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Aviation History
1909
1909 - 0086.PDF
FEBRUARY 13, 1909. A MODEL WHICH FLEW IN 1893. THERE are few departments of science in which the Hon. C. A. Parsons—whose name as an engineer is so well-known to the public at large on account of his successful develop- ment of the turbine engine—does not take a deep and practical interest; and it will be no surprise to those who know him, to hear that he was conducting experiments with a model flying machine as long ago as 1893. It is of more unexpected interest, however, to know that he Fig. 1.—Steam engine and boiler working lifting screw;large plane to prevent rotation of boiler ; total weight 1J lbs. ; i.h.p. developed J. Raised itself about 12 ft. in theair with steam contained in boiler. No firing after start. Initial pressure 50 lbs. Maximum revolutions about 1,200per minute. actually made an engine-driven model which flew, and that this same model was equipped with a steam engine and a boiler. Although it is impossible at this late date to give any detailed illustrations of this fascinating little toy, we are .enabled, through the courtesy of Mr. Gerald Stoney, who was present on the occasion of the trials, to reproduce a .couple of snapshots which he secured when those trials were in progress. One of them shows the machine tflying in mid-air, while the other represents an earlier model at rest on the ground, getting up steam ready to •fly. The initial experiments were made with a helicopter pure and simple, and it is of this model that the latter illustration was taken. Subsequently, however, the .engine was remounted on the model monoplane having an 11 ft. span, which is shown in flight. In both cases flights were accomplished of a nature which would certainly be •regarded to<lay as of a highly satisfactory character. The principal interest naturally centres in the engine which was capable of performing these feats, and this tmodel was indeed one of those numerous examples in•which Mr. Parsons has shown that it is possible, upon .occasion, to obtain extraordinarily big results from in- stallations of small compass. It requires, however, a practical knowledge of steam, such as is not possessed •by everyone, to know along what lines to commence the .design of such a plant; and yet, as will be seen, the .little model was by no means complicated. It was an outcome of some important experiments in another .direction, and the principal feature consisted in placing tthe engine cylinder, together with its valve, completely inside the boiler so as to avoid loss of heat. As a document of considerable interest, we reproduce verbatim the letter in which Mr. Parsons described his model in our contemporary, Nature, in 1896—curiously enough the year in which The Automotor Journal first saw the light, and at a time when petrol engines hardly offered the same obvious solution of the problem that they do to-day. " In the summer of 1893 I made some experiments on the effect of steam-jacketing small steam-engine cylinders by placing the whole of the cylinder and valve-chest inside the boiler. The increase of economy was so marked that I was led to try whether a small toy engine could be made to sustain its own weight in the air by the lifting power of an air-screw on the crank-shaft. " Fig. 1 shows this little engine. The boiler is ot seamless steel, i\ in. diameter, 14 in. long, and "oi in. to "015 in. in thickness; the steam cylinder, single acting, ij in. diameter by 2 in. stroke, and about "03 in. thickness of tool steel; the piston is of thin cup form, also of tool steel; the admission-valve is cylindrical, T6ff in. diameter, cutting off at f stroke. The whole of the valve and cylinder are within the boiler. Some parts of the engine were soft soldered and some hard soldered ; the screw is of cane covered with silk. The working pressure was limited to about 50 lbs. per sq. in. The total weight of the apparatus, with water, as in Fig. I, is \\ lbs. " Steam was raised by placing the boiler over a spirit-lamp, and when 50 lb. was registered on the gauge, and the engine started, it raised itself in the air vertically to a height of several yards. The revolutions of the engine were about 1,200 per min. and the i.h.p. \ horse-power. "The same engine was then mounted on a framework of cane, covered with silk, forming two wings of II ft. span, and a tail, the total area being about 22 sq. ft. The total weight was now j,\ lb., and, when launched gently from the hand in an inclined horizontal direction, it took a circular course, rising to a maximum height of about 20 ft. When the steam was exhausted it came down, having traversed a distance of about 100 yds. 88 Fig. 2.—Same engine and boiler as before, attached to twoinclined wing planes, and tail. From tip to tip of wings 11 ft. ; total surface of wings and tail about 22 sq. ft. ;total weight of whole apparatus 3| lbs. Steam raised to 50 lbs. per sq. in. and started. Length of flight about100 yards on level ; maximum height during flight about 20 ft. The propelling screw is seen in front and abovethe frame. " Fig. 2 shows the machine in mid-air. The photographs were taken by Mr. Gerald Stoney. " Considering the primitive construction of the apparatus, the result clearly showed that flights of considerable distance, possibly some miles, were quite possible with small economical steam engines mounted on aeroplanes. " The boiler was also found to be able to Steam the engine con- tinuously by using methylated spirits instead of water in the boiler, and burning the exhaust as fuel ; but when in flight, the force of the wind extinguished the flame. " It was clearly seen by the experiment that for practical com- mercial success of this class of steam apparatus an air condenser is essential, as the weight of water used in a few minutes' run equals the total weight of engine and boiler. " Without a condenser, the length of flight must necessarily be limited to a very few miles, and it would seem that the chief problem that workers in this field have to solve, is to obtain an efficient and light dry-air condenser."
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