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Aviation History
1910
1910 - 0062.PDF
pis JANUARY 22, 1910. DESIGN AND CONSTRUCTION OF AEROPLANES.* By J. P. CHITTENDEN and L. H. ROBINSON. IT is the desire of the authors in placing this paper before the Society, not only to give the results of their own and others' experiments in the design and construction of aeroplanes, but also to afford an opportunity of discussing a subject which now holds a prominent part in the minds of those interested in the science of aviation. There is no doubt that in the earliest times this science com manded man's attention, but not until the last three years can it be said that man has actually achieved flight with machines heavier than air, although, previous to this, machines have been made which have risen from the ground, the most notable being that of Adder in 1890, with a steam-driven mono- FlG. 1. FIG. 2. plane weighing 1,100 lbs. and 54 ft. across the tips of the wings. The engine is worthy of note, it being a 4-cylinder compound, weighing 70 lbs., and said to have developed 25-h.p. The trials of the machine were conducted secretly, so that very little definite information of its performances is to be had, but it is reported to have flown several hundred yards. The early experiments of Otto Lilienthal in 1891 to 1896 with his gliders ; Prof. Langley with his large power-driven model; Sir Hiram Maxim in 1893 wifn the largest machine which perhaps has ever been built, certainly led the way to those more recent experi menters who have brought the knowledge they obtained to a practical issue. The total lifting surface of Sir Hiram Maxim's machine was 6,000 sq. ft., the horse power of the steam engine being 360. With three men on board the weight was about 8,000 lbs. This machine was tried on a specially prepared track fitted with guard rails, and undoubtedly lifted, as these rails were torn away, causing the machine to be severely damaged. It was a great loss to aviation that Sir Hiram Maxim did not continue his valuable experiments in this direction, as the thorough way in which he attacked the problem in its early stages, and the careful manner in which he collated data, would, if carried on, have given to mankind a valuable foundation for future work. Santos Dumont, on October 23rd, 1906, with a machine con structed by a French firm, flew 200 ft. at a height of 6 to 7 ft. from the ground. The machine was of the box form, and the main planes were set at a dihedral angle ; but it remained for Farman, in January, 1908, and Wright, in August, 1908, to prove that heavier- than-air machines could be made to fly and manoeuvred satisfactorily. It is probable that this result would have been achieved sooner had a light form of petrol motor been obtainable. As the subject of aviation is a large one, the authors of this paper have decided to confine themselves to aeroplanes in the more strict sense, that is to say, machines with one or more planes that are fixed, except for the purpose of control, driven by a self contained motor ; this naturally excludes all types of helicopeters and orthopters. Aeroplanes may be divided into two types, namely, monoplanes, an example of which is Bleriot's machine, and multiplanes, of which the Wright and Voisin are the most common. The latter may be divided into two classes, those which aim at natural lateral stability, and those which rely on mechanical movements to obtain lateral stability. Monoplanes,—Fig. i shows the general outline of a monoplane. A. Being the main wings, which are in all cases double-covered. B. The body; this being made up in the form of a lattice girder of box section, of wood struts and wire ties, and is usually encased in fabric to reduce air friction. When water-cooled engines are used, the radiators are in most cases placed along the side of the body. C. The elevator is placed at the back of the machine, and in conjunction with the rudder, d, forms a tail. It is probable that before long the vertical plane may be dispensed with, and side steering effected by movement of the wings alone. Multiplanes,—Under this heading will be dealt with the most common form, namely, the biplane, which is shown in Fig. 2. A. Main planes; both the single and double- covered method is employed, the planes being superposed and braced in the form of a lattice girder. R The elevator is usually constructed in a similar manner to the main planes. Although the initial function of the elevator is to assist in raising the machine from the ground, in actual flight it is used principally to damp longitudinal oscillations, the actual elevating being usually accomplished by varying the speed of the engine. C. The tail seems to be an accessory of doubtful utility, except in the Voisin type, where it is made of box form. D is a vertical plane in line with rudder, E, to assist in directional steering. F. Ailerons, which are used to obtain lateral stability, and take the place of flexing the main planes. Having described the general forms of heavier- than-air machines, attention will now be given to the design and construction of the various parts in detail. Planes.—Of all the parts of latter day machines, the planes or lifting surfaces are perhaps the most near perfection. To Otto Lilienthal and Horatio Phillips we owe the aerocurve or curved plane, which has enabled a greater reduction to be made in the necessary lifting area than if a flat surface was employed. C x -- 0 FIG. 3. In Figs. 3 and 4 are illustrated the most common forms of planes designed on this principle. Fig. 3 is a view of a single-covered plane ; Fig. 3A showing the more correct construction, as this allows the aif- to have a free run on the lower surface. Fig. 4 is a view * Paper read before the Rugby Engineering Societjv showing the section of a double-covered plane. This is undoubtedly the better form, as the frictional losses are greatly reduced, although the mechanical construction is somewhat more complicated than with the single covering. To consider the design 01 these planes on a purely mathematical basis is an utter impossibility. It has been proved repeatedly by 58
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