Innovative Rotor Blade Design Code

Abstract

The competitive advantage in helicopter world market is to develop a rotor design ‘tailored’ on specific, more demanding performances such as higher cruise speed and higher cruise altitude, but, at the same time, guaranteeing the maximum level of comfort for the crew and the passengers. To achieve this goal, it is normal practice to apply some design rules to the rotor aeromechanic behaviour but the residual hub loads transferred to the supporting pylon can still be so high that, in order to meet the desired threshold of the vibratory level, some vibration absorbers have to be installed as well. The reason for this has been up to now the poor to weak prediction capability of the vibratory rotor loads due to the incomplete knowledge in the rotor wake modelling and in the aerodynamics and structural interactions which are the sources of vibratory forces.

To overcome these difficulties AW has developed a new aeroelastic code, called GYROX II, FEM based, capable of representing any complex blade shape and hub/control system/pylon features. Details of the code, together with several results of the application of the code to twin-engine light-medium helicopters, are presented. Short- and medium-term upgrading of the code in order to become more attractive design tools in an integrated aeromechanics and flight mechanics environment is finally faced.