The Aeroplane

by Claude Grahame-White; Harry Harper

Fig. 5.—Henson’s proposed Machine.

Explaining his theories in this same specification he wrote:

“If any light and flat or nearly flat article be projected or thrown edgewise in a slightly inclined position, the same will rise into the air till the force exerted is expended, when the article so thrown or projected will descend; and it will readily be conceived that, if the article so projected or thrown possessed in itself a continuous power or force equal to that used in throwing or projecting it, the article would continue to ascend so long as the forward part of the surface was upwards in respect to the hinder part.”

Had Henson been able to carry out his ideas, it is almost certain that this experimental machine would have been wrecked in its tests, and probably several more after it, seeing that he would have had to learn to control them when in flight, and remembering also that, even with aircraft as they are built to-day, many details have to be studied and improved before a successful model is evolved.

All such work, of course, entails heavy expense. It was, indeed, the cost of experiments which prevented many an early inventor from building a full-sized machine. The designing and construction of a man-carrying craft, and the employment of skilled workmen and mechanics, to say nothing of repairs that may have to be made during a series of tests, represent an expenditure that may amount to thousands of pounds. As a rule, the inventor is not a man of wealth; and so far as flying was concerned, at any rate in the early days,—and to a more limited extent even at the present time,—people with money thought the difficulties so great that they would not advance funds for the carrying out of trials. So men with ideas had to do the best they could, and this resolved itself generally into writing and lecturing, and endeavouring to interest the public. But the public was not easily interested; ordinary folk did not believe that men would ever fly, while many people declared that it was going against Nature for us to try to imitate the birds, and that nothing but mischief would come of so doing.

Henson, failing to make definite progress with his scheme for a man-carrying craft—despite the fact that a company was floated to assist him—co-operated with another enthusiast named Stringfellow in a plan which was not so elaborate. They began to experiment with a series of models driven by tiny and most ingenious steam engines built by Stringfellow; and so cleverly did he construct them that the Aeronautical Society awarded him a prize of £100. The model which won him this recognition was a little plant which, while it weighed only 13 lbs., without water or fuel, would develop one horse-power.

What, by the way, is meant by a horse-power? The answer is as follows: in the early days of engineering, when it was found necessary to establish some well-recognised unit of power, a large number of experiments were carried out with horses, which were made to raise a weight from the ground by means of an arrangement of pulleys and ropes. The experiments showed this: that a horse can exert sufficient power to raise 33,000 lbs., or about 15 tons, to a height of 1 foot in the space of one minute. This, therefore, was called “one horse-power.”

In Stringfellow’s days, it must be remembered, there was no petrol engine; an engine so extremely light for the power that it will give, and with its liquid fuel and oil carried conveniently in tanks—an engine which, as Sir Hiram Maxim puts it, will give one horse-power of energy “for the weight of a barn-door fowl.”

The question of motive-power was, indeed, the great obstacle for the pioneers. When a man builds an aeroplane he must drive it through the air; and to drive it through the air he requires an engine. But he knows that his planes, owing to the small density or sustaining power of the air through which they pass, will raise only a limited load. And the machine itself, even if it is built of wood and canvas, represents an appreciable weight; to say nothing of that of the pilot. So, if his engine is heavy in proportion to the power it gives, and its fuel weighty, he may be prevented altogether from rising from the ground; or if he does rise, he may be able only to carry sufficient fuel for a flight of a short distance.