CONSIDERATIONS IN THE DEVELOPMENT OF THE COUPLED ROTOR FUSELAGE MODEL

A collaborative programme between Westland Helicopters Limited and the Defence Research Agency has culminated in the first software release of the Coupled Rotor Fuselage Model (CRFM), The constituent modules of this new code are described and associated examples are provided to i llustrate the advantages of CRFM to enhance rotorcraft modelling. The rotor dynamics representation is based on a complex rotor mode analysi s which is designed to accommodate a wide range of hub configurations and is coupled to the fuselage dynamics to include hub motions, Algori thms for the timewise solution of modal response are reviewed and a ne w technique is described which provides a more accurate spanwise Force Integration procedure to determine rotor loads. A main feature of CRF M is to extend simulation to manoeuvring flight conditions. To achieve this, a pilot control logic is discussed to realistically fly three d imensional manoeuvres, and a new wake model is included to address the first order implications of manoeuvring flight on the wake geometry.