Flight Instrument for Measurement of Liquid-Water Content in Clouds at Temperatures Above and Below Freezing

A principle formerly used in an instrument for cloud detection was further investigated to provide a simple and rapid means for measuring the liquid-water content of clouds at temperatures above and below freezing. The instrument consists of a small cylindrical element so operated at high surface temperatures that the impingement of cloud droplets creates a significant drop in the surface temperature. ? The instrument is sensitive to a wide range of liquid-water content and was calibrated at one set of fixed conditions against rotating multicylinder measurements. The limited conditions of the calibration Included an air temperature of 20 F, an air velocity of 175 miles per hour, and a surface temperature in clear air of 475 F. The results obtained from experiments conducted with the instrument indicate that the principle can be used for measurements in clouds at temperatures above and below freezing. Calibrations for ranges of airspeed, air temperature, and air density will be necessary to adapt the Instrument for general flight use.