NO. 4 



WIND TUXNEL EXPERIMENTS IN AERODYNAMICS 



69 



banking " moment. This " natural banking " moment is increased 

 nearly 100 per cent if the wing has a sweep back of but 10 degrees. 

 The moment for a sweep back of 20 degrees is still greater. 



Fig. 30. 



In view of the structural difficulties in making strongly swept back 

 wings, and the loss of efTectiveness as carrying surface for a sweep 

 of more than 20 degrees, one would conclude that if any sweep back 

 be used, about 10 or 15 degrees is sufficient. 



