Impact of the pectoral fin geometry on the gliding performance of flying fish robot

Abstract

Flying fish, as a quintessential cross-medium species, are well known for their exceptional underwater swimming and water–air transition capabilities. However, their aerial gliding kinematics — particularly the influence of pectoral fin morphology on gliding performance — remains insufficiently explored. In this study, we develop a bio-inspired gliding model to investigate airborne gliding characteristics. Four pectoral fin designs based on distinct biological morphologies (Model A: flying fish; Model B: devil ray; Model C: puffin; Model D: pigeon) were fabricated, and their aerodynamic performance was evaluated through hand-throw tests, catapult-based gliding experiments, and CFD simulations. By varying the angle of attack and launch velocity, we systematically analyzed their effects on gliding efficiency, while numerical simulations were conducted to further assess aerodynamic forces and predict gliding dynamics. Results show that under a 20° angle of attack and a launch speed of 13 m/s, the flying fish inspired fin (Model A) achieved a maximum gliding distance of 5.97 m, which is 8.74%, 10.97%, and 11.38% longer than the other three models. The launch energy required per unit gliding distance was also reduced by 8.83%, 12.36%, and 11.52%, respectively. Both experimental and numerical findings confirm the superior aerodynamic performance of the flying fish pectoral fin in aerial gliding. This study provides insights for the future development of bio-inspired flying fish robots capable of air gliding.

Keywords

Flying fish / Aerial gliding / Pectoral fins / Catapult-based experiment / Bio-inspired design

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