Lindgren, Johns son and Dyne 



—'rT-rr?-), NSMB-noz2lel9A 

 « = 8.8° 

 f/^ =0062 

 S/l=0.15 



SSPA-duct 06 



o^D =69° 

 f/l =0075 



S/l =010 



O70 

 050 



7o 



O50 



075 



\/jsi. 



30 



iO 50 60 70 80 



Figure D2 



from the leading edge of the nozzle to the impeller, only the aft part of the noz- 

 zle is made noncylindrical. The outside of the nozzle is straight. 



Tests performed at the N.S.M.B. with tanker models equipped with non- 

 cylindrical ducted propellers have shown that with this arrangement reductions 

 in SHP can be obtained for a conventional afterbody which are of the same order 

 as found for a Hogner type stern with cylindrical nozzle. The noncylindrical 

 ducted propeller offers a definite means of minimizing propeller-induced vibra- 

 tion and cavitation problems due to the homogenizing effect of the noncylindrical 

 nozzle on the inflow velocity of the propeller. 



1306 



