HOW TO MAKE A SCIENTIFIC KITE.
It is important, then, to know how to make a scientific tailless kite, such as is used by the experts at the Smithsonian Institution, or at the Blue Hills Conservatory near Boston, for it must not be supposed that kite-flying is merely an idle pastime; it is a pleasure doubtless for boys, but it is also a field of serious experiment and observation for men. The information I here present, including practical directions as well as interesting theories, was obtained from Mr. Eddy himself, and may be regarded as strictly accurate.
Frankfort Street. PHOTOGRAPHIC VIEW FROM A KITE.
This view, from a photograph taken from a kite by Mr. W.A. Eddy, New York City at the crossing of Frankfort and William Streets.
It is much better for amateurs to begin with a kite designed to fly in strong winds, as it is a long and delicate task to learn to manage the variety with extra wide cross-stick meant for ascension in calms. The two sticks which form the skeleton should be of equal lengths, say six feet; and should cross each other at right angles at a point on the upright stick eighteen per cent. of its length below the top. This point of crossing is of great importance, and was only located by Mr. Eddy after months of wearisome experiment. He was misled in his earlier efforts at tailless kite-making by the example of the Malay kiter-flyers, who are reputed to be the most skilful in the world, and who cross the sticks much nearer the middle of the upright one. In a six-foot kite the two sticks, equal in length, should cross at about thirteen inches from the top of the upright stick; and the same proportion should be observed for kites of other dimensions. At the point of crossing, the sticks should be slightly notched, and strongly bound together with twine tied in flat knots. Driving a nail or screw through the sticks, to bind them, weakens the frame at the point of greatest strain.
As material for the sticks Mr. Eddy has found clear spruce better than any other wood. Bamboo is bad, because it bends unevenly at the joints. White pine is not tough enough, and cypress is both too brittle and too flexible. The hard woods, like ash, hickory, and oak, are too heavy; in scientific kite-flying, even so small a weight as a quarter of an ounce may make all the difference between failure and success. All winds are broken by frequent brief intervals of calm, and a kite must rely on its lightness to outride these. Whoever contemplates going seriously into kite-flying will do well to provide himself with a store of suitable sticks by purchasing a straight-grained, well-planed spruce plank, free from knots, and having it sawed on a circular saw into sticks five-sixteenths and seven-sixteenths inches in thickness, to be cut later into such lengths as he may choose.
Frankfort Street. PHOTOGRAPHIC VIEW FROM A KITE.
From a photograph taken from a kite by Mr. W.A. Eddy. This view also is of New York City about the crossing of Frankfort and William Streets. The high wall on the right of Frankfort Street is the back of the "World" building; the high wall on the left is the back of the "Tribune" building.
The two sticks (there are never more than two) having been fastened firmly together, the cross-stick must be sprung backward; so that, when finished, the kite will present a convex or bulging surface to the wind. It might be imagined that a concave surface to the wind would be better; and indeed this has been tried. But it has invariably proved that with a concave surface the kite receives too much of the breeze and becomes quite uncontrollable. The amount of spring that must be given the cross-piece is in proportion to its length, Mr. Eddy's rule being to spring the cross-stick, by means of a cord joining the two ends like a bow, until the perpendicular between the point of juncture of the two sticks and the centre of the cord is equal to one-tenth of the length of the cross-stick, or a little more than one-tenth, if the kite is to be flown in very high winds.
It is of the first importance to keep the two halves of the kite on the right and the left of the upright stick perfectly symmetrical. And this is by no means an easy matter. It often happens in bending the cross-stick that, owing to differences in the fibre and elasticity of the wood, one side bends more than the other, with the result that the two halves present different curves and consequently unequal wind areas. To offset this difficulty, and also to strengthen the skeleton, Mr. Eddy's practice is to add a bracing piece at the back of the cross-stick—a piece about one-fourth of the length of the cross-stick itself, and of the same width and thickness. If the two halves of the kite are already quite symmetrical, he places this bracing stick with its centre directly even with the point of juncture of the two large sticks, its two ends being fastened with twine to the cross-stick, about nine inches on either side of the crossing-point. But if one half of the cross-stick shows a greater bend than the other, he places the longer arm of the bracing piece toward the side that bends the most, thus presenting a greater leverage against the wind on that side than on the other, and so equalizing things.
With the two sticks and the brace all thus properly in place, a supporting frame for the paper or cloth is formed by running, not cord, but fine picture wire, over the tips of the sticks, notched to hold it in place, in the ordinary way. Then, with a thin, clear paste made of starch, the paper may be laid on, care being taken to paste the edges so as to leave a certain amount of slack or looseness in the part of the kite below the cross-stick, so that each of the lower faces will present concave wind surfaces. To preserve the required equilibrium, it is important that the amount of looseness in the paper be equal on the two sides; and in order to keep it so, it is necessary to measure exactly the amount allowed.
THE EDDY TAILLESS KITE.
Front view, showing how the line is attached.
A storm-flyer.—The diamond-shaped figure in the centre is an opening made to lessen the wind pressure.
Those who wish to make many kites will do well to buy thin manilla paper, as wide as possible, having the dealer roll off for them seven hundred or eight hundred feet, say a yard in width, which will insure a cheap as well as an abundant supply. For strong winds and large kites it is best to use cloth as the covering. It should be sewed to the frame, and, if carefully put on, will do service for years. Silk, of course, is the ideal material; but its costliness puts it beyond ordinary means, and common silesia, such as is used in dress linings, is almost as good. Whatever the material, the kite should be fortified at the corners by pasting or sewing on quadrants of paper or cloth, so as to give double thickness at the points most liable to injury. A finished six-footer should not weigh over twenty ounces, if covered with paper; or twenty-five ounces, if covered with cloth. Mr. Eddy has made a six-footer for calm flying as light as eight ounces.