NO. 3 LANiil.KY MEMOIB OS MECHANICAL FLIGHT L59 



of the car, smaller hinged uprights furnished in their upper pari with a small 

 slot into which a pin projected from the bottom of the forward and rear guy- 

 posts, respectively. The guy-wires from the wings being connected to the 

 lower ends of the guy-posts the torsional strain produced by a side wind was 

 immediately transmitted from the wings through the guy-wires to the guy post, 

 whence it was transmitted to the car itself, and thus prevented from acting on 

 the metal frame of the aerodrome, as shown in Plate 39. These additional short 

 struts for taking up the torsional strain were first added to the small launch- 

 ing car in 1901, and in the succeeding tests made with the quarter-size model 

 no trouble of any kind was indicated as likely to be caused by them. As it was 

 these extra struts which were directly responsible for the accident in the launch- 

 ing of the large aerodrome October 7, 1903, at the time of its first trial, and pos- 

 sibly also for that on December 8, 1903, at the time of the second trial, special 

 attention is here called to them. 



The length of travel which could be provided for the launching car in the 

 case of the large aerodrome, as well as in that of the models was necessarily 

 very limited, owing to the fact that the track had to be constructed on the top of 

 the house of the boat. It was therefore necessary, in order that the aerodrome 

 might attain a speed sufficient for soaring before being launched, to keep the 

 weight of the launching car as small as possible, a given spring tension being 

 capable of accelerating a given mass a definite amount in a given length of 

 travel. With a heavier launching car the spring tension would have to be in- 

 creased. Moreover, since the blow which would be struck when the car was sud- 

 denly stopped at the end of the track, would depend on its mass as well as its 

 velocity, there was an additional reason for trying to keep the weight of the 

 car as small as possible. 



While it was found perfectly feasible to keep the weight of the launching 

 car for the model low enough for practical purposes, in designing the launching 

 car for the large aerodrome it was only by eliminating all flooring of \he car 

 and providing merely a box frame with necessary cross-braces, that its weight 

 was kept within what appeared reasonable limits. Even then the blow which it 

 would strike when it reached the end of the track was found by calculation to 

 be exceedingly formidable. 



Referring to the drawings of Plate 40, Figs. 1, 2 and 3, it will be seen that 

 the large launching car consisted essentially of two parallel longitudinal side 

 members 6 inches deep by 1.5 inches thick by 19 feet long, connected by three 

 main sets of cross-members: one set near the rear, at the point at which the 

 rear struts for supporting the aerodrome were mounted ; a second rather heavier 

 set about the middle of its length, at the point where the strut which carried 

 the clutch-hook was mounted; and a third near the front, at the point where the 

 front struts were mounted. Projecting from the forward end of each of the 



