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Aviation History
1911
1911 - 0937.PDF
OCTOBER 28, 1911. bar at A 'and B, \ in* from each end, for the propeller bearings, and the frame is finished. Propellers may either be bought or made. I make mine by planing a piece of light wood down to ,V in. in thickness and cut from it two pieces each 4J ins. by 2 ins ; then shape them to Fig. 2. Then I cut a strip of wood 6 ins. by \ in. by i in. (Fig. 3), and after boring a hole for the propeller-shaft, I make a diagonal saw-cut at each end ij ins. deep, and secure the blades in the slots with two small screws and a touch of glue. As to the elastic, the distance between the propeller hooks and the hook on the forward end of the stick should be 30 ins., and we want twenty-four strands of elastic to each propeller. Elastic should be so put on that it is in a state of moderate tension. This question of tension, however, is a stumbling block to many, as elastic is often put on too slack, and no power is obtained. It is a good rule to stretch the elastic to twice its normal length. So for each propeller we will allow fourteen complete 15-in. loops of -fV in. elastic, making in all twenty-eight strands to each propeller. This means 12 yds. of elastic to each pro peller, A little more will do no harm. The chassis is now complete, and the problem of the planes next presents itself. Lengthy experiments have shown that a proportion of roughly 3 : 1 between main plane and elevator is a good one to observe, so a little calculation gives us a main-plane area of 203 sq. ins., or 29 ins. by 7 ins., and an elevating plane of 78 sq. ins. or 13 ins. by 6 ins. Most model-builders have their own ideas as to the manu facture of planes. Mine are made of | in. by i in. wood, joined at the corners by three-way magnahum tubes. These tubes are so arranged that in the main-plane the upright tubes point upwards. The use of these will be apparent later. My planes are slightly cambered, not more than J in. rise at the outside, and they are covered with proofed silk. Having made the planes, their relative positions are very important, as the flying capacity of the machine will depend entirely on this point. i/llGHTl The back edge of the main-plane should be 2^ ins. from the front of the cross bar, A, D, B, Fig. 1, and the distance between J, K, and L, M, Fig. 1, should be 17 ins. To raise the planes clear of the elastic it will be necessary to glue i in. blocks to the top edge of the stick to which to fasten the respective planes. These should be shaped as Fig. 4 to give a wider base of support for the plane spars. The block under the entering edge of the elevating plane should be f in. thick, so as to give a slight angle of inclination. In fact, the final adjustment of the model is made by means of this block. If on trial the model rises or falls (test with some forty or fifty turns on the propellers) this block should be thickened or thinned until the adjustment is satisfactory. A thin screw through this plane-spar will afford an easy means of attachment and adjustment. In case of any great error in proportional weight having been made, a sliding weight, £ oz. or •£ oz., along the main stick will often provide a remedy. The question of lateral stability is most interesting, and the following solution is the subject of Patent No. 26720. but this article constitutes a permit to any reader of FLIGHT to manufacture a model on this principle, for his own use. Take four pieces of £ in. by £ in. wood, each 6 ins. long, and place them like little masts in the upright tubes of the angle-pieces of the main-plane, as in Fig. 5. At the top of the one at the entering edge of the main- plane fix a piece of thin wood 2 ins. long, projecting at right angles. Then turn these upright pieces until their pro jecting bars are at angles of 300 and pointing inwards. Now cover the frames thus made, with silk or paper, as in Fig. 6, and lastly make a light plane 5 ins. by 7 ins. for a rudder or entering fin. Now fix a light cane skid as shown in the sketch and the flyer is complete. It will fly and will fly straight. It will alight without damaging itself and it automatically recovers itself from any angle. What more could you want ? ® ® ® ® SCHOOL AERO CLUB NOTES. By ROBERT P. GRIMMER, General Secretary, British Federation of School Aero Clubs. ONE of the great ends of our Federation is to inculcate some know ledge of aviation into the mind of the "man-in-the-street." The utter ignorance of the general public in all matters appertaining to aviation is really appalling, and this was never so forcibly brought home to me as during my recent model aeroplane demonstrations at Felixstowe. Below I give a series of bond fide questions which were actually put to me by obviously educated and well-bred people. (1) Does it matter which way (forward or backward) the machine flies ? (2) Do you keep one propeller and motor in reserve so that they can start when the first have stopped ? (3) Does the machine fly straight up like a balloon ? (4) What oil (!) do you use for your rubber motor ? (5) Is rubber much employed as a motive power on full-sized machines? (6) Is this (indicating the winder) your launching machine ? (7) Will this monoplane (a four-ouncer) carry a passenger ? (8) This is an airship, isn't it ? (9) Monoplanes will fly upside down, won't they? (10) Wouldn't you find a shilling steam-engine a more suitable power plant than rubber ? (11; How fast do your wings flap ? (12) Can't you really make her go against this (approximately 40 m.p.h.) wind? Incredible though it may seem, several of these questions were asked by men of engineering and scientific attainments. This being so, it would seem that a more general indulgence in the sport of model flying by our younger generation would not be without its effect on their parents and friends, more especially as it is impossible to achieve any success with a model without some knowledge of the main principles of flight. I am sorry to say that in several schools the aero clubs have been recently suppressed by the authorities, the members being given in two cases the alternatives of resignation or expulsion. The reason assigned for this drastic and illiberal action was the fear lest some of the members should ultimately take up the profession of aviation, and consequently—so it was said—meet with a certain and painful death ! Each worthy and learned headmaster stated that the responsibility resting upon him was too terrible, as he felt certain that model-making would culminate in the real thing, with the sad results mentioned above. The work of the Federation has always been severely hampered by the prejudices and conservatism of the benighted school authorities of this country. In the average English school no embargo is placed upon any reasonable means of recreation, and one may find everywhere devotees of boxing, fencing, fishing, butterfly-collection, and a score of other things, but in the great majority of schools aviation has up to the present been classed with betting and gambling as things forbidden. Prom the outset the Federation has had to contend against a considerable amount of opposition on the part of school authorities, and its work has been greatly hampered by the absurd prejudices of those whose acquaint ance with the subject is confined to Ovid's version, in the original Latin, of the flights of Dtdalus and Icarus. It is interesting to con trast this attitude with that of several Cana dian School Boards, which have actually adopted aero model making as a school handicraft. It is a fact that a single School Board in Canada recently placed with an English firm an order for accessories to construct 250 aero models of the twin- screw type. I wonder if the time will ever come when an English School Board will go and do likewise. And in the meantime, while our older gener ation is supremely indifferent, and our younger generation sternly suppressed, the foreigner is gain ing bit by bit the ex perience and data which are going to assure for him in the near future the empire of the air. Mr. Archie Allan in his light costume with which he secured first prize at Tynemouth Palace Skating Carnival. It represents a BleViot C.C. monoplane (one-sixth full size). 939
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