Design of a Tiltrotor Semi-Span Wind Tunnel Model for Whirl Flutter Investigations

The Clean Sky 2 Advanced Testbed for TILtrotor Aeroelastics (ATTILA) project is aimed at the design, manufacturing and testing of a semi-span aeroelastic wind tunnel model of the Next Generation Civil TiltRotor (NGCTR). This paper provides a description of the ATTILA tiltrotor whirl flutter testbed design, as well as the design and test methodology and associated numerical modelling. In advance of the first wind tunnel test entry, the design activities rely on multi-level code-to-code validation as presented herein to improve confidence in the flutter predictions. The available numerical tools have been used to tailor the design to the desired flutter characteristics in the presence of the limitations associated with testing in Froude-scale conditions. Robustness of the predictions and design is investigated through parametric variations associated with modelling assumptions and design features. Finally, an outlook on the future dynamic characterization and wind tunnel test activities is provided.