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Aviation History
1912
1912 - 0155.PDF
FEBK»ARY 17, 1912. 1/liGHT <aT being the diameter), but if d is measured in &" in the above par ticular cases, the load is almost proportional to J (3d + if2), which would seem to show that the surface is also a factor in increasing the resilience. In other words, that the surface is more resilient than the inside bulk, a fact that would tend to show why (as many aero- modelists say) flat rubber is better than square." A point not referred to by Mr. Clarke is the fact that the quality of the rubber has very possibly been much improved in the last three years. Mr. Clarke, in his letter, enclosed a sample of rubber •(presumably) similar to that used by Mr. Hill—it is beautiful stuff— the finest sample of rubber we think we have ever come across. Mr. Hill's experiments, we are sure, are such as will be keenly appreciated by all aeromodelists, the one thing that Mr. Hill can do to make the debt which they owe him complete is to undertake a series of experiments which will tell us—not the amount of energy which can he put into a pound weight of rubber—but that far more interesting (and we candidly admit) difficult problem— how much can be taken out of it ? Referring to Mr. Hill's remarks on experiments in which a weight is wound up, there is nothing theoretically wrong with such experi ments. Practically, of course, at starting, the torque must be con siderably more than sufficient to lift the weight, the superfluous amount being expended in creating kinetic energy, which is ultimately expended in overwinding, causing up-and-down oscilla tions—which it was, we admit, very difficult to allow for. If you damp out such oscillations by means of friction, then the friction is difficult to allow for. Finally, in our case, as in that of Mr. Clarke's, the number of strands was large, the rubber was old (or, at any rate, not fresh), and it was unlubricated. If the reader refers to Mr. Hill's letter on " The Limit of Long- Distance Flyers Propelled by Elastic," FLIGHT, September 23rd, 1911 (and everyone interested should so refer), he will at once see, on the assumption that the rubber is capable of giving out only some 75 per cent, of the energy stored in it, i.e., 75 per cent, of -2,600 ft. lbs. per lb. weight, that we have every reason to expect in the future a very considerable increase in the distance that such models can travel, and that our present models do not possess the high degree of efficiency which some would have us Iwlieve. The gliding angle is after all the real test of efficiency—could we attain in the case of models to anything like the gliding angle exhibited by the best form of soaring birds (certainly not less than 1 in 20 or 30, a possibly I in 40 or 50) then the possible length and duration of flight would be vastly increased—provided such a result could be brought about without any practical increase in resistance such as skin friction, &c. For it is the gliding angle which is the predominating factor in the rate at which the stored up energy of the rubber is being consumed. Replies in Brief. R. HALL.—Mr. Bragg-Smith informs us with respect to the scale drawings of his model (to which you refer, and which appeared in the issue of April 15th, 1911), that the correct dimensions are, total length, 7ii ins. ; span, 57 ins. F. ROBINSON.—Your model simply did what we have noticed models of the 0-1-1-2P type always have a tendency to do ; a very nice adjustment is necessary ; it looks as if yours was not fine enough. It might be caused by a too close proximity of plane and tail, but you do not state actual distance so we cannot say. The drawing sent we conclude refers to your last model only. E. J. P. MIMALLA.—It has been shown experimentally that a well - designed propeller always sucks in air from around its periphery, and does not fling it out radially unless the pitch angle exceeds 450. Consequently, your conclusions, namely, that excep tionally good results can be obtained by affixing to the tip a short metal plate at right angles to the plate, can only be due to some peculiarity of the propeller used by you. If you care to send us one of your propellers for inspection, we shall lie pleased to rejxjrt further on the matter. When the pitch angle is less than 450 the air leaves the propeller (practically) in a cylindrical column. D. MCKAY.—Electric motors, with or without accumulators, are useless. Some people have a very vivid imagination. H. W. DUNN.