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Aviation History
1913
1913 - 0807.PDF
JULY 26, 1913. [/ycm] OP FLOATS of the waves on the bottoms of the floats cracked it, and we are now seeking a varnish that is flexible and absolutely waterproof." Referring to the above interesting account, our correspondents will find all their troubles re float leakage disappear if they varnish with " Bragg-Smith " varnish ; as we know, from personal experience, it is the most flexible varnish we know of, and is perfectly water proof, and keeps both its surface and colour. With regard to the types of float used, these were first designed and advocated by the writer in the early days of model hydros. All his early models were fitted with such a type, and for light models they may prove, after all, the best. But they were given up for the following reasons : In very light models in which the depth of the layer of displaced fluid is very small, so small, in fact, that as soon as the model begins to move over the surface of the water it at once begins to skim, they are most efficient. In fact, when hydroplaning they are undoubtedly the most efficient type. But when we come to heavier models, in which the depth of the layer of dis placed fluid is more in proportion, the surface tension of the fluid being proportionately less in this case, then the same result does not follow. The model does not commence to move through the water at its skimming speed, or indeed at anything like it, as was demon strated in a very practical manner with a power driven model at the Welsh Harp latt year. Naturally until such a speed (the skimming speed) is attained, this type of float experiences far greater propor tionate resistance than an end-on float. This type of model also affords more than one knotty problem with regard to longitudinal stability. Practically speaking, how ever, such can be overcome. The longest duration ever attained by the writer with a model (tail type), fitted with such a type of float, was about 30 sees. \ The tendency was, as our correspondents have also discovered, for the model to side-slip and nose dive. When correctly designed and adjusted, good flights can, however, be obtained, under favourable conditions of the atmosphere. Mr. R. V. Tivy's Steam Plant. The 'following was received from Mr. R. V. Tivy too late for insertion in last week's issue :—" The engine (3-cylinder horizontal) weighs 5 ozs., and runs remarkably smoothly. Working with 25 to 30 lbs. steam-pressure, and using a testing-boiler, I was able to obtain 1,100 r.p.m., with two 12-in. Gamage centrale tractors clamped together ; and 1,000 r.p.m. with a 15-in. two-bladed propeller of very steep pitch (about 20 ins.). I then ran the engine at 35 lbs. pressure, and got 1,800 r.p.m. out of a rather inefficient 12-in. tractor. As I shall be using a tubular boiler which will stand 50-60 lbs. pressure, there seems to be a very fair chance of my getting successful flights before the end of the year. '' Messrs. Palmer and Co. are letting me have the plant practically at cost price, and as this will be £3 to £4, I quite agree with your remarks in FLIGHT on the costliness of small plants. The total weight of the plant is to be 16 ozs., and the estimated power yj h.p. The model to which I propose to fit the plant is a very efficient one, and originally rose from the ground and flew with 2J ozs. of rubber (total weight of model, 14 ozs.); duration of run 15 to 20 sees." @ ® MODEL AEROPLANE ASSOCIATION. Official Notices. British Model Records. R. Lucas KITE AND Hand-launched Off ground ( Distance * f Duration f Distance ' j Duration Duration \. F. Houlberg C. C. Dutton F. Houlberg Hydro, off water Single-tractor screw, ( Distance hand-launched ...(Duration Do., off ground ... Duration Competitions.—The fifth annual competitio: 590 yards. 8g sees. 296 yards. I 80 sees. 45 sees. 173 yards. 68 sees. 45 sees. for the Baden-Powell Challenge •\J. E. Louch . L. H. Slatter . F. G. Hindsley . J. E. Louch ... . J. E. Louch ... Shield for the best kite of the year, was held on July 19th, on Wimbledon Common, in a light breeze. There were 14 competitors, which included the holder, A. W. Brown, of Croydon. The judges were Major B. Baden-Powell, Messrs. R. M. Balston, F. Mayer and W. H. Akehurst, who made the following awards: 1st, A. W. Brown, with 281 marks; 2nd, H. W. Browse, with 257 marks ; 3rd, J. C. H. Warwick, with 212 marks ; 4th, G. T. White, with 209 marks. Major B. Baden-Powell, in announcing the awards, stated that Mr. Brown therefore retains the shield for the fourth year in succession and wins the gold medal of the Association. Mr. Browse won the silver medal of the Association, Mr. Warwick won the bronze medal of the Association. A vote of thanks to Major B. Baden-Powell was carried with enthusiasm. Littlehampton Meeting, Bank Holiday.— Special excursion tickets will be issued from London bridge, Victoria, and all suburban stations on the L.B._ and S.C.Ry. The price, return fare, will be 4s. Competitors should obtain special leaflets from stations, giving times of train. The hon. secretary will be pleased to receive all entries for this meeting at once, so that all arrange ments can be made for judges, &c, as he will be at Burton on that day. Burton-on-Trent Meeting.