INVESTIGATION OF THE EFFECTS OF GUSTS ON V/STOL CRAFT IN TRANSITION AND HOVER
Final technical rept. Apr 1967-Mar 1968
HONEYWELL INC ST PAUL MN RESEARCH DEPT
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The concern in the work reported is the development of statistical models for the gust environment in the earths boundary layer for use in determining the gust response characteristics of VSTOL aircraft. A general gust model based upon published gust data was developed, and analyses of VSTOL responses with that model were conducted to determine the gust descriptors significant to VSTOL performance. An interim gust model embodying the significant descriptors was then developed for use in VSTOL gust analyses. Suggestions for meteorological experiments to measure the significant descriptors are made. The significant gust descriptors determined from the analyses are the diagonal terms of the gust covariance tensor, gust probability distributions, mean wind probability distributions, and the dependencies of these statistics on thermal stability, surface roughness, and altitude. Less critical descriptors include the off-diagonal components in the gust covariance tensor and the space-time interplay in that tensor. The significant gusts seen by the aircraft are head-on and vertical gusts on the wings head-on and vertical gust shears across the wings head-on, side, and vertical gusts on the tail and head-on and side gusts on the fuselage. Mean airspeed and sideslip angle are important parameters in VSTOL gust responses. The wing-to-tail transport delay of the gusts in forward flight also has a significant effect. VSTOL gust responses at low airspeeds are generally small due to the low dynamic pressures, and the responses are decidedly nonlinear except at low gust amplitudes.