9 «m mm g»aF M ^^.w" * JmT" ! Qi ^^ ***»«* **! : " _^_ * * ^iflBK BHfc'-- i^^^^^^^^ss - w-s mm An end view of the " Sea Lion." The way in which this conversion for marine use has been carried out makes it an extremely compact engine for its power. the boat is moving salt water is drawn into the manifolds by means of an inlet and suction outlet at the side of the boat. When the boat is stationary a small pump is brought into operation which circulates just sufficient water to cool the " Sea Lion " without making it cold. This simplified system of cooling does away with a bulky pump depending upon high driving power. The " Lion " aero engine hand-starting arrangement—which is greatly in advance of marine engine hand-starting gear—is retained, and there is dual ignition. An interesting alteration is the extension of the crankshaft forward to the reverse gear, which lies in compact form close beside the main crankcase in spite of a self-starter ring and r flywheel having been added to the crankshaft. The self-starter is specially geared and has a Bendix drive, features which keep down the size and weight of the electric motor. Another interesting point is the linking up of the two magnetos and three carburetters to one lever, with the result that the ignition is advanced as the car buretter throttles are opened. Nearly full advance is obtained when the throttles are just over quarter open. Other dimensions of the " Power Sea Lion " are as follows: —The height from shaft centre to under side of reverse gearcase is 3J in., which is an extraordinarily low clearance for an engine of this h.p. Forward from the shaft centre line to under side of crankcase is 1 ft. 1J in. The weight is 1,295 lb. three-quarter view of the " Sea Lion " which gives a good idea of how accessible are the carburetters and other vital parts of the engine. 612 • • •
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