Static Longitudinal Stability in a Flapping Robot

While static longitudinal stability is well understood for fixed wing aircraft, it has yet to be fully explored for flapping flight. Numerical and analytical works have suggested flapping is either inherently unstable or merely amplifies existing instabilities already present in gliding flight. Experimental work is lacking to support or refute these hypotheses. To address this, we recorded triaxial forces and moments on a 1 degree-of-freedom flapping robot mounted in the wind tunnel test section. The inertial and aerodynamic forces associated with flapping are decomposed from the complete force data to identify how each contributes to stability. Forces and moments are recorded at several different wind speeds, flapping frequencies, and with wings of varying elasticity. Static longitudinal stability is determined by evaluating the relationship between the pitching moment and angle of attack.