GAHEL: General code for helicopter dynamics

The reduction of vibrations is a fundamental step in the development of a new helicopter. Nevertheless most of the programs used during the preliminary plan impose the general architecture of the helicopter without taking enough into account vibration criteria. It is harmful to the reliability of the rotorcraft, to the performances for military helicopters and to the crew and passengers comfort. More over the needed modifications can be difficult to achieve because of price and delays. For these reasons EUROCOPTER has decided five years ago to develop a new engineer tool called GAHEL (General Architecture of Helicopter) containing relatively simple models which enable to avoid fundamental problems by providing some general architecture parameters, and to optimize the anti-vibration devices. The ultimate aim of the tool is to make it possible to define a virtual helicopter optimized from a dynamic point of view.