the main plane will vary under different air conditions, sometimes being placed over the separator C, and at other times closer to separator B than is shown in Fig. 35. Therefore, you must adjust your plane and elevator—this operation is known as tuning—to suit the condition of the atmosphere, until you find the positions where they will give the machine the greatest stability. A great factor
Fig. 40.—Detail of the Main Plane Framework of the Wells Model.
Fig. 41.—Detail of the Elevator Framework.
Fig. 42.—Detail of Fin.
in the successful flight of a model aeroplane lies in properly tuning the planes, both laterally and longitudinally, and of course the planes must balance at their centers, in order to make the machine balance properly.
The Fin directly over the center of the elevator (Figs. 34 and 36) is provided for stability, and may be used as a rudder by turning it slightly to one side or the other. It is made of No. 34 gauge sheet aluminum, cut to the form
