In a number of airplanes of the tractor-biplane type the power plant installation is not very much different than that which is found in automobile practice. The illustration at [Fig. 145] is a very clear representation of the method of mounting the Curtiss eight-cylinder 90 H. P. or model OX-2 engine in the fuselage of the Curtiss JN-4 tractor biplane which is so generally used in the United States as a training machine. It will be observed that the fuel tank is mounted under a cowl directly behind the motor and that it feeds the carburetor by means of a flexible fuel pipe. As the tank is mounted higher than the carburetor, it will feed that member by gravity. The radiator is mounted at the front end of the fuselage and connected to the water piping on the motor by the usual rubber hose connections. An oil pan is placed under the engine and the top is covered with a hood just as in motor car practice. The panels of aluminum are attached to the sides of the fuselage and are supplied with doors which open and provide access to the carburetor, oil-gauge and other parts of the motor requiring inspection. The complete installation with the power plant enclosed is given at [Fig. 146], and in this it will be observed that the exhaust pipes are connected to discharge members that lead the gases above the top plane. In the engine shown at [Fig. 145] the exhaust flows directly into the air at the sides of the machine through short pipes bolted to the exhaust gas outlet ports. The installation of the radiator just back of the tractor screw insures that adequate cooling will be obtained because of the rapid air flow due to the propeller slip stream.
Fig. 146.—Latest Model of Curtiss JN-4 Training Machine, Showing Thorough Enclosure of Power Plant and Method of Disposing of the Exhaust Gases.
Fig. 147.—Front View of L. W. F. Tractor Biplane Fuselage, Showing Method of Installing Thomas Aeromotor and Method of Disposing of Exhaust Gases.
INSTALLATION OF CURTISS OX-2 ENGINE
The following instructions are given in the Curtiss Instruction Book for installing the OX-2 engine and preparing it for flights, and taken in connection with the very clear illustration presented no difficulty should be experienced in understanding the proper installation, and mounting of this power plant. The bearers or beds should be 2 inches wide by 3 inches deep, preferably of laminated hard wood, and placed 115⁄8 inches apart. They must be well braced. The six arms of the base of the motor are drilled for 3⁄8-inch bolts, and none but this size should he used.
1. Anchoring the Motor. Put the bolts in from the bottom, with a large washer under the head of each so the head cannot cut into the wood. On every bolt use a castellated nut and a cotter pin, or an ordinary nut and a lock washer, so the bolt will not work loose. Always set motor in place and fasten before attaching any auxiliary apparatus, such as carburetor, etc.