Chordwise wing flexibility may passively

Contributing USMA Research Unit(s)

Center for Innovation and Engineering, Civil and Mechanical Engineering

Publication Date

Fall 9-7-2018

Publication Title

Journal of the Royal Society Interface

Document Type



Insect wings are flexible, and the dynamically deforming wing shape influences

the resulting aerodynamics and power consumption. However, the

influence of wing flexibility on the flight dynamics of insects is unknown.

Most stability studies in the literature consider rigid wings and conclude

that the hover equilibrium condition is unstable. The rigid wings possess

an unstable oscillatory mode mainly due to their pitch sensitivity to horizontal

velocity perturbations. Here, we show that a flapping wing flyer with

flexible wings exhibits stable hover equilibria. The free-flight insect flight

dynamics are simulated at the fruit fly scale in the longitudinal plane. The

chordwise wing flexibility is modelled as a linear beam. The twodimensional

Navier–Stokes equations are solved in a tight fluid–structure

integration scheme. For a range of wing flexibilities similar to live insects,

all eigenvalues of the system matrix about the hover equilibrium have negative

real parts. Flexible wings appear to stabilize the unstable mode by

passively deforming their wing shape in the presence of perturbations, generating

significantly more horizontal velocity damping and pitch rate

damping. These results suggest that insects may passively stabilize their

hover flight via wing flexibility, which can inform designs of synthetic

flapping wing robots.

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