However, in actuality the fairing side force is a function of many other variables 

 some of which include angle of attack, camber, and twist along the towline length. 

 Since the individual effects of all the variables contributing to the side force 

 are currently indeterminate by evaluation or analysis, the expression for the side 

 force stated above will only provide an average side-force coefficient for the 

 towline segment evaluated. Utilizing the coefficients so determined to predict 

 the performance of other towline segments of the same design implies that the 

 magnitudes and distributions of the fairing variables causing the side force are 

 identical. This implication may not be the case. 



To obtain an estimate of the normal drag and side-loading coefficients the 

 form of the loading functions must be known or assumed. For this purpose, 



previously determined normal and tangential loading functions for the 8-18-F 



2 1 



integrated fairing shape and the NACA 0020 shape were used. The side-loading 



function for both the 8-18-F and NACA 0020 shapes was defined as: 



fg ((j)) = sin^ (j. = 0.5 - 0.5 cos (2 <{.) (4) 



The loading functions for all of the blunt nose fairing configurations were 

 assumed to be those developed for the 8-18-F fairing. These loading functions and 

 the NACA 0020 loading functions are shown in Figure 12 and 13, respectively. The 

 mathematical expressions for the loading functions are given in Table 3. 



Normal drag coefficients were determined by a regression analysis using the 

 three-dimensional computer model program. For each towline configuration and 

 speed run, average tension and angle measured at the 3.7-m (12.3-ft) scope posi- 

 tion were used as starting conditions and the force coefficients (Cg^ and Cg) were 

 varied until an acceptable agreement of predicted-to-average measured values at 

 the 5.7-m (18.8-ft) scope position were obtained. 



Side -force coefficients were determined using an analysis technique similar 

 to that used to obtain the normal drag coefficients. To determine the average 

 value of the side-force coefficient for each full towline length, the parameters 

 measured at the 5.8-m (18.8-ft) scope position were used as the starting condi- 

 tions in conjunction with the value of C^ determined as described above, and the 

 value of Cg was varied until the depressor predicted roll angle agreed with the 

 measured value. 



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