Forces of Oblique Winds on Telephone Wires

T N connection with studies of wire arrangements on open-wire lines 1 which Bell Telephone Laboratories have had under way for some time, it became necessary to evaluate the resistance of wires to winds. T h e method of evaluating the force of winds normal to the wires has been studied by m a n y investigators and there is a considerable a m o u n t of d a t a in the literature on this subject. T h e 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 2 (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° a n d also in t h e records of M. G u s t a v e Eiffel, 3 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 t h a t would extend these d a t a and more fully meet our requirements. T e s t s along these lines were arranged with the Guggenheim School of Aeronautics at New York University. 4 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 " M o t i o n of Telephone Wires in Wind," D.