The only unknown factor in the system is the drag coefficient B for 

 the array. For the present array, we cannot obtain a value of B from the 

 literature. For the cylindrical array, however, we found that B = 0.16|Uq| . 

 Since the present array has the same dimensions as the cylindrical array, 

 values of 8 a few times smaller than that for the cylindrical array seem to be 

 reasonable . 



If we plot the value of | U j versus the value of U) which will give 

 a specified maximum dynamic stress for various values of L, we will have 

 curves like those shown in the following diagram . The envelope (dashed line) 

 drawn through 



lUo 



L, -- 20,000 



W 



the first minimum of each of these curves has the following significance. In- 

 put characteristics | Uq| and UU corresponding to a point which lies on or below 

 this envelope will never produce a maximum dynamic stress greater than the 

 specified one for any value of L up to 20,000 feet. Then, if the specified 

 maximum dynamic stress is the design stress for dynamic loads of a particular 

 cable, this envelope is the boundary of safe (points lying below it) and unsafe 

 (points lying above it) input characteristics . 



22 



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