NO. 3 I.AXCLKY MEMOIB n\ MECHANICAL FLIGHT --I 



ing of tests, which mighl prevent not only serious damage hiil possibly fatal 

 accidents, that upon the assurance of the engine builder that the undertaking 

 of the small engine would in no way interfere with the completion of the large 

 one, a contract was entered into on February -'•',, 1900, which specified thai the 

 engine should be delivered by April 1, with a penalty for any delay beyond 

 that date. 



The frame for this quarter-size model was immediately begun and extra 

 workmen were employed for work on it in order that its construction should 

 in no way delay the completion of the large machine. The decision to construct 

 this quarter-size model of the large aerodrome had been made on the assump- 

 tion that, since it was to be one-sixteenth the weight of the large machine, and 

 therefore much heavier in comparison to its size than the steam models Nos. 

 5 and G, it would, therefore, not need to be so carefully constructed in order to 

 obtain sufficient strength. But when construction was actually begun it was 

 found not only that the simpler and less expensive methods which it had been 

 proposed to use in joining its frame together resulted in a weak construction, 

 but also that the time consumed in tinkering up the imperfections in the joints 

 more than counterbalanced the extra time which would have been required to 

 make the joints in the best manner from the beginning. Before going very far 

 it was therefore decide.] to make the joints by following the same process winch 

 had been developed in the construction of the previous models. The frame was 

 accordingly built in the most substantial manner, and when guyed by a system 

 of guy-wires similar to that employed for the large machine it was found to 

 be exceedingly stiff, in fact very much strouger and stiffer than the frame of 

 any of the preceding models. 



In originally planning the model the intention was to make all its linear 

 dimensions exactly one-fourth those of the large aerodrome. Before the de- 

 signs were completed, however, it was seen from the previous experience with 

 the steam-driven models that instead of the 62.5-cm. propellers, which a strict 

 adherence to the quarter-size plan would demand, it would be necessary to use 

 propellers which were at least one metre in diameter. Moreover, as the small 

 engine would be more than one-fourth the size of the engine under construc- 

 tion for the large aerodrome, a departure from the scale in the case of the 

 transverse frame would be necessary. The designs were therefore altered so 

 as to admit of using the larger propellers, and the tubes which formed the front 

 of the transverse frame were bent, as shown in the plan photograph, Plate 70, 

 in order to give a large enough space for properly mounting the engine. 



The frame with these modifications was completed in June, 1900, but no 

 engine was ready for it, as the builder bad failed to fulfill his contract for either 

 the large or the small engine, although several trips to New York had been 

 made to expedite their successful completion. 



