A New Data Base of Supercooled Cloud Variables for Altitudes up to 10, 000 Feet AGL (Above Ground Level) and the Implications for Low Altitude Aircraft Icing
Final rept. Jan 1979-Jun 1982
NAVAL RESEARCH LAB WASHINGTON DC
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About 7000 nautical miles nmi of airborne measurements in a variety of supercooled cloud types and weather conditions up to 10,000 feet 3 kilometers above ground level AGL have been computerized to form a new Data Base of cloud variables applicable to low altitude aircraft icing studies. Half of the data is from the aircraft icing research flights conducted by the National Advisory Committee for Aeronautics NACA in 1946-50. The other half is from recent wintertime research flights by the Naval Research Laboratory and other organizations, mostly over the conterminous United States CONUS and nearby offshore areas. The Data Base includes liquid water content LWC, cloud droplet median volume diameter MVD, true outside air temperature OAT, horizontal extent and altitude of uniform cloud intervals as well as information on cloud type, weather conditions, data and geographic location, and other data. A variety of analyses are illustrated which yield these principal conclusions The NACA and modern CONUS measurements generally agree in most aspects for similar amounts of data in similar cloud and weather conditions. The Intermittent Maximum and Continuous Maximum envelopes in the Federal Aviation Regulations, Part 25 FAR-25, Appendix C, do not correctly describe the icing environment for altitudes up to 10,000 feet AGL. The average ice accretion rate appears to be independent of altitude between 2000 and 10,000 feet AGL.