—Received—but you do not state weight of rubber or length of flight. ® © ® ® THE KITE AND MODEL AEROPLANE ASSOCIATION. (27, VICTORY ROAD, WIMBLEDON.) The Paramount Body to Govern Models in this Country. OFFICIAL NOTICES. Annual General Meeting.—The annual general meeting was held on Monday, February 5th. Mr. C. R. Fairey was elected to the chair. The officers elected to serve for the ensuing twelve months were:— President—Lieut.-Col. F. C. Trollope (late Grenadier Guards) ; Vice-Presidents—-Col. J. D. Fullerton (late R.E.) F.R.G.S., F.Z.S., W. H. Dines, Esq., F.R.S. (late President R. Met. Soc), F. Hedges-Butler, Esq. Advisory Council.—Committee—Messrs. Douglas Archibald, M.A., R. M. Balston, W7. B. Brooke, H. W. Browse, T. W. K. Clarke, A.M.I.C.E , S. F. Cody, C. R. Fairey, B. M. Gillman, T. O'B. Hubbard, H. E. Hughes, V. E. Johnson, M.A., J. H. Ledeboer, M.A., F. T. Pringuer, George Roach, •George Rowlands, G. P. Bragg-Smith, E. W. Twining, B. S. Varnals, C. Fleming-Williams, W. H. Akehurst Hon. Sec). The report and balance-sheet for the year was passed as read on the proposition of Mr. Bragg-Smith seconded by Mr. E. W. Twining. It was proposed that in future that the Official Notices printed weekly in FLIGHT and monthly in Aeronautics and in the Aviation Fixture Column of the Morning Post be sufficient notice to members, and that the hon. sec. shall only send to members notices of special -events. The Chairman putting it to the meeting it was carried unanimously. A hearty vote of thanks to Major B. Baden-Powell was proposed and carried unanimously for his continued and personal interest that he had taken in the Association during his three years as President. ® ® PROGRESS OF FLIGHT A discussion which followed the general business upon the suggestions for com]>etitions for the year, made by members, will be a great help to the rule Committee. A vote of thanks to the Founder and Hon. Sec, W. II. Akehurst, was carried unanimously. Testimonial to Major Baden-Powell.—It was decided that a testimonial should be given to Major B. Baden-Powell as a slight token of esteem and for the interest he has taken in the Association. It is hoped that members and friends will subscribe generously towards it, and subscriptions should be sent at once to the hon. secretary. The form of testimonial depends upon the amount received. The presentation will take place at The Plumes Hotel, Park Royal, when the Association officially takes over the man- lifting kite outfit that he has presented to the Association. Subscriptions.—Subscriptions are now due and should l>e forwarded without delay to the hon. secretary. Members should note that the observed flights for models will take place on W7imbledon Common to-day, February 17th, at 3 p.m. They will take place on the plain, Wimbledon side of the windmill. Ail members must have their motor rods protected when flying on public spaces. badges.—Members requiring badges of the Association can obtain same from the hon. secretary at is. 6d. each. ® ® ABOUT Wr. H. AKEHURST, Hon. Sec. THE COUNTRY. NOTE.—Addresses, temporary or permanent, follow in each case the names of the clubs, where communications of our readers can be addressed direct to the Secretary. We would ask Club Secretaries in future to see that the notes regarding their Clubs reach the Editor of FLIGHT, 44, St. Martin's Lane, London, W.C., by first post Tuesday at latest. MODEL CLUBS. Aero-Models Assoc. (Sec, MALCOLM B. ROSS (N. Branch) 15. HIGHGATE AVENUE, N.). ON Saturday last M. B. Ross and R. G. Corder paid a visit to the Palmer's Green Aero Club. There was a successful duration «vent. Corder had hard luck, but Ross managed to put up 52 sees., and carried off third prize. In future there will be flying every week end at the club's flying ground (Messrs. Viver's and Sons, Lodge Farm Dairy), East Finchley, N., at 3 p.m. Saturday, March 2nd, duration competition ; entrance fee 3d. (payable on ground) shared for prizes, first, second, and third. Aberdeen Aero Club (Sec, A. SEFTON, 387, HOLBURN STREET, ABERDEEN). ON Saturday a large number of members turned up at Kincorth flying ground, where some very creditable flights were obtained. Mr. D. Brown's model flying in usual excellent style. Mr. Scott also had some very good flights but was greatly hampered by repeated breakages of rubber. Rapid strides are being made with 155
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