Page:Aerial Flight - Volume 2 - Aerodonetics - Frederick Lanchester - 1908.djvu/26

§ 2 discussion, including an account of the author's earlier (1894) experiments.

'''§ 3. The Ballasted Aeroplane. A Simple Case.'—The simplest construction of flight model known is that described in §§ 162, 241, et seq., of the author's "Aerodynamics," under the title of the Ballasted Aeroplane''. If an aeroplane of about the proportions shown in Fig. 1 be loaded by appropriately disposed ballast, to bring its centre of gravity to a point somewhere about one-quarter of its width from the leading edge, it is found to be capable of gliding flight and is stable both laterally and longitudinally within certain limits.

For experimental purposes the author has found a mica plate about 2 inches by 8 inches by about three to four thousandths of

Fig. 1.

an inch thick, gives the most satisfactory results, the ballast taking the form of a split lead shot secured by closing on to the leading edge of the mica plate at a point midway between its ends.

The ballasted aeroplane constructed as described is easily upset by any sudden puff of wind, but in still air, as when experimenting inside a building, it may be employed to demonstrate many important points relating to the equilibrium question. A ballasted aeroplane may be launched directly by hand, the mica plate being taken between the finger and thumb and projected forward with as nearly a parallel motion as possible. A better way is to employ a launching staff, Fig. 2, which consists of a straight rod a few feet in length, capped with a small rectangular platen on which the aeroplane is carried; the