Q 



/////////// /T/ / / / ///// 



SMALL NEGATIVE 

 LIFT 



(b) 



/////// ///%/////////// 



(c) 



INCREASING NEGATIVE 

 LIFT 



DECREASING NEGATIVE 

 LIFT 



//////////////// / / / / /y 





ZERO LIFT 



(e) 



(f) 



// ////////////////// 



SMALL POSITIVE 

 LIFT 



INCREASING POSITIVE 

 LIFT 



//////////////// / / / / 



Figure 1. Change in lift with increasing velocity. 



21 



