Surprising behaviors in flapping locomotion with passive pitching

Thank you for your consideration of the manuscript entitled “Surprising Behaviors in Flapping Locomotion with Passive Pitching.” We were pleased to receive the positive feedback from the referees. In our revised submission we have made a number of adjustments in response to the referees’ comments and suggestions. In response to the first referee’s comments, we have added to the paper a short explanation of the linear relationship between horizontal velocity and flapping frequency in the clamped wing experiments, and have adjusted our statements regarding efficiency. In response to the second referee’s suggestions, we have added numerous comments and references regarding related work in the biological community. In particular, as suggested we have now included the resonant frequency of the immersed wing system in the experiments and numerics, which is found importantly to be near to the flapping frequency yielding the largest increase in lateral velocities. Also, instead of referring to the wing of previous consideration as “rigid”, we now refer to it as “clamped.”