Castagneto and Maioli 



REPLY TO DISCUSSION 



E. Castagneto and P.G. Maioli 



The authors would like to thank all those who took part in the discussion for 

 their precious contributions. 



The main aim of our paper was to present simple and practical mathemati- 

 cal relations [formula (6) and Table 5], which would permit the evaluation of 

 some dynamic characteristics of hydrofoils as applied to naval propellers in 

 ideal flow. At the same time the paper emphasized the necessity of using suit- 

 able coefficients to take the effect of viscous flow into account. 



With regard to the hydrodynamic characteristics of hydrofoils in actual 

 flow, we are very glad to learn from Dr. Kruppa's communication that some- 

 thing has already been done (at the Vosper cavitation tunnel), and is being done 

 at present (at the Berlin Technical University), to fill in the gap of which we 

 complained in our paper and which interests not only propellers but also other 

 design particulars such as rudders, stabilizers, etc. 



Dr. Morgan and Dr. Johnnson have emphasized that the design theory of 

 moderately loaded propellers operating under incipient cavitation conditions can 

 nowadays be considered as adequate, provided that NACA = 0.8 load distribution 

 and lifting-surface corrections are used. The authors take note of this with much 

 satisfaction. Undoubtedly it represents an important achievement, even if the 

 problem still remains open for other types of load distribution, and certainly it 

 justifies the further research which is being done on the dynamics of hydrofoils 

 in viscous flow, the results of which, once obtained, we hope can be presented in 

 such a plain and simple way as to be easily utilizable by all naval designers, 

 whether of propellers or not. 



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