n 



the experimental arrangement could introduce a constant source of error in the 

 measurement of the cable angles. A small inconsistency in the geometry was 

 discovered in reviewing the arrangement of the experiment. Although this er- 

 ror vjas corrected the possibility of a small systematic error in the measure- 

 ment of the cable directions cannot be entirely disregarded. 



TABLE 3 - Average Values of C 



Cable 



Diameter in 

 inches 



Cr 



A 



1/1 6 



1.82 



B 



1/1 6 



1.57 



C 



1/1 6 



1.^7 



D 



1/1 6 



1.71 



E 



1/8 



1.31+ 



F 



1/8 



1.21 



G 



1/8 



1.23 



H 



1/4 



1.33 



The values of 6 tabulated in Table 2 are also subject to some uncer- 

 tainty because it could not be determined that any attempt had been made to 

 correct the measurements of the drag forces acting on the cable for end and 

 surface effects. Hovrever, inaccuracies in 6 affect only the C^ coefficient. 



DISCUSSION 



The plots of .^g , against (Figure 3) show that the theory— that 

 this value will not vary with — is reasonably well fulfilled. There is a 

 tendency for •!}gA to be larger than the average value when 4> lies between 

 1 and 2 1/2 degrees, smaller than the average value in the range between 2 1/2 

 degrees and 6 degrees and again larger than the average value in the range be- 

 tween 6 and 9 degrees. However, this deviation from the average does not sup- 

 port the postulated existence of a sin <f> term; i.e., the suggestion that C 

 may be \\rritten as C = A sin 4> + B sin^</> , where A and B are constants. This 

 may be seen by plotting .j^ , against sin . The failure of the straight line 

 fitted to such a plot to pass through the origin would indicate t?ie existence 

 of a sin (f> term in the expression for C^. Figure 5 represents a typical plot 

 of . J^ , against <f> . It is seen that a straight line through the origin fits 



