On the Farman aeroplane, the arrangement for providing stability is very interesting. The ailerons in this case are attached to the rear of one of the main planes, the lower one, by hinges. This general plan will be followed in the case of the model aeroplanes. In a number of successful model aeroplanes, the Farman ailerons have been closely imitated. The Curtiss biplane depends for its stability upon ailerons mounted midway between the two main planes and partly within them. This plan is scarcely practicable in the case of model aeroplanes, since they increase air resistance and are difficult to control.
The Baldwin biplane has introduced a new feature for obtaining stability which may be closely imitated. A large plane is set vertically, directly above the upper main plane which may be swung from side to side by the pilot. The theory of this stabilizing surface is that it will restore equilibrium from side to side, since it works in undisturbed air while meeting with very little head resistance.
Many builders of model aeroplanes have introduced a similar vertical plane directly above the main plane, or have placed it well forward at the extreme front of the motor base. By removing this rudder as far as possible from the main supporting surface, it exerts a greater leverage, and a very small plane carried well forward will be more effective than a larger plane directly above the main supporting surface. It has the disadvantage of catching any chance side current and thereby knocking the aeroplane off its course.
Percy Pierce, winner of the distance record
A well-proportioned model, capable of long flights
A well designed aeroplane built by James MacPherson
The same principle has been carried somewhat further in the case of the new Herring biplane, which carries six triangular stabilizing fins set vertically above the upper plane. It is believed that these fins offer considerable resistance to any tipping motion of the planes, and if the machine slants to one side or the other, for any cause, there is a tendency, of course, to dart downward at an abrupt angle. The fins retard this motion as far as the upper plane is concerned, and the lower plane without such an equipment tends to swing back like a pendulum, thus bringing the aeroplane to an even keel.