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Aviation History
1909
1909 - 0238.PDF
APRIL 24, 1909. course of time this material is liable to shrink and become brittle, although it is impervious to the wet during its life. Brown Paper: Canvas-backed packing paper about 24 standard wire gauge, has a weight of $ of an oz. per sq. ft. The canvas is of the lightest description, but will not separate unless wet, and the material is very useful for experimental work as it does not easily tear. Oiled Canvas, Linen, &c: The weight runs from if ozs. to 2"6oz. per sq. ft. The material is reliable in wet weather and high winds. Willesden Canvas: Costs about 2s. per yard, and is very useful on account of its durability in bad weather. Proof Silk: Weighs -34 of an oz. per sq. ft., and can be obtained in rolls about 5 ft. wide at about 2^d. per sq. ft. Proof Cotton Sheeting can also be obtained, but is heavier. A CENTURY AGO. SIR GEORGE CAYLEY AMONG the models exhibited at Olympia was, as we mentioned in last week's issue, one which the Aero Club had had constructed as a copy of the Henson-Stringfcllow model in the South Kensington Museum. Appended to the model was the following very interesting notice, which not only describes an inventor's ideas of a hundred years ago, but also pays fitting tribute to Sir George Cayley who, of all early scientists, made perhaps the most profound study of flight, thereby enrolling his name in this country honourably in the list of those who first extended their mental vision to include the conquest of the air within the boundaries of science :— "Flight" Copyright Photo. Over sixty years ago Henson and Stringfellow constructed the model mono- plane, of which the above is a copv, belonging to the Aero Club. The original is in the South Kensington Museum. " This year, 1909, is the centenary of the appearance in Nichol- son's Journal and the Philosophical Magazine of some remarkably able articles on flight by an English scientist, Sir George Cayley. His insight into the problem of aviation was profound, but neither his own generation nor his successors realised his merit, for he was so much in advance of his time that it has needed an interval of a hundred years to demonstrate the truth of his assertions. " France has not hesitated to do him justice, and M. Tatin, writing in the Elements d1 Aviation, has said :— " ' It would be difficult to construct a machine to-day which did not embody the majority of the features indicated by Cayley. His contributions to the theory of flight form a work of reference which it is well not to ignore.' " Much earlier, in 1874, another Frenchman, M. Penaud—himself well known as a pioneer in flight—paid a special visit to England on purpose to make research among Cayley's writings, and on his return to France he presented his discoveries in eulogistic terms before a meeting of the Societe Francaise de Navigation Aerienne. " Sir George Cayley seems to have appreciated almost every side of the problem of aerial navigation. He foresaw the difficulties associated with dirigible balloons on account of their enormous size, but he pointed out how they might be made to ascend and descend in the air without loss of ballast. " In 1796 he constructed a model helicopter with a pair of lifting screws revolving in opposite directions, and expressed his conviction that it would be possible for a full-sized man-lifting machine to be ON FLIGHT IN 1809. made on these lines. He anticipated the advent of aeroplanes, and, knowing that great lifting effect could be obtained from surfaces moving through the air at slight inclinations to the horizontal, he pointed out the importance of carrying out what are now known as ' lift and drift' experiments. He suggested the use of a tail as a means of obtaining automatic longitudinal stability in aeroplanes, and he further showed how the pivoting of that tail would enable it to be used as an elevator for ascent and descent. He deduced the advantage of wing flexion from his observations of bird flight, and he carried his investigations on the subject of propulsion into a close study of the theory of screws. Having invented a hot-air engine— and that, probably, the first of its kind—he foresaw possibilities in the use of gaseous mixtures, which have since been more than realised in the development of the petrol engine. On the question of steam he was even more precise, for he definitely suggested the use of a tubular boiler and surface condenser, both of which principles are now common in practice. " The time was not then ripe for the realisation of his ideas, but some thirty years later, in 1843, an engineer named Henson drew out designs for a steam-driven monoplane based on Sir George Cayley's data. " A model of Henson's machine, which he constructed in conjunction with Stringfellow, is on exhibition at the South Kensington Museum, and it is a copy of this model, on a smaller scale, which is on view -i; - above. The design was patented in 1842, and is thus officially described in the Museum :— " ' The model consists of an extended surface or aeroplane of oiled silk, or canvas stretched upon a bamboo frame made rigid by trussing, both above and below. A car is attached to the under side of the aeroplane to contain the steam engine, passengers, &c. It has three wheels to run freely upon when it reaches earth. Two propellers, 3 ft. in diameter, are shown :-• , .; with their blades, set at 45 degs. They are operated by endless cords from the engine. Behind these is a fan-shaped tail stretched upon a triangular frame capable of being opened out, closed, or moved up and down by means of cords and pulleys. By this latter arrangement ascent or descent was to be accomplished. A rudder for steering sideways is placed under the tail, and above the main aeroplane a sail (not shown) was to be stretched between two masts rising from the car, to assist in maintaining the course. When in motion the front edge of the machine was to be raised in order to obtain the required air support. To start the model it was proposed to allow it to run down an incline, e.g., the side of an hill, the propellers being first set in motion. The velocity gained in the descent was expected to sustain it in its further progress, the engine overcoming the head resistance when in full flight. Experiments were eventually made on the downs near Chard, and the night trials were abandoned, as the silk became saturated from a deposit of dew. After many day trials, down wide inclined rails, the model was found to be deficient in stable equilibrium for open-air experiments, little puffs of wind or ground currents being sufficient to destroy the balance. The actual machine was never constructed, but in 1847-8 F. Stringfellow built a model which is supposed to be the first flying machine to perform a successful flight. " ' The dimensions of the model shown are 20 ft. from tip to tip of wings, by 3 '5 ft. wide, giving 70 sq. ft. sustaining surface to the wings, and about 10 sq. ft. in the tail. Its weight is about 25 lbs. The actual machine was to weigh about 3,000 lbs., with 4,500 sq. ft. surface in the wings, and 1,500 sq. ft. in the tail."' BACK NUMBERS OF FLIGHT.' THE publishers have pleasure in announcing that they have secured a few of the early issues of FLIGHT, and any of our new readers who may wish to complete their sets may obtain the first sixteen numbers for 2s. post free, from the Publishers, 44, St. Martin's Lane, W.C. 240
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