152 SMITHSONIAN C0NTEIB1 HoXS TO KNOWLEDGE VOL. 11 



icings relative to the center of gravity of the machine was not the same as thai 

 which existed at the time of the very successful flights of 1896, as shown by Data 

 Sheet No. 1 of No. 5, May 6, 1896. When the elasticity of the tail was adjusted 

 before making this test it was thoughl thai it was made the same as in the ex- 

 periments of 1896, though accurate data as to the exact amount of this elastic- 

 ity had, unfortunately, not been kept. 



A slight change had also been made in the method employed of attaching 

 the Penaud tail to the machine. In 1896 the tail was attached to the machine 

 by means of a flat piece of wood (hickory) which had been steamed and bent to 

 the proper extent to cause the rudder to have a negative angle of about 5 de- 

 grees, hut no accurate note was made of its angle or stiffness, so that in 1899 

 no data were available as to exactly what the angle had been or how stiff the 

 spring was. Owing to the fact that wood not only warps and twists, but also 

 that any piece which has been steamed and bent gradually loses a certain amount 

 of its curvature, it was decided in 1898 to change this method of attaching the 

 tail, the wooden spring being replaced by a coiled steel spring attached to an 

 upper guy-post and connected to the tail by a bridle wire fastened to the cen- 

 ter of figure of the tail. 



After the experiment of July 7, 1899, a lower spring, consisting of small 

 rubber bands, was connected by a wire to the lower pari of the rudder aud 

 fastened to the guy-post, thereby more nearly reproducing the conditions ob- 

 tained when using a wooden spring, which, of course, tends to return the rudder 

 to its normal position when it is displaced in either direction. After attaching 

 I his lower spring to the rudder, the experiment of July U was made, and it 

 was found that the aerodrome still flew with its midrod pointed upward at a 

 very steep angle. It was, therefore, felt certain that the upper spring on the 

 rudder was too stiff, and that it should aol require so much as 1240 grammes 

 to bring it to the horizontal. This spring was, therefore, replaced by a weaker 

 one, and the angle of the rudder was also decreased until it had a negative angle 

 of only 5 degrees and required only 200 grammes placed at its center of figure 

 to bring it to the horizontal. From the description of the flight of July 19, it 

 will he seen that these changes immediately corrected the tendency of the aero- 

 drome to point its nose upward at such a sharp angle, and it will lie later seen 

 that after a further slight adjustmenl the flighl of July 2!) was made, in which 

 the proper balancing was obtained ami the aerodrome made a good horizontal 

 flight. 



After these preliminary tests with the " overhead " launching apparatus, 

 it was dismounted and the " underneath " one substituted and the experiments 

 of July 28, 2!) and August .'! were made. Everything connected with this " under- 

 neath " launching apparatus worked perfectly from the start and four flights 

 of the aerodromes were made using it. 



