 The calculations that purported to show that bumblebees cannot fly are based upon a simplified linear treatment of oscillating <unk> . The method assumes small amplitude oscillations without flow separation . This ignores the effect of dynamic stall ( an airflow separation inducing a large vortex above the wing ) , which briefly produces several times the lift of the aerofoil in regular flight . More sophisticated aerodynamic analysis shows the bumblebee can fly because its wings encounter dynamic stall in every oscillation cycle . 
