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Aviation History
1927
1927 - 0289.PDF
April 28, 1927 Supplement to FLIGHT ENGINEERINGSECTION Edited by C. M. POULSEN April 28, 1927 \u Interesting Ainraft !)•-» in the Drawing Ofiirr Technical Literature CONTENTS PACE Martin I'.M.S <lisr-u>>.«'el by the Hditur 29 EDITORIAL VIEWS In the present issue of TIIK AIRCRAFT ENGINEER a de])arture has been made from our usual practice by including an aero- plane description. The circumstances are somewhat unusual, as explained in the introductory remarks, and the publication of this article must not be thought to establish a precedent, since we have no intention to devote space in this section of FLIGHT to purely descriptive articles. The P.M.3 machine with which the article deals is of con- siderable interest on account of its somewhat unusual arrange- ment and its hij:h aerodynamic efficiency (a full-scale maximum L I) of IS is claimed), and as the efficiency of air- craft must necessarily be improved if commercial utility is to be attained, it is thought that a critical examination of the design may be of interest. The whole problem of whether or not an actual machine of the size contemplated can he built for a reasonable struc- ture weight is a controversial one. and although there may be those who hold that this is ]>ossiblc. we lielieve that the majority of British designers will agree with the views expressed by the Editor that the extra economy promised hv the excellent model results may soon IR1 swallowed up if the structure should work out heavier than estimated. It may. perhajw. lie recollected that in one of the instal- ments of his Heries of articles on " Aircraft Performance." Mr. J. D. North referred to the Lympne light "planes (with '•100 cc. engines), and pointed out that the opinion expressed J\V some, that these little machines provided an example of how designers of commercial machines could made theirhow g commercial machines coul machines more efficient, was doomed to failure. At the time Mr- North pointed out that the ' -~"~ ratio of these little machines was 1 to 1-5. as cornered with (>•:? to 0-5 for the r aeroplane. The induced drag was therefore very "' large machines, to obtain the same induced drag. ave to have wing spans of 110 to l">0 ft. ^ would seem that the Martin P.M.3 is up against sou this funfl«n>pntal fact, that to act the same " span Mrt. ,.<>ver w«ghf ratio as the model, some rather the j°r''"mr.v construction woidd have to lx> employed. On thigw' < the fi£ures Pv^n n>" Mr. Martin, the value of in gfri °r the P-M-3 WO»W **• 1 • 1». "u* »«v serious change •No »W ** 1 1». "u* »«v serwe»ght would rapidly decreaw this figure. AN INTERESTING AIRCRAFT DESIGN. Martin P.M.3 discussed by THE EDITOR. This article is a somewhat unusual one for THE AIRCRAFT ENGINEER, being an examination of a design by the American aircraft designer, .lames Martin. For the benefit of readers not intimately familiar with the early history of flying in this country, it may be pointed out that James V. Martin was. for a considerable period before the war. connected with the Grahame-White Company at Hendon. where he designed a little pusher biplane of the " box-kite " type that was so popular at Hendon in those days. Mr. Martin went back to the United states, where he has been working since. Some years ago he paid a visit to this country, when he visited FLIUHT offices, bringing with him a sketch design for a tiny aeroplane in which the undercarriage was designed to fold up into the fuselage. A special feature of the design was that the pilot was intended to lie down prone in the fuselage, looking out through windows, this peculiar arrangement being chosen in order to reduce the cross-sectional area of the fuselage to a minimum. This sketch design was published in FLIUHT at the time. •James V. Martin has for years been a seeker after aero- dynamic efficiency, and was among the first to patent retract- able undercarriages. It is not. therefore, to be wondered at that this feature is incorporated in his latest design, published herewith. In fact, although the designer does not specifically state this to In1 the case, one may assume that the twin-fuselage arrangement was chosen, amons other reasons, for the greater facility with which retractable under- carriages can be incorporated in this manner. Accompanying the general arrangement drawings, wind tun- nel curves and ]>erformanee curves sent to us by Mr. James \ . Martin was a non-technical article entitled " How to Make the Commercial Aeroplane Pay." This article was. however, obviously written with the object of explaining, in non- technical language, to the business man not familiar with the technical aspects of air transport, methods whereby the aerodynamic characteristics of aeroplanes can be improved, and the effect, in dollars and cents, which such improvement has upon the dividend-earning capacity of a machine. For publication in THE AIRCRAFT ENGINEER it was not thought that this article was quite suitable, and the Editor decided to deseril>e the machine from a rather more technical point of view, quoting from Mr. Martin's article such passages as appeared relevant to the more technical treatment. In order to appreciate the nmon d'Stre of the Martin P.M.3. one should know that Mr. Martin has for many years been a believer in the bi-convex wing section, holding the view that 262a
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