164 



DIFFUSION RATIO II60 SELF PROPULSION. 



FIGURE 10. Vehicle A full-scale velocity 

 profiles 12.5 percent and 25 percent of 

 propeller radius from the hull . 



y 0-7 



0-6 



O* 



SO 



°/o PROPELLER RADIUS 



CONTROL 

 SURFACE 



20 lO O lO 20 



ANGULAR POSITION (*) 



40 



FIGURE 11. Vehicle B model velocity pro- 

 files at position 12.5 percent of propeller 

 radius from the hull. 



DIFFUSION RATIO. 



1-233 SELF PROPULSION 



I -175 



I I I I 



0.7 I 000 UNPOWERED 



20 10 o 10 20 



ANGULAR POSITION (°) 



FIGURE 12. Vehicle B model velocity pro- 

 files at position 33.5 percent of propeller 

 radius from the hull. 



DIFFUSION RATIO 



1233 SELF PROPULSION 



1175 



III I 



OB 1000 UNPOWERED 



O 7 . 



0-6 



0-4 . 



20 10 o 10 20 



ANGULAR POSITION (°.) 



Discussion of Measured Data 



It is clear from Figure 16 that the relative magni- 

 tude of the velocity defect at the two radii con- 

 sidered on vehicle A is virtually unaffected by the 

 propeller, and is subject to only a very small 

 scale effect. The latter gives rise to a reduction 

 in the depth of the velocity defect between the 



model and full-scale equivalent to an increase of 

 between 1 percent and 3 percent in the ratio of 

 minimum velocity in the 'trough' to the mean veloc- 

 ity at the edge of the 'trough'. It can be seen 

 from Figure 19 that for vehicle A the actual values 

 of the velocity defect are considerably lower than 

 predicted by the empirical relationship derived 

 from two-dimensional test results. This is not 



