Army-Navy Precipitation-Static Project: Part IV-Investigations of Methods for Reducing Precipitation-Static Radio Interference

Investigations of methods for control of precipitation static are discussed. Because of difficulties associated with careful studies of the performance of antistatic devices on aircraft flying in natural charging conditions, methods were devised that permitted natural conditions to be simulated in fair-weather flights and in a laboratory hangar constructed especially for this purpose. Studies showed that interfering noise associated with the use of bare-wire antennas was roughly proportional to the amount of corona-current discharge. It was found that the use of antennas insulated with polyethylene provided comparatively static-free radio reception by preventing corona discharge from the antenna. Correlated ground and flight experiments showed that, unless the corona discharge occurs at areas adjacent to antennas, little noise is produced in the radio receiver. The characteristics of several types of electrostatic dischargers, intended to reduce the equilibrium potential of the airplane for a given charging condition, were examined. The dry-wick discharger recently adopted by the military services was found to give the best over-all electrical and mechanical performance.