Page:Aerial Flight - Volume 2 - Aerodonetics - Frederick Lanchester - 1908.djvu/45

Rh The tail-plane is of triangular form, and has an area = .20 sq. ft., its function is purely directive. The tail-plane has the same function as is performed by the change in the position of the centre of pressure of the ballasted aeroplane; it preserves

Fig. 18.

the constant attitude of the aerodone in relation to its line of Right, in this respect its action being analogous to the feathers on an arrow.

The distance between the centres of pressure of the aerofoil and tail-plane is 3.9 feet approximately.

Two fins, sections H and J (Fig. 20), are provided, of the

Fig. 19.

form shown in Fig. 15, whose area is approximately .2 sq. ft. and .3 sq. ft. respectively. These have for their function the maintenance both of lateral and directional equilibrium, and their action is represented in the ballasted aeroplane by the