MODELING OF FLEXIBLE ROTOR BLADES FOR HELICOPTER FLIGHT DYNAMICS APPLICATIONS

This paper describes a methodology for the treatment of rotor blade fl exibility for helicopter flight dynamics applications. A coupled flap- lag-torsion elastic rotor model, previously used in aeroelasticity stu dies, is coupled with a blade-element-type flight dynamic simulation m odel. The methodology reduces the amount of symbolic manipulation and reduces the effort required for computer implementations. The treatmen t of selected terms of the equations of motion is presented in detail, The mathematical structure of flight dynamics equations is also discu ssed, Results are presented for the frequency response to pilot inputs of a UH-60 Blackhawk in hover and forward flight, including compariso ns with flight test data. The effects of blade flexibility are general ly modest, at least for the articulated rotor configuration used in th e illustrative examples.