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Aviation History
1912
1912 - 1185.PDF
DECEMBER 14, 1912. MODEL CLUB DIARY AND REPORTS. CLUB reports of chief work done will be published monthly for the future. Secretaries' reports, to be included, must reach the Editor on the last Monday in each month. Hendon Model Aero Club (20, ATJDLEY ROAD, W. HENDON) ALL-ROUND trophy postponed until Boxing Day meeting, when it will be competed for to decide winner permanently. Flying as usual Rog tests Leytonstone and District Aero Club (64, LEYSPRING ROAD) DECEMBER I 4TH. Flying, at 3 p.m., opposite brickfields. December nth at 10 a.m., near Bushwood Avenues. »««»• 151a, Paddington and Districts (77> SWINDERBY ROAD, WEMBLEYI DECEMBER 28TH. Lecture on " Hydro-Aeroplanes," by V. E. Johnson M.A., at St. Andrew's Hall, Ealing Road, Wembley? Illustrated1 by lantern slides. Time to commence will be announced later. Admission, (J- reserved seats, is. Applications for tickets should be made early, as accom modation is limited. Scottish *.e.S.("ROCHELLE,"LlMESIDE AVENUE, RUTHERGLEN). DECEMBER 14TH. Hydro-aeroplane demonstration, Maxwell Park" December 21st. Monthly competition at Paisley Racecourse. December a8th No official meeting, owing to holidays. Sheffield Model Aero Club (35, PENRHYN ROAD, SHEFFIELD). No further weekly competition until after next general meeting. All members are requested to see FLIGHT, December 21st, for particulars of com- [fQGHT petition on Christinas Day for Mr. Manton'i »ilver aviation medal. Tractor biplanes. Longest flight, hand-launched. S. Eastern Model Ae.C. (i, RAILWAY APPROACH, BROCKLKY,. DECEMBER »4TH, at Kidbrooke, 3.30 p.m. to 4 p.m. December 15th, at Maokheath, 8 a.m. to 10 a.m.; Woolwich Common, 10.15 »-m. to M.JO p.m. December .9th, at Blackheath, 7.30 p.m., illuminated flying. ® ® ® ® KITE AND MODEL AEROPLANE ASSOCIATION. Ofinal Notices. British Model Record.. f Distance ... A. £. Woollard ... 477 yards. ' I Duration ... A. F. Houlberg ... 89 tee*. /Distance ... G.Rowland*... ... (39 yard*. ' I Duration ... A. F. Houlberg ... JI esc*. ... Duration ... G. P. Bragg-Smith ... ts sees. Single-tractor screw, f Distance ... H.K.Weston ... 84 yard*. hand-launched ... (Duration ... F. W. Jannaway ... aa aec*. Official Trials.—To.day, Saturday, December :4th, on the ground of the Aero Models Association (Northern Branch), Finchley, at 3 o'clock. Aero Show, Olympu.—Already several clubs have written, reserving club stands. Will any club wishing to have a stand send in at once to the hon. sec., asking that one shall be reserved for them, as the space is limited. 27, Victory Road, Wimbledon. W. H. AKEHURST, Hon. Sac. Hand-launched Off ground ... Hydro, off water ® ® ® ® CORRESPONDENCE. The name and address of the writer (not necessarily for publication) MOST in all cases accompany Utters intended for insertion, or containing queries. Correspondents communicating with regard to letters which have appeared in FLIGHT, would much facilitate ready reference by quoting the number of each letter. Eiffel's- Experiments. [1690] In several recent issues of your excellent journal I note many of your correspondents venture to dissent—in part at least— from some of the conclusions arrived at by the Eiffel Laboratory experimenters as to " negative wing pressures." While I do not feel justified in going into the matter of wing pres5ures, I believe my observations on the matter of the Eiffel tests for fuselage forms may be of some interest to your readers. To begin with, the true stream-line forms of nature, as expressed in the bodies of birds, fishes, &c., have the clearly-defined nature that in the rear portions of the forms the first part of the longitudinal lines are convex in nature, later becoming concave for the remainder of their length, and in the case of " torpille" forms, the lines of the front portion are concave at the point, changing to convex as the apex is approached. In none of the Eiffel forms do any concave lines appear ; their lines seem to be either convex or approximately straight lines. Then these wind-tunnel experiments do not seem altogether satisfactory, for they do not take into consideration the influence of the propellers. For instance, were the propeller at the rear it would have the effect of drawing away from the body the displaced air-currents, so that they would not successfully snap together around the rear portion of the form, and thus they would fail to give the " reaction impulse," which is, of course, infinitely the most important value obtaining from the