216 ANNUAL REPORT SMITHSONIAN INSTITUTION, 195 



The accuracy of these conchisions is truly amazing when we con- 

 sider the size of their models and the short time they had to accumu- 

 late the information. We must not overlook the fact that this was 

 quite contradictory to and beyond the work of all other investigators 

 who were "better" equipped. The importance of this phase of their 

 work is best expressed in Wilbur's own words of 1908, "As soon as 

 our condition is such that constant attention to our business is not 

 required, we expect to prepare for publication the results of our 

 laboratory experiments, which alone made an early solution of the 

 flying problem possible.'' Unfortunately, this ambition was never 

 fulfilled. This phase of their work was completed in February of 

 1902. 



ADVANCED GLIDER WORK IN 1902 



Fortified with considerable flight experience and much design data 

 in which they had complete confidence, the Wrights returned to North 

 Carolina in the late summer of 1902 and constructed their third glider. 

 (See pi. 5, fig. 2, and pi. 6, fig. 1.) 



From the photograph it is apparent that this machine incorporated 

 all the refinements found necessarj'^ in the earlier models and, in addi- 

 tion, was fitted with a pair of fixed vertical fins for directional stability. 



The new wing section had a camber ratio of 1/25, with the high 

 point well forward. The total wing area was 305 square feet, the 

 front elevator had an area of 15 square feet, and the total area of the 

 vertical tail fins was 11% square feet. The wing span was 32 feet 

 1 inch with a chord of 60 inches or an equivalent monoplane aspect 

 ratio of 3.91. The gross weight without operator was 116.5 pounds. 

 The elevator was controlled by a window-sash cord over pulleys 

 (by the hand), and wing warp was operated by wires running from 

 a cradle in which the operator's hips rested. 



The lift-drag ratio of the new machine was soon established in a 

 measured glide as 8.77. Ratio of their best previous machine had 

 been slightly less than 6. The new elevator was very efficient, re- 

 quiring only 3° either side to maintain complete pitch control. By 

 flying the upper wing alone as a kite and by measuring all their glides 

 carefully, they substantiated the results of their wind-tunnel 

 experiments. 



In addition to the valuable flight experience they accumulated on 

 this machine in almost 1,000 glides during two months, they learned 

 how to overcome a rather vicious tendency to stall in the turns by re- 

 placing the fixed vertical fins with a single movable rudder controlled 

 by interconnection with wing warping. They later revealed this idea 

 in their patent No. 821393 granted May 22, 1906. 



The season's work gave them utmost confidence in their ability to 

 add an engine and continue their work in powered flight. 



