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Aviation History
1915
1915 - 0187.PDF
Flight, March 19, 1915 ^fr First Aero Weekly in the World. Founder and Editor : STANLEY SPOONER. A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport. OFFICIAL ORGAN OF THE ROYAL AERO CLUB OF THE UNITED KINGDOM. No. 325. (No. 12, Vol. VII.)] MARCH 19, 1915. Flight. Editorial Office; 44, ST. MARTIN'S LANE, LONDON, W.C. Telegrams: Truditur, Westrand, London. Telephone: Gerrard 1828. Annual Subscription Rates, Post Free. United Kingdom 151. od. Abroad CONTENTS. • 20s. od. Editorial Comment: PAGE The Vortex Theory of Sustentation 187 A Two-Seater Nieuport Biplane 189 The Aeroplane in War—Past, Present and Future 191 Aircraft Work at the Front. Official Information 2 The British Air Services 19 Royal Aero Club. Official Notices 193 From the British Flying Grounds 4 Eddies. By".rEolus" 196 The Flying Machine : The Aerofoil in the Light of Theory and Experi ment. By F. W. Lanchester, M.Inst.C.E. 198 Aircraft and the War 109 Models. Edited by V. E. Johnson, M.A. 201 With regard to photographs and descriptions of new British machines and those of our Allies, and other information which may be of help to our enemies, it should be noted that the Editor of FLIGHT, in the National interest, submits all matter of this character to the Official Press Censor before publication. Hence our readers will appreciate that many new departures in con struction or advances in detail work are necessarily held back for the present rather than the smallest risk should be run of helping those who are so strenuously fighting the Allies for the enforcement of their " Kultured" militarism.—ED. EDITORIAL COMMENT. The Vortex Theory of Sustentation. Last week we published the first instalment of Mr. Lanchester's paper entitled " The Aerofoil in the Light of Theory and Experi ment," which is continued in our present issue. Although highly technical in places and calling for a wide and extensive knowledge of hydro- dynamic theory, it is presented in such a form and with such explanatory observations, that the non-technical man can, if he diligently applies himself to the matters there dealt with, acquire a sound knowledge of the basis of the investigation upon which Mr. Lanchester is now and has for some time past been working, lne dissemination of treatises of this character, which have entailed months and years of labour in their preparation, far more than appears upon the surface, is essential tor the advancement of the science of Aeronautics; and it is by such means—the exchange of ideas, and the put> rRegUtered at the G.P.O.") l_ as a Newspaper. J TWeekly, Price 3d. L Post Tree, 8Jd. i lication of the best work and considered theories of our great scientists—that Aviation as a whole must needs progress. That there should be such men as Lanchester who are prepared to devote their all too short leisure time to the evolution of theories, which afford no imme diate or adequate return for the labour which is necessarily involved, is a matter upon which the aero nautical industry as a whole has reason to congratulate itself. Not infrequently, the essentially practical man is apt to regard the theorist as one who should be kept at arm's length—who, because he does not understand the practical difficulties which are encountered, cannot make effective use of his knowledge. On the other hand, the theorist is sometimes disposed to view the constructional side as a thing apart, between which and himself there can be no direct connection. The opinions thus enter tained may be based on actual experience—the practical man seldom approaches the theorist until he is driven into a corner—and estrangement often results because of the inability of the constructor to formulate the exact conditions governing the problem, which he wishes to have solved, in a sufficiently precise manner to enable the theorist to set to work; and the latter cannot appreciate the relative value of the facts as they arise, and is often led away on an investigation into matters of secondary importance, leaving the main problem un touched. In actual fact, theory and practice are mutually dependent upon one another, and, as we have repeatedly advocated in these columns, for their common advance ment, should be developed together. No doubt many of our readers are familiar with the vortex theory of sustentation as presented in Lanchester's " Aerial Flight"—a work that has, since its publication, become a standard textbook on the science of Aeronautics. This theory is carried a stage further in the paper to which we have already referred, and numerical examples are given in support of the soundness of the ideas upon which it is based. Briefly expressed, the Lanchester theory of sustenta tion is this—the sustentation of an aeroplane is derived from the reaction due to the production of two equal and opposite vortices in the wake of the aerofoil. The existence of this vortex pair cannot be denied, as optical demonstration, and our knowledge of the character of the air flow over the surfaces of an aerofoil, support the contention that such a motion of the air does take place ; opinions differ, however, as to the extent to which the deductions made therefrom are valid, and how far the B
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