Rous et sky 



REPLY TO DISCUSSION 



Vjacheslav N. Treshchevsky 



Kpyloff Research Institute 

 Leningrad U.S.S.R. 



I can say that the method described in the paper has been 

 used in the design of several hydrofoils, so that considerations con- 

 cerning the construction of hydrodynamical complex in general were 

 taken into account. 



DISCUSSION 



R,euven Leopold 



U.S. Navy Naval Ship Engineering Center 



Hyattsville 3 Maryland, U.S.A. 



I have a couple of questions relating to the L over D ratio. 

 Has the author established the horsepower range in which pods of 4 

 to 5 are not over-large in relation to the gears they enclose ? Would 

 not the pod of the higher L over D which enclosed the gears more ef- 

 ficiently be preferable ? 



Secondly, the statement that the higher power 'Z '-drive led 

 to a tandem propeller requirement should also be questioned. How 

 would the author propose to avoid cavitation on the aft propeller re- 

 sulting from flow distortions and vortices of the forward propeller ? 



412 



