Estimates of the Lateral-Directional Stability Derivatives of a Helicopter from Flight Measurements (Les Evaluations des Mesures en Vol des Derivees de Stabilite Lateratles-Directionnelles D'un Helicoptere),

Abstract : The lateral-directional stability derivatives for a medium-sized single rotor helicopter have been estimated for three different forward speeds. The analysis technique is based on a least squares quasilinearization method which employs a specially formatted parameter vector so that reliable a priori estimates can be used to assist convergence. An additional unique feature is the procedure adopted to reduce the influence of unknown atmospheric inputs on the parameter estimates by means of a conglomerate analysis of several similar runs. (Author)