where 



a is motion amplitude in feet, 



F and F a^e horizontal and vertical dynamic load in pounds, 

 x y 



T Q is the measured equilibrium tension in pounds, 



U is current in feet per second, and 



u is frequency in radians per second. 



These coefficients are zero when no current exists. So, to obtain some 

 comparison between current and no-current conditions the following load 

 response ratios are used: 



( 



F 

 R,„ ■ t* (23) 



f * T 



and 



TO 



& 



ERROR ANALYSIS 



Overall resolution, or accuracy, of the data analysis was dependent 

 upon the following factors: 



1. Vertical and horizontal voltages were accurate to 

 within ± 0.05 millivolt. As a result, resolution of 

 equilibrium vertical and horizontal loads is 0.006 

 pound, and, cumulatively, tension resolution is 0.009 

 pound. 



2. Phase angles between dynamic voltage and displacement 

 were accurate to ± 10 or ± 20 degrees depending on 

 signal amplitude and paper speed on the strip chart 

 recorder. The uncertainties in the load amplitude 

 depended on this angle variance and also depended on 



28 



