It is decidedly smaller in area of surface than the Wright and Voisin machines, having but 430 square feet in the two supporting planes. It has a spread of 33 feet, and the planes are 7 feet wide, and set 6 feet apart. In the Farman machine the vertical curtains of the Voisin have been dispensed with. The forward elevator is there, but raised nearly to the level of the upper plane, and placed 9 feet from the front edge of the main planes. To control the equilibrium, the two back corners of each plane are cut and hinged so that they hang vertically when not in flight. When in motion these flaps or ailerons stream out freely in the wind, assuming such position as the speed of the passing air gives them. They are pulled down by the pilot at one end or the other, as may be necessary to restore equilibrium, acting in very much the same manner as the warping tips of the Wright machine. A pair of tail planes are set in parallel on a framework about 20 feet in the rear of the main planes, and a double rudder surface behind them. Another model has hinged ailerons on these tail planes, and a single rudder surface set upright between them. These tail ailerons are moved in conjunction with those of the main planes.
The Farman biplane, showing the position of the hinged ailerons when at rest. At full speed these surfaces stream out in the wind in line with the planes to which they are attached.
Diagram of the Farman biplane. A later type has the hinged ailerons also on the tail planes.
The motor has 4 cylinders, and turns a propeller made of wood, 8 feet 6 inches in diameter, at a speed of 1,300 revolutions per minute—nearly three times as fast as the speed of the Wright propellers, which are about the same size. The propeller is placed just under the rear edge of the upper main plane, the lower one being cut away to make room for the revolving blades. The motor develops 45 to 50 horse-power, and drives the machine at a speed of 41 miles per hour.
The “racing Farman” is slightly different, having the hinged ailerons only on one of the main planes. The reason for this is obvious. Every depression of the ailerons acts as a drag on the air flowing under the planes, increasing the lift at the expense of the speed.
Sketch of Farman machine, showing position of operator. A, A, main planes; B, elevator; C, motor; P, tail planes.
The whole structure is mounted upon skids with wheels attached by a flexible connection. In case of a severe jar, the wheels are pushed up against the springs until the skids come into play.