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Aviation History
1912
1912 - 0018.PDF
f/ycHT) JANUARY 6, 1912. Conducted by V. E. The Weight of the Model and the Length or Duration of Flight. AT an aero-model competition held at the Crystal Palace in August, 1910, at which there were no less than sixty-three competitors, in class I (1 sq. ft. surface area or under) the longest flight was 212 yards ; in class II (over 1 sq. ft. but less than 2) it was 150 yards ; in class III (over 2 sq. ft. but under 4) it was 128 yards ; in class IV (over 4 sq. ft. but under 8) only 109 feet. At another competition held at the same place in June, 1911, for duration the winner's time was 46 sees. Weight of model about 4 ozs., but another model, disqualified for being considerably under weight, accomplished a duration of 61 sees. The above results are merely taken at random, and much similar evidence could be brought forward to show that apparently a weight (and therefore size within limits also) lying between 2J to 4^ ozs. is the best. The smaller the model (within limits) the longer the flight both in distance and duration. We also know of a I -oz. model which has flown 542 yards and which has a duration of 72 sees. This is not stated in any sense as being a record for this weight of model. When we turn to heavier models as stated in a recent issue a 21-oz. model has flown 300 yards. The writer has a model, weight 22 ozs., which has flown about the same distance. As long ago as July 17th, 1909, a Clarke's flyer weighing 20 ozs., flew 400 ft. Flight velocity about 40 ft. per sec. But we believe we are correct in stating that such models have flown well over 1,000 ft. A 10-oz. model has, we believe, flown a quarter of a mile. On Aug. 12th, Gamage Challenge Cup, a 4-oz. model flew 1,681 ft. iojins. It was, however, assisted by fairly high wind. As stated in last week's issue a 2j-oz. model has flown 2,265 &• None of the results given are intended as records. The question which arises then is why is the smaller and lighter model so superior to the heavier and larger type ? Admitting that such is the case, with respect to which we shall be pleased to hear from correspondents more •especially re distance and duration records of models from 6 to 8 ozs. up to a poand or so in weight ; why is it ? Before stating our •own views on the matter we invite our readers to send us their •opinions. So far as our own personal observation went, competitors last year who turned up at meetings with large machines were, practically speaking, not in it. Was it constructional faults or faults in the design of their machines, or had they really handicapped themselves unawares ? Is there some relation which must hold, say .between dimensions and flight speed not present in their design ? Or is the action of the wind sufficient to account for such dis crepancies ; being far more powerful (in proportion) in the case of light models than heavier ones, or is it because such a speciality has been made of one type of model ? We await what our correspondents have to say on the matter with considerable interest. In giving particulars of any flight kindly state both weight of model jand size, i.e., span and length ; also wind conditions if known. The above has reference to models launched by hand rand not to JOHNSON, M.A. self-rising models. Supposing for the sake of argument that for hand launched models a 4-oz. model gave the best result—then for a self- rising one the weight would be in excess of this by at least 1 to 2 ozs. The most interesting feature of the whole case in our opinion is this—is it or is it not solely a case of proper design and skill in construction or is it something else ? Replies in Brief. N. V. BRASNETT.—Personally we always place the axes of the propellers perpendicular to the base strut and not parallel to the two sides of the isosceles triangular framework. In the latter case as you say some power is undoubtedly lost—if the angle be a very small one probably it is hardly worth considering ; in the former there is some extra friction but in the case of a good bearing this seems to be the lesser of the two evils. As to any difference of power exerted by the rubber in the two cases, in practice we should assess it as nil. The bearing should either be a double one or possess a certain length—such as is given by a piece of fine tubing when the axis is perpendicular to the base strut. H. S. MELHUISH.—The difficulty with respect to the elastic motor that you have met with in building a scale model Farman biplane owing to want of requisite length is quite a common one. The best and easiest way is to depart a little from the exact type and place your propeller in front of the main planes. The same being fitted on to a motor rod running right to the tail of the machine (if so desired). This should be attached to the frame in guides so that the whole—propeller, motor rod and rubber—can be moved backwards and forwards for adjustment purposes. In order to balance the effect of a single propeller—place it not exactly in the centre of the plane form of the machine but slightly to one side. For the motor rod— use a T shaped piece of well seasoned pitch pine or a well made paper tube, the rubber motor being of course inside it, varnish when finished. Six layers of thin tough paper should suffice. Plug the ends with wood to carry the bearings. If you desire to retain the propeller in its proper place, i.e., behind the main planes, then your best plan is to make the axis of the propeller of wire with a hook on either side, i.e., on both the front and rear side of the propeller (the bearing being on the most convenient side), and use two skeins of rubber, one running from one hook to the end of the elevator sup port and the other to the end of the tail support; you will thus have a motor the entire length of your fuselage, 2 ft. 9 ins., with the propeller approximately in the middle. Here, again, it would be better to depart from the original and employ twin propellers. Of the two systems suggested, the first is the better, if anything like good flights are desired. You have no other possible form of motor at your disposal in such a small model, 3 ft. span by 2 ft. 9 ins. length ; total weight, if lbs. The weight is very great, with a supporting area of only slightly over 3 sq. ft., you will need a velocity of 19 to 20 m.p.h., which we are afraid you will find very difficult to obtain. _ ••-» """ -'.'. - PulGMT. I I ^^ "* | 1 1 "•" •. •• • P^ lL^-"H! "^B «^£ ^/N -... M .•;.,• ..: -. " ' gjag^_ "N__ / T| wBBBm m likJ 'iifSi, & . i^H 1 ^P •B TMR. C. HEMIN'S BLIiRIOT AND HOWARD WRIGHT MODELS.—The latter is fitted with a compressed- air motor with which some good (lights have been obtained. 18
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