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Aviation History
1911
1911 - 0359.PDF
APRIL 22, 1911. IftlGHT PHOTOGRAPHS and leading particulars of the Isaacson engine have already been published in FLIGHT, and the accom panying detail sketches will, therefore, be of interest to readers on their own account. Special features of this engine are that, although it is of the radial type it is a stationary motor, and although it has a propeller mounted concentrically . u i?S crank-shaft, nevertheless the propeller revolves at half the engine speed. One of the accompanying sketches shows the manner in which the cylinders are fastened to the crank-chamber, the crank-case is a two-part aluminium casting divided circumferentially in the middle and held together by seven bolts. At intervals round the periphery large circular holes are cut to receive the cylinders, which are clamped between the two parts of the crank-chamber. A collar is machined on the lower end of the cylinder wall, and this collar engages with a groove in the crank-case, as shown in the sketch. By this means the cylinders are held in place by the same bolts that keep the two parts of the crank-chamber together. In the sketch accompanying this latter illustration the method of coupling the pistons to the single crank is shown diagrammatically. One of the pistons is coupled up to the crank by a master connecting-rod having an enlarged big- end, to which all the other connecting-rod big-ends are THE ISAACSON ENGINE. of the stationary shaft, and driven from the propeller boss in a similar manner to the arrangement on the Gnome engine* The distributor is mounted in the crank-case on the car burettor side. Sketches illustrating, diagrammatically, the gear mechanism for driving the half-speed propeller on the Isaacson radial stationary engine. For convenience the perspective sketch is shown with the horizontal shaft In a vertical position. hinged, as shown in the sketch. It will be noticed that the crank is balanced by a revolving weight. In two of the other sketches the gear mechanism driving the propeller is illustrated also more or less diagrammatically, and, for convenience, with the shaft shown vertically instead of horizontally. The crank-shaft is fitted with a gear wheel that meshes with two other gear wheels on the shafts of which are further gear wheels meshing with a gear wheel on the propeller boss. This intermediate train virtually forms a pair of lay-shafts similar to those used in the gear box of a motor car, and the normal gear reduction afforded thereby is two to one. An additional supplementary train of gears, operated from one of the lay-shafts, drives an in ternally toothed ring, on the exterior of which are the cams that operate the valves. Yet another sketch shows (diagrammatically) the pipe work and the principal wiring in the general arrangement of the Isaacson engine on an aeroplane. As the only re volving member is the propeller, which is driven at half speed, it is possible to have a stationary external shaft as well as a stationary engine, and it is through the stationary shaft supporting the propeller that the principal pipes are led to the engine, as shown in the sketch. The petrol is fed from a tank under pressure to a White and Poppe carburettor attached to the cover of the crank-case, and seven induction pipes of equal length distribute the mixture to the cylinders. Oil for lubricating purposes is pumped under pressure to the cranks and up the connecting-rods to the gudgeon-pins. The oil pump and the magneto are disposed on opposite sides Sketches illustrating the method of fastening the cylinders to the crank-case and the connecting-rods to the crank in the Isaacson radial stationary engine. Diagrammatic sketch illustrating the manner in which the fuel-pipes and oil-pipes are arranged on the Isaacson radial stationary engine. The 100-h.p. Isaacson engine. 361
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