Aeroelastic Model of Multisegmented Folding Wings: Theory and Experiment

Abstract

Morphing-wing research has garnered much attention in the aerospace community over the last decade, and the folding wing is a promising concept that can improve aircraft performance over multiple types of missions. Several high-fidelity analyses of folding-wing aeroelastic stability have been published, but most analyses are specifi ct o certain wing planforms or a fixed number of wing segments. This paper presents a general aeroelastic model that predicts the flutter speed and flutter frequency of a folding wing with simplified geometry but with an arbitrary numberof wingsegments. Thebeam-theory structuralmodelandthe strip-theoryunsteadyaerodynamic modelare coupled using Lagrange’s equations. Three experimental models are constructed, and flutter tests are performed over a wide range of fold angles. The theoretical predictions for flutter speeds are within 10% of experimentally measured values for most configurations. In general, the results show that the essential physics of the problem is captured by the present first-principles model. Furthermore, data show that increasing the fold angle causes up to 30% increase in flutter speed, which has applications in extending the flutter boundaries of morphing aircraft.