—The arrangements for cheap tickets can be had from Midland and G.N.Ry. Booking Offices. Entries closed on Wednes day, 23rd. The above information is extremely interesting, especially that relative to the steam pressure, and the r.p.m. of the propeller ; about which so far as models are concerned there appears to be, practically speaking, no information. It will be interesting to see what Mr. Tivy's tubular boiler can do in actual practice. This type of boiler was, if we remember correctly, the first kind tried by Mr. H. H. Groves, but given up by him owing to its inefficiency so far as actual propeller thrust was con cerned ; a thrust of about 9 ozs. with a plant weighing 24 ozs. being the best result obtained. Moreover, such a plant is not without its dangerous element. In the case of a flash (steel coils) boiler, none such exists, because, comparatively speaking, only a few drops of water are ever in the boiler at one time. We know, personally, of several tubular boiler bursts ; one case at any rate, in which it was pure chance alone that prevented serious results. Again, the flash boiler type of steam plant is so much more efficient, Mr. Groves having recently had a flight of over half a mile with one of his models. From the scientific side, pure and simple, it will, of course, be extremely interesting to see further tests with a tubular boiler plant. Mr. Suffield's Experiments. Referring to these Mr. Tivy says : " I am sorry that I have been quite unable to find out Mr. D. J. Suffield's address. At the time when I was introduced to Mr. Suffield, Mr. Tison gave me the account of the flights in Mr. Suffield's presence. This was two years ago. I have not seen Mr. Suffield for more than a year, and have no idea of his whereabouts." Query. A correspondent sends us the following :— (i) What section rubber and how many strands would you advise for a single screw tractor r.o.g. monoplane, with 8-in. diameter pro peller, 24-in. fuselage and 20-in. span ? (2) What duration should be obtained with the above model ? (3) What is the formula for finding the pitch of a propeller of given diameter, &c. ? The difficulty in answering such a query as the above off-hand must be obvious to any competent aeromodellist, with the slight information given and none at all with respect to any especial aim for which the machine may or may not be designed. Naturally one has to commence by making a number of assump tions which may or may not be right. Since one query relates to duration, one rather suspects this is the real reason of the query ; will therefore any reader who may have obtained good duration with the above type of model and approximately the given dimensions kindly send a reply ? With respect to query No. 3, our correspondent will find an answer in the Scientific American supplement for March 30th, 1912. We trust our correspondent likes fractional indices and is not averse to mathematics. Should he be so, how ever, he will find in the article referred to, " The Design of Model Propellers and Elastic Motors," the results arrived at pre sented in the form of a simple chart, by the use of which all mathematical work is eliminated, and the solution becomes merely a process of correctly following certain curves. Perhaps it is only fair to our correspondent to add that the practical application of the formulae, &c, referred to has not, so far as the writer is aware, been especially successful. ® ® Royal Aero Club Hydro Competition will be held at Welsh Harp, Hendon, on August 9th, at 3 o'clock. Entries close first post Saturday, August 2nd. For hydro-aeroplanes rising off water (open to the world), free to members. Entrance fee to non-members, 35. Prizes: rst, £5 5-s. (presented by the Royal Aero Club) and certificate of the association ; 2nd and third, value of prizes to be announced later. Tests : A—duration ; B—stability. Maximum marks, 100—75 for dura tion, 25 for stability. Rules :—1. Competitors must be at the judges' flag at 2.45. Any competitor not present at that time will be disqualified. 2. Models must not weigh less than \ lb. 3. Competitors will be allowed to make reasonable repairs at the discretion of the judges. 4. Competitors will not be allowed to replace any part without the permission of the judges. 5. Each competitor is entitled to three trials. 6. All competitors must launch their machines in the same direction. Non-competitors, admission to ground, 3d., payable only at gate. Official Trials.—The usual monthly trials will take place on Wimbledon Common to-day (Saturday, 26th), at 3 p.m., on the Plain, Wimbledon side of the Windmill. 27, Victory Road, Wimbledon. W. H. AKEHURST.. Hon. Sec. AFFILIATED MODEL CLUBS DIARY. 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. Leytonstone and District Aero Club (64, LEYSPRING ROAD.) JULY 27TH, hydro practice 6.30 a.m., Model Yacht Pond, Wanstead Flatts. At to a.m., model flying near Brickfields. July 30th, general meeting, 64, Leyspring Road, 8 p.m. Manchester Model Ae.C. (14, WARWICK RD. N., OLD TRAFFORD). AUGUST 2ND, r.o.g. competition for best duration average of five consecu tive flights, 1st and 2nd prizes. The club would be pleased to receive catalogues of model aeroplane accessories. Paddington and Districts (77, SWINDERBY ROAD, WEMBLEY). JULY 26TH, club competion at Sudbury, r.o.g handicap, three prizes *33
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