Forces of Oblique Winds on Telephone Wires 



By J. A. CARR 



In aerial line design it is advantageous to know the effect of oblique winds 

 as well as cross winds. This paper gives the results of wind tunnel tests 

 made on 0.104-inch and 0.165-inch diameter wires for each 10° angle of 

 obliquity between 0° and 90° using wind velocities of 30 to 90 miles per hour 

 in steps of 10 miles per hour. These results are then analyzed to determine 

 (1) their compliance with the law of dynamic similarity and (2) the magni- 

 tudes of the various wind components. From these analyzed results an 

 expression is developed for the force of oblique winds in terms of the com- 

 ponent normal to the wires. 



IN connection with studies of wire arrangements on open-wire lines ^ 

 which Bell Telephone Laboratories have had under way for some 

 time, it became necessary to evaluate the resistance of wires to winds. 

 The method of evaluating the force of winds normal to the wires has 

 been studied by many investigators and there is a considerable amount 

 of data in the literature on this subject. The contrary was found to 

 be true in the case of oblique winds or those not normal to the line. 

 This latter case has been described briefly in the records of a test made 

 in the National Physical Laboratories ^ (British) on a 0.375-inch 

 diameter smooth wire at a wind velocity of 40 feet per second (27.3 

 m.p.h.) with the wire at angles to the wind ranging from 0° to 90° 

 (normal) in steps of 10° and also in the records of M. Gustave Eififel,^ 

 who made a similar test at somewhat higher velocities. Since the 

 wires we are concerned with range from about 0.1 to 0.2 of an inch in 

 diameter and the wind velocity ranges from about 30 to 90 miles per 

 hour, it appeared desirable to conduct a series of wind tunnel tests that 

 would extend these data and more fully meet our requirements. Tests 

 along these lines were arranged with the Guggenheim School of 

 Aeronautics at New York University.'* Subsequently, a series of tests 

 was made in the New York University wind tunnel on 0.104-inch and 

 0.165-inch diameter smooth copper wires for each 10° angle ranging 

 from 0° to 90° using wind velocities of 30 to 90 miles per hour in steps 



1 "Motion of Telephone Wires in Wind," D. A. Quarles, Bell System Technical 

 Journal, April 1930. 



2 Reports and Memoranda Xo. 307, January 1917, entitled "Tests on Smooth 

 and Stranded Wires Inclined to the Wind Direction," by E. F. Relf and C. H. 

 Powell. 



^"Nouvelles Recherches sur La Resistance De L'Air et L'Aviation," book by 

 M. G. Eiffel. 



* These tests were conducted by Professor Alexander Klemin and his associates. 



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