This paper investigates the influence of tiltrotor blade twist on whirl-flutter stability boundaries. Preliminary evaluations indicate that the whirl-flutter speed can be increased if the blade twist slope is reduced. This positive effect results from the shift in the overall thrust toward the blade tip, increasing the flapwise bending moment at the blade root and the trim coning angle. This, in turn, generates a positive pitch-lag coupling, increasing the whirl-flutter speed. However, the shift of high sectional thrust forces toward the blade tip sections returns a higher induced drag, showing the tendency to increase the power required. The paper shows that, by using blade twist laws based on piecewise linear functions and adding the wing airfoil thickness as a second design parameter, it is possible to identify aircraft configurations that improve the whirl-flutter stability boundaries without penalizing the power required in airplane and helicopter mode flight. This is possible because the blade twist and the wing airfoil thickness have an impact on both power required and whirl-flutter speed, so a simple optimization algorithm can identify good tradeoffs. A detailed tiltrotor model representative of the Bell XV-15 is used to display the effectiveness of the proposed approach. The examples show that increases up to 21% on the whirl-flutter speed are achievable without penalties in the aircraft power required and with the additional benefit of a benign impact on rotor pitch link loads.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Exploration of the Effects of Rotor Blade Twist on Whirl-Flutter Stability Boundaries


    Contributors:

    Published in:

    Journal of Aircraft ; 61 , 2 ; 570-585


    Publication date :

    2024-03-01




    Type of media :

    Conference paper , Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English




    Optimal Tiltrotor Blade Twist to Extend Whirl-Flutter Stability Boundaries

    Muscarello, Vincenzo / Quaranta, Giuseppe | AIAA | 2023


    Optimal Tiltrotor Blade Twist to Extend Whirl-Flutter Stability Boundaries

    Muscarello, Vincenzo / Quaranta, Giuseppe | TIBKAT | 2023


    Optimization of Tiltrotor Blade Twist to Increase Whirl-Flutter Stability

    Muscarello, Vincenzo / Quaranta, Giuseppe | AIAA | 2019