Fig. 195.—Sectional View Showing Internal Parts of Six-Cylinder Anzani Engine, with Starwise Disposition of Cylinders.
Fig. 196.—The Anzani Ten-Cylinder Aviation Engine at the Left, and the Twenty-Cylinder Fixed Type at the Right.
The Anzani aviation engines are also made in ten- and twenty-cylinder forms as shown at [Fig. 196]. It will be apparent that in the ten-cylinder form explosions will occur every 72 degrees of crank-shaft rotation, while in the twenty-cylinder, 200 horse-power engine at any instant five of the cylinders are always working and explosions are occurring every 36 degrees of crank-shaft rotation. On the twenty-cylinder engine, two carburetors are used and two magnetos, which are driven at two and one-half times crank-shaft speed. The general cylinder and valve construction is practically the same, as in the simpler engines.
CANTON AND UNNÉ ENGINE
This engine, which has been devised specially for aviation service, is generally known as the “Salmson” and is manufactured in both France and Great Britain. It is a nine-cylinder water-cooled radial engine, the nine cylinders being symmetrically disposed around the crank-shaft while the nine connecting rods all operate on a common crank-pin in somewhat the same manner as the rods in the Gnome motor. The crank-shaft of the Salmson engine is not a fixed one and inasmuch as the cylinders do not rotate about the crank-shaft it is necessary for that member to revolve as in the conventional engine. The stout hollow steel crank-shaft is in two pieces and has a single throw. The crank-shaft is built up somewhat the same as that of the Gnome engine. Ball bearings are used throughout this engine as will be evident by inspecting the sectional view given at [Fig. 199]. The nine steel connecting rods are machined all over and are fitted at each end with bronze bushings, the distance between the bearing centers being about 3.25 times crank length. The method of connecting up the rods to the crank-pin is one of the characteristic features of this design. No “mother” rod as supplied in the Gnome engine is used in this type inasmuch as the steel cage or connecting rod carrier is fitted with symmetrically disposed big end retaining pins. Inasmuch as the carrier is mounted on ball bearings some means must be provided of regulating the motion of the carrier as if no means were provided the resulting motion of the pistons would be irregular.