Project HICAT High Altitude Clear Air Turbulence Measurements and Meteorological Correlations. Volume 2

Abstract : The report describes the high altitude clear air turbulence (HICAT) measurements and meteorological correlations derived from Air Force U-2 flights with emphasis upon the results achieved since 13 March 1967, the program extension date. The program effort required the measurement of CAT velocity components at altitudes of 45,000 to 70,000 feet in 6 geographic areas. The program objective was to determine the statistical characteristics of high altitude CAT so as to improve structural design criteria. In addition, meteorological forecasts and analyses were to be correlated with the CAT measurements to improve CAT forecast procedures. In the Extended Program, 18.3 hours of high altitude CAT were located and recorded in flights covering over 156,000 miles from bases in England, Louisiana, Maine, Panama, Florida, and California. Actual vertical, lateral, and longitudinal gust velocity time histories and power spectra were determined and analyzed. Peak counts of true vertical gust velocity and derived equivalent gust velocity were obtained. A practical procedure for forecasting high altitude CAT was developed. The pilot's log, gust velocity time histories and power spectra, as well as flight tracks and meteorological descriptions of all the tests appear in Volume II of this report.