Sectional drawings showing details of construction of the Anzani motor. The flanges of the air-cooling system are distinctly shown. The section at the left is from the side; that at the right, from the front. All measurements are in millimètres. A millimètre is 0.039 inch.
The great rivalry of the builders of motors has been in cutting down the weight per horse-power to the lowest possible figure. It goes without saying that useless weight is a disadvantage in an aeroplane, but it has not been proven that the very lightest engines have made a better showing than those of sturdier build.
The “Gobron” engine of the “double opposed,” or cross-shaped type. A water-cooled engine, with 8 cylinders.
One of the items in the weight of an engine has been the fly-wheel found necessary on all motors of 4 cylinders or less to give steadiness to the running. With a larger number of cylinders, and a consequently larger number of impulses in the circuit of the propeller, the vibration is so reduced that the fly-wheel has been dispensed with.
The Emerson 6-cylinder aviation engine, of the “tandem” type, water-cooled; 60 horse-power; made at Alexandria, Va.
There are several distinct types of aircraft engines, based on the arrangement of the cylinders. The “tandem” type has the cylinders standing upright in a row, one behind another. There may be as many as eight in a row. The Curtiss and Wright engines are examples. Another type is the “opposed” arrangement, the cylinders being placed in a horizontal position and in two sets, one working opposite the other. An example of this type is seen in the Darracq motor used on the Santos-Dumont monoplane. Another type is the “V” arrangement, the cylinders set alternately leaning to right and to left, as seen in the “Fiat” engine. Still another type is the “radiant,” in which the cylinders are all above the horizontal, and disposed like rays from the rising sun. The 3-cylinder Anzani engine and the 5- and 7-cylinder R-E-P engines are examples. The “star” type is exemplified in the 5 and 7-cylinder engines in which the cylinders radiate at equal angles all around the circle. The “double opposed” or cross-shaped type is shown in the “Gobron” engine. In all of these types the cylinders are stationary, and turn the propeller shaft either by cranks or by gearing.
The Elbridge engine, of the “tandem” type and water-cooled. It is an American engine, built at Rochester, N. Y.