WHY AN AEROPLANE FLIES.

Northern Advocate, 19 January 1920, Page 4

WHY AN AEROPLANE FLIES.

(By Norman Clark, late Lieut. R.A.F)

The average person on seeing an aeroplane soar gracefully into the sky has doubtless wondered why it is that it stays there, and does not fall to the earth, as other bodies do.

The first thing to grasp in the understanding of flight is that air has a lifting power similar to that of water only air is lighter.

Now, if you place your hand under water # and, tilting it slightly upward drag it along level with the surface, you will notice that it has a tendency to rise. Similarly, if you take a piece of paper, hold it at a slight angle, and drag it quickly through the air, you will observe that it also tends to rise. The faster you move it, the more it rises. This simple fact forms the basis of aeroplane flight.

The reason the piece of paper acts as it does is two fold. Firstly t because the inclined surface has a tendency to glide on the air underneath it; secondly, because in cutting its way through the air it has displaced some of the air above it, and thus caused the air underneath to rush up and take its place.

Above the inclined plane a vacuum is created; 'below it is the air on which it glides, and which is endeavouring to rush up and fill the vacuum above. The result is that the plane is forced upwards. Such is the principle of flight.

WHY THE 'PLANE GLIDES. In place of the piece of paper, there are wings consisting of air tight fabric. These wings are so constructed that they do not only glide on the air beneath, but also displace the air above them.

They glide on the air beneath them because they are set at which is termed an "angle of incidence" which means that they are slightly inclined to the air they are meeting. The displacement of the air above is increased by constructing the planes so that the upper surface is curved, and thicker towards the front than the rear.

When the speed at which the wings are passing through the air becomes sufficient to enable the "lift" created to overcime the counteracting force of the machine has "flying speed." Hence, the first thing necessary in order to rise from the ground is for the machine to hava sufficient run to attain "flying speed." Aeroplanes are so constructed that when the engine is running full out, the forces of gravity and lift are pulling directly against each other. When the engine is stopped the centre of gravity falls slightly in front of the centre of ilf-t, thus permitting the machine to assume a gliding angle. It is thus enable-d to land without losing flying speed and with a maximum forward travel in proportion to the height lost—in most machines about ten feet forward to every one foot descent,

In the course of :t debate in London on venereal disease Canon Ilorsely paid he believed much evil was done by lovels. An incentive to immorality was given by many of those recently published. At a meeting of Lh" Bay of Islands R.S.A. executive, th e following remit from Kaikohe was passed nem con: _" That the Bay of Islands R.S.A. views with alarm the unprogressivc methods of the Railway Department. That in the interests of the North, and of this country in particular, th e Railway Department be urged to establish a daily train service on the Kaikohe-Otiria line forthwith. All trains to run through to Opua. Also, that th c Department be requested to run a fast passenger train on Manaia days. The present slow train is against progress. The Bay of Islands R.S.A. suggests that they approach the County Council and the Kaikohe and Kawakawa Town Board re them passing similar resolutions, and that copies of same be forwarded to the District Manager, Railway Department, Whangarei, and the member for the district (Mr V. H. Reed). A resolution similar to the above has been passed by the Kaikohe. Farmers' Union and ratepayers."