Doctors 



The effect of side walls of an endless tank on the wave resis- 

 tance of an accelerating ACV is displayed in Fig. 10. Two different 

 levels of acceleration in both deep water and finite depth were calcul. 

 ated. In all cases the wave resistance is a smooth function of the 

 tank width. For the low-speed range, increasing tank width generally 

 decreases the wave resistance. On the other hand, this trend is re- 

 versed for high speeds (greater than the hump speed). 



The case of infinite tank width is not plotted, in order to 

 avoid confusion with the case of B/a = 4 , with which it is almost 

 identical. This difference in wave resistance coefficient for the cases 

 calculated is less than 0. 01 , so that one might consider that a tank 

 width equal to four times the model beam to be essentially infinite. 



Even in finite depth there is no sudden change in resistance 

 as the model accelerates through the critical depth Froude number. 

 (A depth Froude number o f uni ty is passed when t^g/a = 14. 14 if 

 c/g = 0. 05 , and when t-y/g/a = 7. 07 if c/g = 0.1 . ) This sharply 

 contrasts the case of steady motion, in which the drop or discontinui- 

 ty in wave resistance coefficient when d/a = 0.5 and B/a =4 is 

 3. ! 



The effect of the tank end walls was found to be slightly 

 greater in finite depth, and thus only the former is shown, in Fig. 11. 

 The case of an infinitely wide tank is presented in Fig. 11a for 

 a/a, = 1,2 and °° . In the region near t = , there is a slight in- 

 crease in the resistance when a /a = 1 only. Incidentally, when 

 <r/a = 1 , part of the pressure "extends" beyond the starting end 

 wall, so one must expect some interference. When a /a = 2 , the 

 clearance from the starting end wall is half a craft length and there 

 is no noticeable interference. 



The two curves for the finite values of a were calculated 

 for a tank length L/a = 20 . There is no perceptible effect from the 

 far end wall until the model "passes" through its ima ge - as indicated 

 by one or two oscillations in the curves near tylg/a. = 20 . 



The case of B/a = 1 (that is, a two-dimensional pressure 

 band) is shown in Fig. lib. For the case of no nominal separation 

 of the craft from the starting end wall at t = , there is now a slight- 

 ly greater effect on the wave resistance. 



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