WIND-INDUCED TORQUES MEASURED ON A LARGE ANTENNA
Abstract
The fluctuating torques applied by wind forces are an important source of error in the servo systems required to aim large antennas for radar and radio astronomy. Direct measurements were made of the wind-induced torque acting about the elevation axis of a 60-ft Kennedy paraboloidal antenna. Torque was measured by a strain-gage bridge and recorded on magnetic tape. Sixty runs, each of 33 min duration, were recorded. A mean(over) squared torque spectral- density curve was obtained for each run. A two-variable function of the form used by Newton and others gives a good fit with these data. The half-power frequency values ranged from 0.029 to 0.29 radians per second, with a median value of 0.11 radian per second. A second corner frequency in the vicinity of 2. 0 radians per second was also observed. Peak torques were observed during certain runs, and equivalent aerodynamic moment coefficients were derived. Root-mean-square values of wind-torque variation were obtained for all runs.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 27, 1960
- Accession Number
- AD0250066
Entities
People
- James W. Titus
Organizations
- United States Naval Research Laboratory