138 SOME AERONAUTICAL EXPERIMENTS. 



instead of 5 would be exposed. As a full half horsepower could 

 be saved by this change, we arranged to try at least the horizontal 

 ponition. Then the method of control used l)y Lilienthal, which con- 

 sisted in shifting the body, did not seem cjuite as ({uick or effective as 

 the case reqnired; so, after long study, we contrived a system consist- 

 ing of two large surfaces on the Chanute double-deck plan, and a 

 smaller surface placed a short distance in front of the main surfaces in 

 such a position that the action of the wind upon it would counter- 

 balance the effect of the travel of the center pressure on tiie main sur- 

 faces. Thus changes in the direction and velocit}^ of the wind would 

 have little disturl)ing effect, and the operator would be required to 

 attend only to the steering of the machine, which was to be atfected 

 ])y curving the forward surface up or down. The lateral equilibrium 

 and the steering to right or left was to l^e attained by a peculiar torsion 

 of the main surfaces, which was equivalent to presenting one end of the 

 wings at a greater angle than the other. In the main frame a few 

 changes were also made in the details of construction and trussing 

 employed by Mr. Chanute. The most impoi-tant of these were 

 (1) the moving of the forward main crosspiece of the frame to the 

 extreme front edge; (2) the encasing in the cloth of ail crosspicces and 

 ribs of the surfaces; (3) a rearrangement of the wii'es used in trussing 

 the two surfaces together, which rendered it possible to tighten all the 

 wires l)y simply shortening two of them. 



With these plans we proceeded in the summer of 190* » to Kitty 

 Hawk, N. C. , a little settlement located on the strip of land that 

 separates Albemarle Sound from tlie Atlantic Ocean. Owing to the 

 impossi))ility of obtaining suitable material for a '2(H) s(juare foot 

 machine, we were compelled to make it only lOf) scpiare feet in area, 

 which according to the Lilienthal tabl(\s would be su]i])orted at an 

 angle of ?> in a wind of a])out 21 miles ])er hour. On the very day 

 tliat the machine was completed the wiiul bh^w from 2;") to oO miles per 

 hour, and we took it out for trial as a kite. We found that, while it 

 was su])ported with a man on it in a wind of about 25 miles, its angle 

 was much neanM' 20 than 3 '. Even in gusts of oi) miles the angle of 

 incidence did not get as low as 8 . although the wintl at this speed has 

 more than twic(* the lifting ])ower of a 21 -mile wind. As winds of ?>(> 

 miles pel' hour are Jiot plentiful on cleai' days, it was at once evident 

 that our plan of ])racticing by the hour, day after day. would have to 

 be postponed. Our system of twisting the surfaces to regulate the 

 lateral balance was tried and found to be much more elective than 

 shifting th(^ operatoi's body. On subseciuent days, when the wind was 

 too light to su])|)()rt the machine with a man on it, wo tested it as a 

 kite, working the rudders by cords reaching to the gi'ound. The 

 results were very satisfactory; yet we were well aware that this method 

 ot" testing is never wholly convincing until the I'csults are continued 

 1)V actual gliduig e\pei'ienc(\ 



