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Aviation History
1913
1913 - 0078.PDF
f/TJCHT JANUARY I8, 1913. Edited by V. E. Models for the Beginner. To the initiated in any subject, all matters connected with it appear more or less simple. To the uninitiated, the reverse is, of course, the case. Everything has to be learnt, no matter however simple. There was a time when even the most expert aeromodellist knew nothing about the flying or even the launching of the most simple model—presuming that the term simple can really be applied to any thing aeronautical. We wonder how many people, both juvenile and grown-ups, have at some time either purchased or been made a present of a model aeroplane and have failed to obtain anything in the nature of a flight out of the same ? The following article is written for the benefit of those who are interested in aviation but who have not, so far, actually indulged in any flying, model or otherwise : Before the " flying" naturally comes the " buying " of the model—unless it is a present, in which case you may have no choice. To anyone about to buy a model, I would say, don't—unless you are a member of a model club, or, have among your friends a more or less expert aeromodellist—buy a set of parts, simple as it may seem to assemble them. Unless you are something of a model engineer, your chances are more or less against success. When buying a model, never buy a cheap one, or for that matter a foreign-made one, which is, generally, the kind made for show, and not utility, nor to stand any rough usage. The machine should also be one with a single propeller, and of what is known as the loaded elevator or Canard type, i.e., elevator in front, and not with a main plane in front of the tail (elevator). On no account purchase a tractor, i.e., one which flies propeller first. If the model be a present, then the first thing to do is to find out which way it flies—propeller in front or behind—ascertaining at the same time the correct way to wind up the propeller. A case has been recently brought to my knowledge, and it is by no means an isolated one, of the possessor of a simple Bragg-Smith model spending his Christmas holidays in trying to make it fly propeller first. The type of full-sized machine with which the general public is best acquainted, is, of course, the tractor-propeller first type, and they naturally think that models fly the same way. Now when we look at any propeller we see that it has a convex and a concave side, i.e., the blade is (almost invariably) hollow faced on one side ; now it is this side that should point towards the rear in flight. A model advances forward owing to the stream of air which it drives or tends to drive backwards, and just as the hollow or curved side of an aeroplane's wing is turned downwards, so in the case of a propeller is this side turned towards the rear. Having now got our model the right way about, we have next to determine which way to wind up our rubber motor; obviously we have so to wind it up that when it unwinds it shall cause the pro peller to drive the column of air backwards. As to which way we turn it, clockwise or anti-clockwise, that all depends on the pitch of the propeller, like the thread of a screw which may be right- handed or left-handed. If the model has two (twin) propellers, then, having determined (by the method already stated) the correct way for one propeller, the other will be wound up in the opposite direction, because it will be of the opposite pitch. All this you will, of course, have found out at home, before actually setting out to fly your model. Choose a calm day for your first attempt, or, if it be perforce a more or less windy one, select a sheltered spot and test the gliding capabilities of your model; in other words, before actually flying your model, you first make a number of experiments on launching the same, first for practice, and in the second place to find out if your elevator or small plane is correctly adjusted for actual free flight. Generally speaking, the model should be launched against the wind ; there are, of course, some exceptions, but this should invariably be the case for all beginners. Theoretically the model should be launched into the air with the velocity or speed with which it flies. If launched with a velocity in excess of this it becomes at once unstable and has to " settle down " before assuming its normal line of flight. If the launching speed be insufficient, it may be unable to pick up its requisite velocity in time to prevent it falling to the ground. If your model be a monoplane of no great surface, like a Clarke's flyer, it must be launched hard, if a biplane well surfaced like the Bragg- Smith and pointed into the wind, such may be, practically speaking, held up and just released, the model being held by the motor rod in the left hand, whilst the right holds the propeller at or near the boss ; release the propeller, and then remove the left hand sharply, giving the model a slight pull forward at the instant prionto doing this. JOHNSON, M.A. To return, however, to launching for gliding test, with the motor unwound, in this case the model, no matter how well surfaced, must be projected into the air, with its nose slightly downwards. Most aeromodellists use two hands for the purpose, some grasp the motor rod or fuselage at the centre of gravity, or as near as practicable. In such a case, the machine is held high above the head with the arms outstretched. The model is then thrown forwards, and slightly downwards, the whole body swinging to the move ment like an inverted pendulum. At the moment when it is felt the model is lifting, the fingers grasping the model must be opened out, and the arm drawn swiftly forwards and downwards, or the rear part of the model will catch the hand or wrist. If it is found that the model persists in diving forwards and digging its nose into the ground, then the angle that the elevator plane makes with the horizontal must be increased slightly, not too much, until it is found that the model makes a good even glide. If the model sours up into the air, nose upwards, and then dives, the angle must be reduced. If the model be a tractor or tail-type, the adjustment is more difficult, because such models are far more sensitive to small differences than the Canard type. If the model soars up into the air and then dives, obviously there is too much lift forward, and if it refuses to rise the reverse is often the case. Such models are frequently adjusted by moving the main plane along the fuselage. The beginner should leave such models alone, for he is not so likely, until he has had some considerable experience, to obtain good results with them. Beginners would do well to confine their attention to models with single propellers and of the biplane type, such as the Bragg-Smith (simple type), which is, from its general configuration, of consider able strength, and will stand a lot of rough usage. It is possessed of exceptionally good stability, and is eminently suitable for a novice. Lubricate your rubber well, and do not overwind it. Be content with a flight of a hundred yards, and carefully note all that happens after making any particular adjustment. Remember, in the above-mentioned type of model you can steer by tilting the elevator; find out (by trial and error method) how to do this, i.e., make the model circle either to the right or left, &c, and when you have become proficient in flying such a model, then you can think of passing on to models of a less simple type. The Cambering of Piano Wire Planes. The following has been sent us by a correspondent, Mr. S. J. Stevens. We publish the same rather with the idea of inviting criticism and suggestions than because we entirely agree with the 78 rn.» The cambering of wire planes. methods advocated. The subject is one we are sure in which many aeromodellists are interested. " First make the outside shape the size and form required, carrying it across to form the central rib, as illustrated in Fig. I, then fix the other two ribs (Fig. 3); these will be found quite sufficient providing you are not constructing a wing of over 30 ins. span. If you are, carry the centre rib across and back, as illustrated in Fig. 2, having fixed the ribs you next solder a piece of finer wire beside the centre rib at the trailing edge of the plane, and carry it under the next rib and solder it to the end of the plane,
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