Feasibility study on mimicking the tail-beating supported gliding flight of flying fish

Abstract

Mimicking the unpowered gliding capabilities of flying fish is challenging, due to the various technical limitations that are involved in creating a dual-modal robot that can both swim underwater and fly in the air. In this work, we suggest a modified KUFish design equipped with a pair of foldable wings for gliding flight in the air. Although the current water-leaping speed of the KUFish is lower than that of flying fish, the robot may be able to lift off by taking advantage of a head wind and forces produced by tail-beating motion, compensating for its weight, and overcoming the drag. Our series of computational fluid dynamics simulations has shown that with the unfolded wings and fully submerged tail-beating motion, when the wing and body angles are maintained in specific ranges under the head wind speeds of (9.5 and 6.5) m/s, the robotic fish after water-leaping can perform efficient gliding flight without generating pitching moment. This work can also be used to explain how flying fish perform gliding flight under tail-beating motion, and to develop an actual model of the dual-modal robot that mimics flying fish in the future.