Application of Regression Analysis to Coupled Responses at High Angles of Attack

Abstract

Some of the responses obtained at high angles of attack with largescale, free-flight models of aircraft exhibit coupled longitudinal and lateral oscillations which are not predicted using mathematical models of the aerodynamic forces and moments based on wind-tunnel and other free-flight data. Several possible causes have been postulated but not confirmed, so stepwise regression analysis techniques have been applied, to see if additional terms In the mathematical model can be identified. The use of data from angular accelerometers has also been investigated to compare the information obtained with that from the usual linear accelerometers, angular and attitude gyros, incidence and sideslip vanes and control position transducers.