Fig. 39.—Aeroplane Model with Automatic Rudder.

a a, Elastic aeroplane.

b b, Automatic rudder.

c c, Aerial screw centred at f.

d, Frame supporting aeroplane,rudder and screw.

e, India-rubber, in a state oftorsion, attached to hookor crank at f. By holdingthe aeroplane (a a) andturning the screw (c c) thenecessary power is obtainedby torsion. (Pénaud.)

D.S. Brown also wrote (1874) in support of elastic aero-biplanes. His experiments proved that two elastic aeroplanes united by a central shaft or shafts, and separated by a wide interval, always produce increased stability. The production of flight by the vertical flapping of wings is in some respects the most difficult, but this also has been attempted and achieved. Pénaud and A.H. de Villeneuve each constructed winged models. Marey was not so fortunate. He endeavoured to construct an artificial insect on the plan advocated by Borelli, Strauss-Dürckheim and Chabrier, but signally failed, his insect never having been able to lift more than a third of its own weight.

Fig. 40.—Pénaud’s Artificial Flying Bird.

a b c d, a′ b′ c′ d′, Elastic wings,which twist and untwistwhen made to vibrate.

a b, a′ b′, Anterior margins ofwings.

c d, c′ d′, Posterior margins ofwings.

c, c′, Inner portions of wingsattached to central shaft ofmodel by elastic bands at e.

f, India-rubber in a state oftorsion, which provides themotive power, by causingthe crank situated betweenthe vertical wing supports(g) to rotate; as the crankrevolves the wings are madeto vibrate by means of tworods which extend betweenthe crank and the roots ofthe wings.

h, Tail of artificial bird.

De Villeneuve and Pénaud constructed their winged models on different types, the former selecting the bat, the latter the bird. De Villeneuve made the wings of his artificial bat conical in shape and comparatively rigid. He controlled the movements of the wings, and made them strike downwards and forwards in imitation of natural wings. His model possessed great power of rising. It elevated itself from the ground with ease, and flew in a horizontal direction for a distance of 24 ft., and at a velocity of 20 m. an hour. Pénaud’s model differed from de Villeneuve’s in being provided with elastic wings, the posterior margins of which in addition to being elastic were free to move round the anterior margins as round axes (see fig. 24). India-rubber springs were made to extend between the inner posterior parts of the wings and the frame, corresponding to the backbone of the bird.

A vertical movement having been communicated by means of india-rubber in a state of torsion to the roots of the wings, the wings themselves, in virtue of their elasticity, and because of the resistance experienced from the air, twisted and untwisted and formed reciprocating screws, precisely analogous to those originally described and figured by Pettigrew in 1867. Pénaud’s arrangement is shown in fig. 40.

If the left wing of Pénaud’s model (a b, c d of fig. 40) be compared with the wing of the bat (fig. 18), or with Pettigrew’s artificial wing (fig. 32), the identity of principle and application is at once apparent.

In Pénaud’s artificial bird the equilibrium is secured by the addition of a tail. The model cannot raise itself from the ground, but on being liberated from the hand it descends 2 ft. or so, when, having acquired initial velocity, it flies horizontally for a distance of 50 or more feet, and rises as it flies from 7 to 9 ft. The following are the measurements of the model in question:—length of wing from tip to tip, 32 in.; weight of wing, tail, frame, india-rubber, &c., 73 grammes (about 2½ ounces).

(J. B. P.)

Flying Machines.—Henson’s flying machine, designed in 1843, was the earliest attempt at aviation on a great scale. Henson was one of the first to combine aerial screws with extensive supporting structures occupying a nearly horizontal position. The accompanying illustration explains the combination (fig. 41).

Fig. 41.—Henson’s Aerostat.