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Aviation History
1917
1917 - 0130.PDF
FEBRUARY 8, 1917. [As a number of letters reach us signed with initials only, lome of which do not give a complete address, we would point out that such communications cannot be dealt with in our columns. Full name and address, which will not be pub- lished, must always be given.—ED] Lt. G. M. (R.F.C.). It is quite a common fallacy to suppose thai; the funda- mental reason why a dihedral angle makes for lateral stability is that the lift of a wing is greatest when the wing is hori- zontal, and nil when the wing is vertical, and that, therefore, •when a machine is tilted over on one side the wing on the lower side lifts more than the wing that is momentarily Canted upwards. This is not the case. The reaction on the wings is always at right angles to the chord, and provided tie speed remains constant a vertical wing will receive as much pressure as a horizontal one. Even when the wing is •pside down it will receive the same pressure as before, but the " lift " will act downwards instead of upwards. The accompanying diagrams should help to show why a dihedral will not in itself tend to restore the machine to an even keel until other movements than the roll occur. A machine flying on an even keel is subject to two vertical forces—one, the weight of the machine, which always acts 1 vertically downwards ; and the ther, the lift of the wings. Which acts at right angles to the chord, i.e., vertically up- wards when the machine is on an even keel. If the machine is to maintain a horizontal flight path, the lift must of course, be equal to the weight. Now, suppose the machine to be tilted over on its side by a gust or some other cause. The weight W still acts vertically downwards, but the lift L. being at right angles to the chord, is tilted with the machine, which is as far as lateral stability is concerned, subject to two forces only, W and L. As the speed is supposed to have remained constant, L is still equal to W, but no longer acting vertically. There are obviously no forces present which tend to restore lateral balance. Other conditions do, kpwever, occur, and it is from these that the righting effect is obtained. In the first place, the vertical component /of L. being one of the sides in a right-angled triangle in which L is the hypothenuse, is obviously smaller than L I = i- cos a) a«d as L = W J is smaller than W. The machine must therefore, begin to drop. Further, the horizontal component of L is an unbalanced force, and causes the machine to side- slip. When this occurs righting couples are obviously set up which tend to bring the machine back to an even keel. We have considered the vertical and horizontal components •f L separately for the sake of clearness. Actually o-f course, the machine would move in the direction R. which is the resultant of the two.forces L and W. F. W. (Bloxwich). „ , „ Apply to the R.N.A.S. recruiting office, Brook Green, Hammersmith, W. ». H. D. S. (Erdington). As they are only being tested, there is no need to keep them going for more than a few minutes. Prop. (London). For the theory and design of propellers you cannot do better than study Riach's " Air Screws," which can be had for 105. nd. post free from "FLIGHT " offices, 44, St. Martin s Lane, London, W.C. <* Monoplane " (Harrogate). , '" Beaumont " used a Bleriot monoplane in the circuit of Britain in July 1911. while Vedrines. who was second, flew a Morane-Borel monoplane. The Blackburn monoplane, with 60 h.p. Isaacson engine, was piloted by Mr. B. C. Hucks. A. J. R. (Burnley). You would find " The Aeroplane Speaks " would be very useful to you, as there is a chapter on rigging, as well as a good deal of information on the care and maintenance of a machine. The book can be had for 6s. post free from " FLIGHT " offices, 44, St. Martin's Lane, London, W.C. R. P. A. (Bristol). The 70 h.p. Renault engine had eight cylinders, with a bore and stroke fo 3 • 78 ins. and 5 • 52 ins. respectively. Nor- mally it ran at a speed of 1,800 r.p.m., and as the propeller was mounted on the camshaft, the propeller speed was 900 r.p.m. The engine was nominally rated at 70 h.p., but the actual brake horse-power was, we believe, 78 h.p. The fuel consumption was 0*64 lb. per b.h.p. hour. The first B.E biplane was, we believe, built in 1911. L. J. P. (Sleaford). You can probably obtain a copy of the Technical Terms report from the Aeronautical Society, .11., Adam Street, Adelphi, W.C. S. O. L. (Stamford). It is doubtful whether you could get a commission as a pilot in either flying service. Short sight would not neces- sarily rob you of any likelihood of success as a private pilot. You might be eligible for a commission as an Equipment Officer. Officers in the R.N.A.S. who are not pilots are given R.N.V.R. commissions. F. P. S. (Bristol). If you are passed for General Service you will probably not be able to enlist in the R.F.C. unless you are a skilled trades- man. Apply to the R.F.C. recruiting office, The Polytechnic, Regent Street, London, S.W. R. A. J. (Wellington). For particulars »f the R.F.C. Cadet Corps, apply to Adastral House, London, E.C. It is impossible to forecast what the conditions will be in June next, but if you are fit for General Service you would not be able to enlist m the R.F.C. now, as you are uaskilled. J. A. F. (Rhodes). , •See answer to .F. P. S. (Bristol). For the R.W.A.S., apply to the recruiting station. Brook Green, Hammersmith, W. F. S. (Coventry). If it can be attained without loss of power or efficiency, it would certainly be of value to get an aero engine absolutely noiseless. F. P. M. (Gosforth). See answer to F. P. S. (Bristol). There is no charge for replies in this column. S. W. H. (Manchester). There would appear to be no reason why you should not obtain a cadetship. With care you could live on your pay. Jeff. . t Your age would probably bar you. After obtaining your Commanding Officer's permission, apply to the Admiralty for the necessary form, and having filled it up send it to the Director of Air Services, Admiralty, S.W. Scoutmaster (Chertsey). There are no Flight Sub-Lieuts., R.N.V.R., but officers m the R.N.A.S. who are not pilots are given R.N.V.R. com- missions. It is possible to live on the pay, but great care will have to be exercised. R. S. A. (Shrewsbury). See latter part of reply to " JEFF." C. C. C. (Custom House). The R.F.C. recruiting office is at The Polytechnic, Regent Street, W., where you could obtain particulars as to any vacancies. A- L. M. (Coulsdon). You can obtain full particulars of the R.F.C. Cadet Corps from the Directorate of Military Aeronautic*, Adastral House. E.C. 130
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