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Aviation History
1916
1916 - 1170.PDF
'-»»» [/JJGHT DECEMBER 28, igi6» // in doubt about anything aviatic, write to " FLIGHT "about it. G. W. (Southsea). In describing a rough-and-ready method of finding the pitch of an airscrew, we referred to theoretical pitch, taking the chord angles as being equivalent to the true helix angles. In practice this is not, of course, usually so. the chord angles being generally greater than the helix angles. The accom panying diagram will illustrate our point. The lines dc, ec, fc and ac represent the helix angles, which we have called Oj, a.:, 03, «4, respectively. For the sake of clearness we have shown all the chord angles 3 degrees greater than the helix angles, although this does not necessarily represent general practice. As a matter of fact, there are, we believe, pro pellers in which, at certain points, the chord angles are actually smaller than the helix angles. The angles A^a,, AJ-OJ, A3-a3, A4-a4, are called the angles of attack, and correspond to the angle of incidence of an aeroplane wing. In our diagram all these angles of attack are 3 degrees, but they may, as we have pointed out, vary along the blade of the airscrew. Near the boss, where the blade has a small velocity, some propellers have sections resembling a stream line shape rather than an aerofoil section, the blade being here more in the nature of a supporting arm. Consequently in that case the chord angle is the same as the helix angle. Glider (Kingston). There is not at present any simple formula from which the amount of dihedral angle can be calculated. It is, we believe, general practice to calculate the position of the centre of projected side area of the whole machine, and then, if this centre lie on the same line as the centre of gravity, to give the wings a dihedral angle of about 2 degrees. If the centra of area lies below the e.g., a greater dihedral is given,. and if it lies above it, a smaller. The position of the centre of pressure of an aerofoil can most simply be, and usually is, determined by tests on a scale model in a wind tunnel. In a H H A Double Fatality. Alf inquest was held on December 22nd on 2nd Lieut. P. A. Wright and 2nd Lieut. Frank Leslie Garner, both R.F.C. When flying in a biplane recently the two officers saw a machine that had alighted in a field, and apparently decided to make a descent with a view to assisting their colleagues. Owing to a sudden stoppage of the engine the biplane nose-dived from a height of 400 ft. The engine fell on Mr. Garner, who was killed instantly. The machine burst into flames, and two agricultural labourers released Mr. Wright from the debris and recovered the body of Mr. Garner. Mr. Wright received attention at a V.A.D. hospital, and was afterwards removed to another, where he died within a few hours. Verdicts of " Accidental Deaths " were returned. Another Fatal Accident. AN inquest was also held on Dec. 22nd on Lieut. H. R. Deighton Simpson, R.F.C., who was killed on Dec. 20th. tapering wing, the centres of pressure would not, of course- lie on an axis at right angles to the flight path of the machine. This fact is sometimes made use of by designers in attempting to obtain increased lateral stability, usually by incorporating with the tapering wing a diminishing angle of incidence, counting from the root towards the tip. A. G. B. (Beckenham). 1. The action of the Pitot tube type of air speed indicator was described in our " Column " on page 750 of our issue of August 31st, 1916. Under the Defence of the Realm Regula tions we cannot reply to Questions 2 and 3. 4. Mr. Hawker has, we believe, looped the loop on one of the Schneider Cup type Sopwith seaplanes, but, generally speaking, sea planes are not suited for this evolution. J. D. R. (Temple Bar). The subjects of bird flight and insect flight were pretty exhaustively dealt with in the columns of " FLIGHT "in 1911. One article, entitled " The Vortex Principle of Flight," by T. A. Dring, commences on page 489 of the issue of June 3rd, 1911, and is continued through a considerable number of issues. In this article the movements of an insect's wings, as distinct from those of a bird, are very fully described, and some highly interesting suggestions put forward. The other article, by Dr. E. T. Hankin, M.A., D.Sc, is entitled " A Study of Bird Flight," and the first instalment of this appears on page 691 of our issue of August 12th, 1911. Both articles will, we think, prove of help to you, and certainly aroused great interest and a certain amount of discussion at the time. N. F. B. (Hamilton). . Your best course would be to enter a good* works as an apprentice. Write to some of the firms advertising in " FLIGHT " and ask if they have any vacancies. A. M. (Belfast). The articles on " Soaring," with the photograph of the Wright glider stationary in the air, appeared in " FLIGHT " of November nth and 18th, 1911. Postman (Guildford). The first aerial post in the United Kingdom was flown between Hendon and Windsor on Saturday, September 9th, Monday, September nth. and Tuesday. September 12th. 1911, the carriers being Hamel and Driver on Bleriots. and Gresswell on a Grahame- White biplane. Hubert on a Grahame-White biplane was also to have made trips, but he had. a smash in starting from Hendon on the Monday. R. E. (Edinburgh). The first passenger flight on a monoplane was made at Issy-les-Moulineaux on January 5th, 1909, when M. Welfe- ringer carried M. Robert Gastambide on " Antoinette IV " for a distance of half a kilom. H H A witness stated that Lieut. Simpson was an expert pilot, and had been on active service. Immediately before the accident he had looped the loop a dozen times, and flew upside down for some distance. Afterwards he rose as if to loop again, when apparently the right plane gave way as the machine was perpendicular. The pilot regained control of the machine, which started to vol-plane down, but from a height of 500 ft. it fell like a stone. A verdict of " Death from Misadventure " was returned. Aerial Activity on Salonica Front. WRITING from Salonica on December 14 th, Mr. G. Ward Price states that " German airmen have shown a little more activity lately upon this front, with disadvantageous con sequences to themselves. Within three days three enemy machines have been brought down at different parts of our line. One flew over Salonica and was shelled by the Fleet." 1142
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