596 



BELL SYSTEM TECHNICAL JOURNAL 



In the case of oblique winds it was found from an analysis of the 

 data that the normal component of the force was closely proportional 

 to cos^ a over a range of angles from 0° to 60° from normal in the case of 

 each actual velocity and each size of wire. The values of Fn/cos^ a are 

 given in the accompanying Tables I (0.104-inch wire) and II (0.165-inch 

 wire). This agrees with the results obtained by Relf and Powell. - 

 However, they used only one size of wire and one wind velocity in their 

 tests. Expressing this result in terms of the normal force gives, 



F — {K' cos- a)v, /)=con8taiit- 



This empirical expression suggested that a form of relation existed 

 similar to that for the case of normal winds (equation 5a). Studying 



1.0 

 0.9 

 0.8 

 0.7 



0.6 



Q 

 <^0.5 



a 



0.3 

 0.2 



0.1 



I 



1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 



Fig. 5 — Comparison of Bell Telephone Laboratories results for normal winds with the 

 National Physical Laboratories (British) results. 



the results with this in mind the following equation was obtained, 



Fc = pV^ cos" aUy (^\ 



This form of expression holds over the range of Reynolds number 

 ( VDjv) covered and, also, over the range of angles from 0° to 60° from 

 normal. 



Since p (air density) and v (kinematic viscosity of air) are constant 

 for a particular atmosphere this equation becomes 



(6) 



Fn = K{V COS ay D. 



