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Aviation History
1920
1920 - 0342.PDF
•A-1: MARCH 25, 1920 :.•; /• • \ THE CASE FOR THE CANTILEVER WING BY " MARCO POLO " (Concluded from page 312.) \ CONCERNING the rest of the machine, little need be said, . . since this is entirely a matter of personal opinion. For a small low price machine the writer is in favour of—let it be said in a whisper only—a three-cylinder radial two-stroke engine. This would be cheap to manufacture, and should be quite .; satisfactory. The two-stroke engine is chiefly in disfavour because of its alleged excessive fuel consumption. Now it ' appears to the writer that this only applies where a wide range of speeds is required, such as for road vehicles. The aeroplane , is essentially a constant speed machine as regards 90 per r- cent, of its flying. That is to say, one would so design theengine that at the engine speed corresponding to the cruising . - speed of the machine the fuel consumption was at its most : economical point. That the engine might be a little extra- vagant in its fuel consumption when all-out, or when throttledv down to less than cruising speed, would, it appears to the writer, be of relatively small importance. — With regard to the power required for such a small machine this is largely a matter of opinion. For the weight of 600 lbs. (the figure used in comparing the efficiency of the cantilever 520 SPE£D H.RH 70 80 FIG. 12 90 mo //o wing and R.A.F. 15), it is suggested that a maximum ot 25-h.p. with a reduced engine speed for developing 17-h.p. (corresponding to cruising speed and most economical fuel consumption), would be all that was necessary. Mr. Bairstow, in his paper read before the Royal Aeronautical Society, gave a curve of speeds for various power loadings, from which it was seen that the average speed for a loading of 24 lbs./h.p. (which would be our power loading when the engine developed 25-h.p.) is 85 m.p.h. (I have replotted this curve in Fig. 12 to read loading per h.p. which is the more usual way of judging power loading). In view of the fact that the cantilever wing has a some- what higher resistance at high speeds than the ordinary wing sections on which Mr. Bairstow's curve is based, and since moreover, for this particular machine the propeller would probably be designed for maximum efficiency at cruising speed, the speed indicated by the curve might not be quite attain- able. There is little doubt, however, that a maximum speed of between 75 m.p.h. and 80 m.p.h. would be possible. At about 2/3 throttle the cruising speed would probably be somewhere in the neighbourhood of 65 m.p.h. If we assume a petrol consumption of -8 lbs./h.p./h. (which is surely not too optimistic, even for a two-stroke, since there are engines with as low a consumption as -5 lbs,/h.p./h.) the machine would do a matter of about 38 miles to the gallon, at a speed of 65 m.p.h. With the present price of petrol, No. 24 Squadron R.A.F. IT is proposed to hold an officers' re-union dinner in London on Saturday, April 24. Full particulars of the arrangements, as well as details as to copies of the Squadron history, can be obtained from Capt. V. A. H. Robeson, c/o The Manager, The London City and Midland Bank, Ltd., Tewkesbury. Airship to Float and Submerge AT the inaugural banquet of the Society of Consulting Marine Engineers and Ship Surveyors on Tuesday, Sir Fortescue FJannery, M.P., the first president, said the aerial engineer had had to borrow from the lessons taught him by the marine engineer. The internal combustion engine, the screw propeller, and the oscillating rudder were all given by the marine engineer. The airship which could fly, which could, in fact, float, and which could submerge was, in his judgment, no impossible dream of the future. Some of them might live to see it. ...;•-- this would mean a fuel cost of about ijd. per mile, whichshould surely be low enough to appeal to a great number of pilots wishing to run their own little run-about. In viewof the fact that the two-stroke engine is—or should be- cheaper to build than a four-stroke of similar type, such amachine as that outlined could probably be built to sell at a price of £200 or thereabout. At such a figure therewould undoubtedly be quite a market, not only at home, but also, and probably more so, in the colonies where the distancesare greater and where there are few railways. One can imagine a number of ranch owners and overseers to whomsuch a low-priced handy little machine would be of the very greatest service for covering large tracts of territory. If verycarefully designed, the machine could be made as stable as desired, thus making it easy to fly, and with the cantileverwings, especially if made of metal, there should be next to no trueing up to worry about. An Alternative Design Reference has already been made to another direction in which the cantilever wing would probably be found useful : For heavily staggered biplanes having the top plane set at a larger angle of incidence than that of the bottom plane in order to provide longitudinal stability without the use of a very large tail plane. Biplane combinations of this nature were examined by Hunsaker, who found that a forward stagger of the top plane, accompanied by a slightly greater angle of incidence, gave an appreciable righting couple, the magnitude of which could be controlled to a considerable extent by the amount of stagger and decalage. In the general design for such a biplane, Fig. 13 (page 343), a stagger equal to the maximum chord has been used. The amount of stagger can be altered to almost any extent, and the one I have used is meant to form a compromise between the tandem combination, which is known to give inferior results, and the largest stagger of which the results have been measured recently (4- 30 deg.). It is anticipated that such a combination, with the top plane at an angle of about 2 deg. greater than that of the bottom plane, would give sufficient longitudinal stability, while not making the machine over-stable. Whatever aerodynamical effect is attained, the drawings indicate that the view of the pilot is excellent (for a biplane), and is not very inferior to that obtainable in a parasol monoplane. At the same time, the span (for the same total wing area) is reduced to 18 ft. so that even with- out folding the machine takes up little space. If it is desired to incorporate the wing-folding arrangement, this could be done as indicated in the illustration, by pivoting the top plane, and by fitting the two halves of the bottom plane in large spar sockets built into the fuselage and held in place by quick-release fittings. If brackets were provided on the sides of the fuselage, the matter of taking off the bottom planes and hanging them on the sides of the body would not be a very lengthy operation, although it would necessarily take longer than the swinging of the top plane or the mono- plane of the parasol, Fig. 11. As the area of the biplane has been kept approximately the same as that of the monoplane, and the body, tail and under- carriage are somewhat smaller, it may be expected that the performance of such a biplane, with a 25-h.p. engine, would be approximately as follows :—Maximum speed, 75 m.p.h. ; cruising speed, 60-65 m.p.h. ; and landing speed, 37 m.p.b. <•> <$> A Handley Page in China THE twin-engine Handley Page aeroplane supplied to China recently made its official test flight with representatives of the Chinese Government on board. The machine left Nanyuan aerodrome at 2.15 p.m. with 14 passengers and 1,200 lbs. of sand which acted as test load. The machine so loaded had a total weight of 6 tons. After climbing to 6,200 ft., three circuits of Pekin and the surrounding country were made, the machine diving three times in salute over the President's Palace. The engines and the machine behaved splendidly throughout the flight in spite of the intense cold which prevailed at 6,000 ft. Mr. K. Y. Wei and Gen. Tsing, who represented the Chinese Government on the test, occupied the front seats of the machine, and after landing were en- thusiastic over its steadiness and the feeling of security it inspired. A landing was made in failing light in an aerodrome festooned with Chinese lanterns. 342
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