History of aicraft piston engines

As mentioned earlier p 13 the wright brothers used

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Unformatted text preview: d isplaced by the "high-tension" system with spark plugs which was used i n all other successful airplane engines, and, in its essentials, is accepted p ractice to date for all spark-ignition engines. 80 C eramic-insulated spark plugs were generally used in the United States before 1921. Both mica and ceramic plugs were used in Europe. From a bout 1921 t o 1940 m'ca plugs were generally used. The development of new ceramic materials about 1940 caused a universal change to this m aterial. C ARBURETION. A t the time of the Wright brothers' first flight, little was k nown about carburetion, and various devices were used to introduce fuel to air. As mentioned earlier (p. 13), the Wright brothers used gravity fuel feed from a small can to a heated surface in the inlet pipe. Manly used a large sheet-metal box filled with porous wooden blocks, a scheme o riginally conceived by Balzer. These blocks were saturated with fuel, a nd the engine air was drawn past them, in the hope that a combustible m ixture would result. The Antoinette engine and all of the Wright b rothers' engines produced during 1907-1912 used a small pump to inject fuel into the inlet ports. The carburetion system used for the Gnome r otary engine has already been described (p. 25). All these systems r equired experimental adjustment, good for only one engine speed. M eanwhile, float-type carburetors were being developed for automobile use, and these were used by most aircraft engines after the Gnome a nd Antoinette. Float-type carburetors were used by the Wright brothers on their later engines, and were generally used for aircraft engines up to a bout 1935. A floatless carburetor was introduced by the ChandlerGroves Corporation in 1935, and the Stromberg floatless injection-type c arburetor became operational about 1938. Since that time most military and transport engines have used floatless-type carburetors, many of t he injection type. Light-plane engines have, generally, continued to use float-type carburetors, although injection systems are available for this t ype. D irect injection into the individual cylinders was used in gasoline engines for a short time on some Pratt & Whitney Wasps in 1 931-1932. T his method was developed to service use in World War II in G erman military engines. It was adopted by Wright Aeronautical Corporation for their R-3350 engine in 1944. I njection through nozzles located at each inlet port, first used on the A ntoinette engine of 1906, h as been used to a limited extent in light-aircraft engines since about 1946. S TARTING. H and starting by the propeller was standard before 1920. S ubsequent development included simple hand cranks, hand cranks with i nertia flywheel, cartridge starters, air starters, and finally the present electric starter with storage battery. F UEL INJECTION. 81 B EARINGS AND LUBRICATION. M ost radial engines, even as early as the G nome (fig. 20), used ball or roller bearings for the crankshaft. This practice has been continued with few exceptions, of which...
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