EXPERIMENTS WITH THE LANGLEY AERODROME. 115 



Everything connected willi the work was e.\[)e(lite(l as iiiiirh as 

 possible Avitli the expectation of l)eing able to have the first trial 

 flight before the close of ISDO, and time and money had been spent 

 on the aerodrome, which was ready, except for its engine, when the 

 time for the delivery of this arrived. Bnt now the builder proved 

 nnable to complete his contract, and, after months of delay, it was 

 necessary to decrease the force at Avork on the machine proper and 

 its launching appliances until some assurance could be had of the 

 final success of the engine. During the spring and sunnner of 1800, 

 while these delaj^s were being experienced in procuring suitable 

 engines, former experiments on superposed wing surfaces were con- 

 tinued, time was found for overhauling the two steam-driven models 

 Avhich had been used in 1896, and the small house boat was rebuilt 

 so that further tests of these small machines might be made in order 

 to study the effect of various changes in the balancing and the 

 steering, equilibrium preserving and sustaining appliances, and the 

 months of June. July, and a portion of August were spent in actual 

 tests of these machines in free flight. 



A new launching apparatus following the general plan of the 

 former overhead one, but with the track underneath it, was built 

 for the models, and it Avas used most successfully in these experi- 

 ments, more than a dozen flights in succession Iieing made with it, 

 while in every case it worked without delay or accident. As soon 

 as these tests with the models on this underneath launching apparatus 

 were completed, that for the large machine w'as built as an exact 

 duplicate, except for the enlargement, and wdth some natural con- 

 fidence that Avhat had worked so perfectly on a small scale Avould 

 work fairly on a large one. 



It was recognized from the very beginning that it would be desir- 

 able in a large machine to use " superposed *' sustaining surfaces 

 (that is, with one wing above another) on account of their supe- 

 riority so far as the relation of strength to weight is concerned, 

 and from their independence of guy wiring; and tw^o sets of 

 superposed sustaining surfaces of different patterns were built and 

 experimented with in the early tests. These surfaces proved, on the 

 whole, inferior in lifting power, though among compensating ad- 

 vantages are the strength of a '' bridge " construction which dis- 

 penses with guy Avires coming up from below, wdiich, in fact, later 

 were the cause of disaster in the launching. 



It Avas finally decided to folloAv what experiment had shown to be 

 successful, and to construct the sustaining surfaces for the large 

 machine after the "single-tier'' plan. This proved to be no easy 

 task, since in the construction of the surfaces for the small machines 

 the main and cross ribs of the framework had l)een made solid, and, 

 after steaming, bent and dried to the proper curvature, Avhile it was 



