THE REEFING AEROPLANE.

Evening Post, Volume LXXXI, Issue 83, 8 April 1911, Page 10

THE REEFING AEROPLANE.

The speed of. the aeroplane has reached a point at which the need is felt for some system of "reefing," by which tho area of the supporting surfaces can be varied to suit the various speeds afc which the machine may be flying. This demand for a variable surface is due to one of the most important of the laws of flight; namely, that the area of tho necessary supporting surface of an aeroplane varies inversely as the square of the velocity. This principle, affirmed by Langley and embodied in his great work "Experiments in Aerodynamics," has been disputed by some American theorists and practical aeroplane builders; but the- experience .of tho last two years seems to verify it. If the law hold good, the standard Wright aeroplane, which, with about 500 square feet of surface, has a speed of 40 miles per hour, at 60 miles would need only 222 square feet for support, and at 100 miles per hour, only 80 square feet. Now, that the law is generally correct, or, at least, that it does not produce too great a reduction of surface, is shown by the two very interesting racing machines exhibited and flown by the Wright Brothers at Behnont Park last autumn. One of these, a semiracer, with a speed of 60 miles an hour, was provided with only 160 square feet of sustaining surface. Tlie standard Wright machine, driven at 60 miles an hour, would need, according to the law, 222 square feet of surface. Its weight, however, with operator and full fuel and water supply, is 1075 pounds; whereas the 60-miie semi-racer weighs with operator and fuel only 760 pounds. The difference in weight 'would largely account for the reduction of the area of the 60-mile racer from 222 down to 150 square feet. Further verification of the law is found in the Bleriot racer -which, with slightly less speed, and a weight of 650 pounds with operator, also has but 150 square feet *of sustaining surface. It is significant that in the actual racing machine, which is 15 miles an hour faster, the Wrights diS not venture to reduce the supporting surface any further, both the semi-racer and the racer having 150 square feet of surface. The racer, however, is heavier, weighing, with operator and fuel, about 900 pounds. If, then, the high speed fliers of 1910 have endorsed the Langley law, ifri follows that there will be a still further reduction of area in the racing machines of the future. If the standard Wright machine, with 500 square feet of surface, could be driven at 100 miles an hour, it woidd need only 80 square feet of surface for support, and if a speed greater than 100 miles per hour were accomplished, the sustaining surface would come down to a, pair of lonp narrow blades, approximating in form to the wings of the swift Or the swallow. But ifc must be remembered that these reduced surfaces ar« equal to their work only if the machine is beine driven at its highest, or at least at a high velocity; and they are therefore theoretically too small to lift the machine from tho ground or allow it to return safely thereto at the lower speeds which are necessary in starting and alighting. Proof of this was shown in the accident which disabled the Wright racing machine at the time of the contest at Belmont Pa.rk for the international trophy, when the stopping of the motor and the sudden slowing down of tho biplane caused the machine tn drop so -swiftly to the ground that its momentum partially wrecked the machine and threw the aviator from his S T\ Pi ; obab ly» having been accustomed to tho larger-surface Wright machine, he did not realise that he should descend . with hU main planes at a large angle of incidence in order to check the velocity. In any case, it is ■evident that, if the racing aeroplane a speed of 100 miles an hour, it will be necessary, for safe control, to provide it with some means for enlarging or reducing the supporting area proportionately to tho speed. The problem should not be so very dfficult of solution. The additional surface could be arranged to be drawn ivnaer or within the main surfaces either from the ends or from the rear. If, as wo believe, the machines of the futuve will be built entirely of metal, the problem will be jio much the easier to work oi^>; but it should not be impossible to arrange some system of "reducing canvas" in the present type of machine, by drawing the furled surface* into such a form that they will , not offer any material head resistance. A large percentage or tne accidents to the existing machines are due to descending and landing at too great an angle or at too g_reat a speed. Were it possible, voluntarily to increase- the surface at the time of making a landing, the risk of accident from this cause would be largely reduced. — Scientific American.

She — They say that an apple a day will keep the doctor away. He— Why stop there? An onion a day will keep everybody away.