Oscillating-bladed Propellers 



• = 15' 



1 



20 



10 



■2* 



1. 



Fig. 2d - Variation of incidence on the blade 

 element due to shaft inclination, xjj = 0.35 

 and i9 = 15° (supposing u^^ = u^ = 0) 



Second, the variations of the incidence due to the inclination of the shaft 

 are not constant with the radius of the section, but the oscillation of the blade is 

 necessarily the same for all the sections. This leads to a difficult problem. K 

 the amplitude of the oscillation is small (for example equal to the amplitude of 

 the incidence variation at the tip), the resultant incidence on all the sections is 

 reduced, but, due to the very important difference between the hub and tip sec- 

 tions, the incidence near the hub remains too large. On the other hand, if the 

 amplitude of the oscillation is large, a favorable effect may be expected as re- 

 gards the cavitation near the hub, but the incidence variations near the tip are 



1503 



