At storytime, the children usually ask the questions. After reading a book about flying fish to his kids, though, Haecheon Choi, a mechanical engineer at Korea’s Seoul National University, was the inquisitive one.
Choi was intrigued by the gliding ability of these aquatic creatures whose versatile fins are also used as wings for out of water travel. Flying fish can remain airborne for 40 seconds at a time, covering distances up to 400 meters at speeds nearing 70 km/h. With the help of a colleague, Choi set out to test such impressive in-flight aerodynamics.
Choi caught, dried, and stuffed five flying fish, which he then fitted with sensors. Choi launched the fish through a wind tunnel to simulate flight, and measured the resulting forces on the fish’s fins and bodies.
As published Friday in The Journal of Experimental Biology, Choi found that the fins accelerate the airflow towards the fish’s tail, much like a jet. The resulting glide is greater than that of insects and comparable to certain birds. For the aptly named flying fish, being a fish out of water apparently isn’t so debilitating after all.