NO. 4 WIND TUNNEL EXPERIMENTS IN AERODYNAMICS 



75 



M — acting about OY, pitching- moment, positive when wing tends 



to stall. 

 A'^ — acting about OZ, yawing moment, positive when wing tends 



to turn to right away from wind. 



0.4 



as 



> 



Fig. 34. 

 (Subscripts designate angle of incidence.) 



In figure 34 we can see the changes of the forces X, Y, and Z with 

 yaw and incidence. It will be noted that Y is plotted to a scale of 

 ordinates ten times greater than X and Z. This force, although 

 negative and hence acting to resist a side slip, is so small in magni- 



