DYNAMICS WORKSHOP ON ROTOR VIBRATORY LOADS PREDICTION

This paper reviews the results of a Dynamics Workshop focusing on the correlation of vibratory hub load predictions, from eight advanced aer oelastic codes, with Lynx flight test measurements. Simple ''Baseline Models'' are first established with near uniform characteristics for a ll codes, to enable vibration prediction improvements to be quantified as the codes are upgraded to ''Current Technology'' standard. The eff ects on vibration correlation are illustrated for various changes in a nalytical models including; free wakes, fuselage upwash, unsteady aero dynamics and Finite Element versus Modal methods, Some of these analyt ical modelling improvements are incorporated to become ''Improved Tech nology Models'' which are subsequently reevaluated with night test loa ds to identify rotor modelling deficiencies. On average, codes are not able to predict vibratory loads to an accuracy any greater than 50% o f the Lynx measured loads.