LIGHT AND TRIM, BUT TOUGH AS STEEL 



The strain of twenty men seated on this eggshell of an airplane body is not nearly so 

 great as the tremendous tension caused by a many-horse-powered motor driving the machine 

 through the air at twice or three times the speed of an express train. 



immediate public distribution and for 

 "The Official Pictorial History of the 

 War." 



Then comes the need for psychologists, 

 doctors, dentists, and pharmacists. Few 

 people realize that the air service must 

 have its own medical staff, first, because 

 our new flying fields are in themselves 

 large communities subject to the ordinary 

 sicknesses, and, second, because a most 

 careful check must be kept by a skilled 

 physician against the nervous wear and 

 tear of the service. Some aviators who 

 might slowly burn themselves out by too 

 steady concentration are saved by watch- 

 ful attention to the first signs of weak- 

 ness. 



LIFE OF AN AIRPLANE ENGINE ONLY 

 IOO HOURS 



Very possibly the Squadrons Sections 

 will suddenly state a need for several 

 hundred mechanical engineers to carry 

 through all the intricate oversight of 

 planes in the field. We little realize that 



the life of an airplane engine, for in- 

 stance, is hardly over a hundred hours, 

 and that the continual substitution of new 

 parts, a few at a time, often entirely re- 

 makes it. Indeed, for every plane and 

 engine which we ship to Europe we must 

 ship approximately 70 per cent of spare 

 parts for repairs. The judgment as to 

 when new parts shall be put in is the 

 answer to the life of the plane and must 

 be entrusted only to expert engineers. 



Even more difficult, on account of the 

 very much larger number involved, has 

 been the supplying of skilled mechanics — 

 men who can take an engine or a plane 

 apart and put it together again ; men 

 skilled in such work as engine-fitting, 

 welding, propeller - making, magnetos, 

 wing construction, lithography, vulcaniz- 

 ing, and the like. It has been necessary 

 to seek them out oftentimes in the by- 

 ways of industry, in small boat compa- 

 nies, for instance, where are found men 

 ideal for woodworking, or in garages 

 throughout the country, where are found 



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