210 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1950 



lard in 1897. However, it was not until Wilbur idly twisted an 

 open-ended cardboard container that he conceived the idea of a biplane 

 wing structure, cross braced as a Pratt truss in the vertical plane of 

 the two spars, and yet an assembly that could be warped easily for 

 lateral control. The thought was promptly tested in the form of a 

 5-foot kite controlled by extra strings to the ground. 



1900— THE FIRST YEAR'S WORK 



With characteristic enthusiasm, the Wrights designed, built, and 

 tested their first full-scale glider (pi. 1, fig. 1) in the summer of 1900. 

 Our design information on this machine is very meager, it being based 

 solely on the two remaining photographs and flight records. Ap- 

 parently, the Wrights sought to attain pitching control by ground 

 adjustment of a fixed front horizontal "rudder," shifting the operator's 

 weight or using ballast or both, and making the "rudder" controllable. 

 There is no information on the latter method other than mention of it 

 in their writings. 



Lateral control was attained by warping the wing tips, presumably 

 by an interconnecting wire across-ship, and somehow actuated by the 

 feet. There were no means whatever provided for directional control. 



The wing panels had a 5-foot chord and 16l^-foot span, giving a 

 total area of 165 square feet. The weight of the craft was 52 pounds. 

 The wing section had a camber ratio of 1/22, with the peak well for- 

 ward. 



The craft was tested in three diflFerent ways: (1) As a man-carry- 

 ing kite in winds over 25 miles per hour ; (2) as a simple kite controlled 

 from the ground in light winds; (3) as a glider off the hilltop. With 

 the craft used as a simple kite, the L/D ratio could be computed as 

 6.2 from the measured pull of the tow line. As a glider, the L/D meas- 

 ured 6.3. 



Although their actual glider flight time totaled scarcely over 2 min- 

 utes for some 12 flights, the summer's experiments did permit them to 

 draw some very valuable conclusions : 



1. Their method of wing warp was quite satisfactory, and proper 

 pitching control could be obtained by means of a movable horizontal 

 "rudder." 



2. Their lift was less than anticipated, which they reasoned might 

 be due to using too flat a camber, air leak in the unfinished cloth 

 wing covering, or possible error in Lilienthal's tables of lift char- 

 acteristics. 



3. Their drag measurements were much less than they had estimated. 

 There seemed no explanation for this unless the Lilienthal tables were 

 in error. 



