Balloons, Airships, and Flying Machines

by Gertrude Bacon

So long as a balloon sails only with the breeze it offers no resistance to the force of the wind, and can be made of the lightest and thinnest material. But directly it has to face the wind, and fight its way against it as an airship must do, then it has to be made of sufficient strength and rigidity to withstand the wind’s power, or it will be blown to pieces. To make so large a thing as an airship withstand a rough wind, it must be built of very strong and rigid materials. To do this means to add to the weight of the machine. To lift the increased weight, a larger machine which can hold more gas is needed. The larger the machine the more surface it offers to the wind, and the stronger therefore must be its construction. It will now be seen that we are arguing in a circle, and we can understand that a point must be reached in the making of airships when, with our present materials, the advantage gained by increase of strength will be more than counterbalanced by increased weight. On this point Sir Hiram Maxim says: “It is not possible to make a balloon, strong enough to be driven through the air at any considerable speed, at the same time light enough to rise in the air; therefore balloons must always be at the mercy of a wind no greater than that which prevails at least 300 days in the year;” adding, “Those who seek to navigate the air by machines lighter than air have, I think, come practically to the end of their tether.”

With the flying machine, on the contrary, the same difficulty does not arise. Since it is at all times heavier than air, and is kept aloft simply by its motive power and mechanism, its weight is of no consequence, provided only its engine is sufficiently powerful. It may, therefore, be built as rigidly as need be, while, from its size—which is much smaller in proportion to its lifting power than in the case of the airship—and also from its construction, it is much less liable to be affected by the wind.

In constructing a flying machine which is heavier than air the inventor has before him two examples of bodies which, though heavier than the atmosphere, yet contrive to rise upwards into the sky; these are, firstly, birds, and secondly, the familiar schoolboy toys, kites. To imitate the flying powers of birds and kites, he must first understand the means by which their flight is accomplished; and he will find, on examination, that to a large extent the same principle underlies each—the principle of what is termed the “aeroplane.”

Kestrel.

As we watch birds—especially large birds, as hawks and gulls—winging their way about the sky, we may notice that their flight is accomplished in two ways; either they are moving through the air by flapping their wings up and down, or else with wings wide outstretched they are soaring or sailing in the air for long times together without apparently moving their wings at all. Certain birds, such as vultures and albatrosses, possess this power of soaring flight to an extraordinary degree, and the exact way in which they keep themselves poised aloft is indeed still a mystery. We cannot, however, as we watch, say, a hawk, hovering in the air with motionless wing, help being struck by its resemblance to the schoolboy’s kite, kept afloat high in the sky by the action of the wind properly applied to its surface, and we can at once see that the bird makes use of the same principle as the kite in its soaring or hovering flight. Indeed, just as a kite sinks to earth when the wind drops, so in a dead calm even an albatross has to flap its wings to keep afloat.

It is to the principle of the kite, therefore, that the inventor of the flying machine must turn. He must adapt the same principle to his apparatus, and this he does in his aeroplane, which, as will be seen, is an all-important part of his machine, and which, in its simplest form, is nothing more or less than a kite.

We know that if a light flat body, such as a kite, is lying upon the ground, and the wind gets under it so as to tilt it, it will be lifted by the wind into the air. The string of a kite is so adjusted that as the kite rises it is still held at an angle to the wind’s force, and so long as the kite remains tilted at the necessary angle so long it will continue to rise or poise itself in the air while the wind blows. When schoolboys fly their kites they choose an exposed spot, and a day when the wind is blowing freshly and steadily. One boy throws the kite into the air, while another, holding the string to which it is fastened, draws it tight by running with it against the wind. By this means the kite, if rightly adjusted, is held at the proper angle to the wind, and started without dragging along the ground to begin with. As soon as the wind has fairly caught the kite and carried it up into the air, the boy who holds the string need run no longer, but if the breeze suddenly fails, and the kite begins to drop, he may still keep his toy aloft by running quickly along and dragging the kite after him; the artificial wind he thus creates making up for the lack of the other.

Now let us suppose that there is no string to hold the kite in proper position, and no boy to run with it; but that their places are supplied by a motor and propeller to drive it through the air; while at the same time it is so balanced as to preserve a fitting angle against a wind of its own making. We should then have a true flying machine, heavier than air, and yet capable of sailing through the sky.

This is the kind of flying machine that inventors at the present moment are trying to produce. They have, in their machines, to reproduce artificially two essential conditions that cause a kite to fly. They have to provide a substitute for the strength of the wind, and also a substitute for the pull of the string which keeps the kite at the best angle to profit by that strength. The first they achieve by using a suitable engine or motor, and the second by supplying it with what are called “aeroplanes”—large flat surfaces, light but rigid, inclined at a suitable angle to the horizon. By the use of these the power of the engine is employed to best advantage in causing the machine to sail through the sky.