An outdoor flapping wing micro air vehicle(FWMAV)should be able to withstand unpredictable perturbations in the flight condition.The responses of the time-averaged thrust coefficient and the propulsive efficiency with respect to a stochastic flight velocity deviation were numerically investigated.The deviation was assumed to obey the Gauss distribution with a mean value of zero and a specified standard deviation.The probability distributions of the flapping performances were quantified by the non-intrusive polynomial chaos method.It was observed that both of the time-averaged thrust coefficient and the propulsive efficiency obeyed Gauss-like but not the exact Gauss distribution.The velocity deviation had a large effect on the time-averaged thrust coefficient and a small effect on the propulsive efficiency.
