Doctors 



oo oo 



dw / du ( W )» 7 *{Q(w, u, t) P(w, u, -0) 



-oo 



- P(w, u,t) Q(w,u, -0)}" 



cos |(7+wc)t} cos |(7 -wc)t| 



7 +wc 



7 -wc 



oo oo 



— 2 / dw / du ( W ). 7 . )P(w, u, t) P(w, u, -0) + . . . 



7T Pg J J 



—00 



sin|(7+wc)t| sin (7-wc)t}~| 



. + Q(w,u, t) Q(w,u, -0)}' 



7 +WC 



7 -wc 



t. CO aO 



. . . + 



— = I dr I dw / du ( ). 7 . sinjy(t- t )|< 



- Pg J J J 



(51) 



-°° 



JQ(w,u, t) P(w,u, t) - P(w,u, t) Q(w,u,t)[ .cos|w(s(t) - s(r))[ + . 



. . . + )P(w,u, t) P(w,u,r ) + Q(w,u, t) Q(w,u,r)[ -sin)w(s(t) - s(r))f I- 



V. 3. Results 



The (steady-state) wave resistance of a yawed ACV is shown 

 in Fig. 13. Fig. 13a indicates the marked effect of smoothing the 

 pressure fall-off on a rectangular cushion, for a Froude number of 

 unity. This is accentuated for yaw angles in the neighborhood of 10° 

 and 85° . The peaks would seem to be caused by interference bet- 

 ween short wavelets - as short wave components are not produced by 

 a smoothed distribution. The slopes of the curves are zero at yaw 

 angles of 0° and 90° - as required by symmetry. 



The variation of wave resistance of a smoothed distribution 

 with yaw angle for a series of different Froude numbers is displayed 

 in Fig. 13b. At super-hump speeds, yawing the vehicle increases 

 the effective Froude number so that the resistance drops a little. On 

 the other hand, yawing at a sub-hump speed (for example, F = 0. 4) 

 can bring the craft onto the hump (at constant speed of advance), and 

 thereby increase the resistance. 



The wave-induced side force is shown in Fig. 14. It is non- 

 dimensionalized in the same manner as the wave resistance in Eq.(3 5j 



56 



