CHAPTER V 

 CONSTRUCTION OF FRAME OF LARGE AERODROME 



The general plan for the large aerodrome was never a matter of uncer- 

 tainly. At the time when the first general designs were made there had been in 

 the history of mankind only one type of machine, that of the steam-driven Lang- 

 ley models, which had proved capable of flight for any considerable distance. 

 Furthermore, the selection of this type had been the result not of sudden fancy 

 or of purely theoretical consideration, but of years of the most careful experi- 

 mentation, in the course of which nearly every conceivable style of machine had 

 been tested with some form of power. It would have been worse than folly, 

 therefore, if the one clear path had been left to seek some unknown way. 



It was fully realized from the first, however, that the increase in size alone 

 would make necessary in the design for the large aerodrome a great many mod- 

 ifications from the designs of the steam-driven models. It was not possible here, 

 as in nearly every other kind of structure, simply to magnify uniformly the 

 parts and proportions of the small machine in order to obtain a successful large 

 one. This is particularly true in the case of the aerodrome, because the rapid 

 increase of weight in the larger structure is out of all proportion to the increase 

 in strength, while it is very desirable that the more expensive machine which is 

 designed to carry a human being shall be relatively even stronger than the 

 easily replaced model. This problem of increasing size without sacrificing 

 st length and stability, it was known from the beginning, would be encountered 

 in a particularly difficult form in designing the frame of the large machine, and 

 was to be solved not by the discovery of some new and wonderfully strong ma- 

 terial, but by improvements both in the general plan and the details of the ma- 

 chine. Here, as is often the case, it was not the large changes in the design but 

 the improvements in small and sometimes seemingly unimportant details which 

 demanded the most careful consideration and, as a whole, contributed most to 

 the final result. For this reason, as well as because the large changes, when 

 pointed out, are usually easily understood, the present chapter is for the most 

 pari a description of the improvement of details. 



From the experience gained in the construction of the frames of the sev- 

 eral steam-driven models, it was decided that the frame for the large aerodrome 

 must consist essentially of two principal parts. First, a rigid backbone was re- 

 quired, extending from the point of attachment of the front wings to the point 

 of attachment of the rear wings ; and this backbone, for convenience designated 



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