Yamazaki 



the bearing forces by adopting only the first term of the Birnbaum's series as 

 the chordwise distribution of the bound vortex and the regular helical surface 

 with a constant pitch as the geometrical shape of the free vortex to simplify 

 programming the numerical calculation. Accordingly I agree with Dr. Pien's 

 opinion about the procedure to calculate numerically the path of the free vortex 

 practically. I doubt the need of an exact solution for the path of the free vortex, 

 because the hydrodynamical performance characteristics obtained theoretically 

 do not agree exactly with the experimental results even in a case where the pro- 

 peller is working steadily in a uniform flow. 



86 



