An Unsteady Lifting-Line Model for Rotors in Forward Flight
Gregorio FRASSOLDATI, Beatrice DE RUBEIS, Giovanni BERNARDINI, Massimo GENNARETTI
Abstract. This study presents a time-marching lifting-line algorithm to predict the unsteady aerodynamics of rotors. Validation studies employing purely harmonic and damped oscillatory wing and blade motions have demonstrated the solver’s ability to accurately and stably predict unsteady loads. Augmenting the free and prescribed wake solvers recently developed, this method extends their time-marching framework to rotary wing applications in forward flight. In the present formulation, wake-induced velocities are evaluated via a free-wake model, while sectional forces are computed via Küssner-Schwarz unsteady theory. The bound circulation is derived by an unsteady Kutta-Joukowski relation. From there, both load and circulation equations are cast into state-space form. A vital modification for rotating blades is the careful definition of the reduced frequency, dealing with the accuracy of the prediction of dynamic loads and circulation.
Keywords
Unsteady Aerodynamics, Rotor Aerodynamics, Rotary Wing, Küssner-Schwarz, Free-Wake, Generalized Lifting Line Theory
Published online 7/20/2026, 6 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Gregorio FRASSOLDATI, Beatrice DE RUBEIS, Giovanni BERNARDINI, Massimo GENNARETTI, An Unsteady Lifting-Line Model for Rotors in Forward Flight, Materials Research Proceedings, Vol. 69, pp 142-147, 2026
DOI: https://doi.org/10.21741/9781644904251-25
The article was published as article 25 of the book CEAS – AIDAA Conference 2025
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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