use of " stream-line " forms. On the other hand, were the propeller in front, the speed of the slip-streams striking against the portions of projected area nearest the circumference would be much greater than that of those striking towards the centre. In other words the slip-streams would actually strike with greatest force just where the Eiffel pressure distribution charts show the pressures to be most negative ! And vice versa. Small fuselage models could be freely but accurately suspended, and stayed horizontally some distance above the ground by suitable guy and bracing wires from both tail and apex, and these models fitted with propellers of proportionate size, and engined with motor cycle engines of such power, and geared in such manner as to produce slip-streams of such speed as would obtain with the proposed full-sized machine ; then let the engines be started, and at the same time have an air- current from a powerful blower strike the model squarely in front at a speed equal to the designed speed of the proposed full-sized finished aeroplane. There would be a testing apparatus some distance away connected with the end of model s tail. The form would be efficient to the same degree as the previously determined propeller thrust was found expressed in the "draw-bar pull" registered by the testing apparatus just mentioned. This test being performed in the open, there could be no compression where the air- current passed around model ; for in wind-tunnel experiments there is bound to be more or less compression, according to the diameters of tunnel and model. While the test I suggest would be expensive, it would not be prohibitively so, and it would seem that such a test would be the only one at all nearly identical with the conditions in actual practice. If the wind-tunnel method must be used, by all means it should not be placed horizontally. It should be in a vertical position, and the air-current should flow downward, so that " draw-bar pull " might be accurately determined (weight of model, of course, being deducted). The perforation system would be used only in esti mating distribution of pressures. 351, Well Street, Chicago. J. B. McQuKKNY. Measuring Altitude. [1601] The following idea may be of interest to some of your readers:— It is commonly known that the barograph is the most accurate instrument for measuring the height of a flying machine, but 10 \'n\g as the machine can lie distinctly observed, a person on the ground at the time the aviator passes over him, can make a fail ly accurate measurement of his altitude with the simple instrument here described :— Take a common yard slick and make a slide of sheet tin to fit over it, as is shown in the illustra'ion. The slide should fit snugly enough so that it will remain in any position in which it is set, until a reading of the scale can be made. The slide is mat e by cutting out a slot at the centre of a strip of tin in such a way as to form two points, which, when bent at right angle with the strip, will be just one inch apart. The pattern in the upper left-hand corner of the illustration shows the way the tin strip should be cut to form these pointi. This operation is best performed with a chisel cutting upon tin dotted lines, and bending upward upon the solid lines. After forming the points accurately, bend the strip around the yard stick in the form shown in the lower right hand corner of the sketch, and fit it over the stick so that the figures upon the scale can be read through the slot in the centre. To ascertain the height of an aeroplane, its length must be known. Lying upon your back upon the ground you place the end of the stick to your eye and set the slide so that I he aeroplane Can be just Sighted lengthwise between the two points. Supposing the slide to stand at 14, multiply the length of the machine by 14, and the product will be the height in feet. For the standard Wright machine, allow 40 ft. ; for the baby Wright machine, allow 20 ft. ; for the Curtiss machine, allow 30 ft. ; and for the majority of monoplanes, 30 ft. Thus, suppose the standard Wright machine is flying al>ove you ; if, after sighting, the slide stands at 15, multiply 40 by 15, and the product, 600, will be the height in feet at which the aeroplane is flying. This system was first used by the Wright Brothers at their testing grounds near Dayton, Ohio. The device is one that will give considerable amusement and instruction to both old and young. 3, Walsingham Road, Hove. C. H. F. WIEDMAHN. 1185
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