56 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 62 



The following- key will serve to identify the wings : 



Wing Swept Back 



I o degrees 



II 10 degrees 



III 20 degrees 



IV 30 degrees 



B. 



!^ 



-2» 0° 4 2" A" 6" e," 



Angle of Incidence 



lO" 12° 14' 



Fig. 18. 



16" 



Coefficients are given as pounds force per square foot per mile per 

 hour velocity. 



It appears that a sweep back of 10 degree,s and 20 degrees is of no 

 disadvantage from considerations of lift and resistance. There is, 

 however, no gain. For a sweep back of 30 degrees, the lift coeffi- 

 cient is diminished and the ratio of lift to resistance is seriously 

 reduced. What advantages there may be as regards lateral sta- 



