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 aeroelastic codes, with Lynx flight test measurements. Simple "Baseline Models" are first established with near uniform characteristics for all codes, to enable vibration prediction improvements to be quantified as the codes are upgraded to "Current Technology" standard. The effects on vibration correlation are illustrated for various changes in analytical models including; free wakes, fuselage upwash, unsteady aerodynamics and Finite Element versus Modal methods, Some of these analytical modelling improvements are incorporated to become "Improved Technology Models" which are subsequently reevaluated with night test loads to identify rotor modelling deficiencies. On average, codes are not able to predict vibratory loads to an accuracy any greater than 50% of the Lynx measured loads.