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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 62 



The lift and drift coefificients Ky and Kx were computed from the 

 observed L and D, using such units that the coefficient is pounds force 

 per square foot area per mile hour velocity. Curves of coefficients 

 are given on figure 2, which also shows the ratio L/D, a measure of 



O ^ 9- 6 G /O /JS. /f^ /& 



Fig. 2. — Wing coefficients. 



the effectiveness of the wing. A maximum L/D ratio of i8 was 

 found for an angle of attack of 3°. For a 41-foot wing at 70 miles 

 per hour, it is believed that the lift coefficient is not greatly different, 

 but that the drift coefficient at small angles is materially reduced. 

 The effect is to increase the ratio L/D. Results of tests at the 

 National Physical Laboratory (Tech. Rept. Adv. Comm. Aero., 1912- 



