27 



O Mark 13 Torpedo, Ref.(39 



Power Law 

 log(U„/u) ^ h - 1 



q 



■) 





> 

 / / 



log(u./U 



e) ' V ^ - 1 











/ 









o- / 





/ 



/ 

 / 



/ 







/ 



/ 

 / 



V 







>^o 





0.2 0.4 0.6 0.8 1.0 



h - I 



Figure 7 - Variation of Axisymmetric Shape Parameter A in Wake 



Then 



and 



Finally 



1 — 



n. 



In 



n 



(^)'^ 



(A„ +2) 9 + 3 



© 



1 + g 



[93] 



[94] 



[95] 



This completes the relationships required for calculating the drag from the boundary-layer 

 development. It is seen that both the momentum area and the shape parameter at the tail are 

 required for a precise solution of the drag. 



The choice of a value for q is not critical since a large difference in q results in only 

 a small error in the drag. Considering only a very limited amount of two-dimensional data, 

 Young^ uses a linear relation for Equation [92], that is, a value of q of unity. As shown in 

 Figure 7, test data for a body of revolution, the Mark 13 Torpedo,^^ though meager, indicate 



