Force Pulse Testing of Ship Models 



c , , - CO'- a. 



coh . 



a)b. 



ojb . 



ojb. 



(11) 



Then the above system of equations can be written 



R K 



(12) 



By inverting the matrix r, we can directly obtain the matrix by 



K = R 



(13) 



and the coefficients in the two coupled equations of motion may be computed. 



TEST RESULTS 



As previously mentioned testing was done at a range of Froude numbers 

 from Fr. = to 0.35. However, due to a time limitation, only the cases for 

 Fr. = 0, 0.15, and 0.30 are presented in this progress report. The results at 

 Fr. = 0.15 and 0.30 are of course directly comparable with those obtained by 

 Gerritsma. 



The responses obtained at zero speed were particularly good. In the non- 

 dimensional frequency range \ < u> ^L/g < 6 there was very little scatter and 

 the results were similar to those obtained by Gerritsma. Wall effects were 

 significant only below oj/CTi - 10 and then only at clearly defined multiples of 

 tank width. Considerable scatter in the data did occur above 6.0 which can be 

 traced to the dynamic range limitations inherent in an analog tape recorder. 

 The principal damping and added mass terms obtained from this experiment are 

 shown in Figs. 8 and 9. 



453 



