Calculations and experimental resulte of the adaptive twist control concept of reduced helicopter vibrations and noise emissions.Proceedings: The main sources of helicopter vibration and noise emissions and adaptive concepts to reduce them.

This paper deals with the sources of helicopter vibration and noise emissions. It shows and evaluates adaptive concepts to reduce them. The main reasons for these emissions are aerodynamic effects such as blade-vortex-inter action (BVI), aerodynamic hysteresis, and local transonic effects at the forward moving blade. After a review of conventional control concepts to reduce the vibrations and/or sound emissions, the possibilities to realise an adaptive rotorblade are explained. The understanding of the interaction between the aerodynamic sources and the resulting vibrations and noise is the basis of the design of optimal control concepts.