Preston tube in a pipe was used to compute the shear stress at the wall, 

 T . The shear stress coefficient C is given by 



2 



^ Pt-Ps\"e 



w I 



for the measured shear stress and by 



C = 



^ h< 



''!l 



for the analytical shear stress. 



Figure 5 shows a comparison of the measured and theoretical values of 

 the shear stress coefficient. Agreement is good for values of - < O-^. 

 The trough, which occurs for ^ > 0.9, is somewhat overpredicted by ^T^^ 

 theory. This discrepancy in the distribution of the shear stress co- 

 efficients indicates that the present analytical model may be inadequate 

 for the precise prediction of the shear stress on the last ten percent of 

 the body. The measured values of C and C^ are tabulated in Table 2. 



MEASURED AND COMPUTED STATIC PRESSURE 

 DISTRIBUTION 



The measured and computed static pressure coefficients for Afterbody 5 

 are compared in Figure 6 at various locations across the stern boundary 

 layer. The off-body option of the Douglas potential-flow computer code was 

 used to compute the static pressure distributions for the displacement body 

 (solid lines) and the actual body (broken lines) . As can be seen in 

 Figure 6, except at x/L = 0.704, 0.987, and 1.045, the measured static 

 pressure distributions agree better with the theoretical pressure distri- 

 butions computed from the displacement-body model than those from fhe 

 original body. At x/L = 0.704, 0.987, and 1.045, the two calculation; 

 methods agree to within one percent. The discrepancy between t):ie measured 



12 



