Nezha‐SeaDart: A tail‐sitting fixed‐wing vertical takeoff and landing hybrid aerial underwater vehicle

This paper presents the design, manufacturing and testing of a tail‐sitting vertically takeoff and landing fixed‐wing hybrid aerial underwater vehicle (HAUV) called Nezha‐SeaDart. Nezha‐SeaDart can vertically take off and land from ground and water, cruise in the air with lift generated by the wings, seamlessly cross the water–air interface and operate underwater like an autonomous underwater vehicle. Nezha‐SeaDart underwent a 10‐day field test in China's Thousand Islands Lake of Zhejiang Province, proving its ability to perform full cross‐domain missions. This research has the following contributions to the field of HAUV. (i) A working prototype of vertical takeoff and landing tail‐sitting HAUV with all basic functions verified and full mission cycle capability demonstrated in a field test. (ii) An HAUV that travels fast both in the air and underwater. (iii) An HAUV capable of autonomous and seamless water exit that does not rely on a dedicated propulsion system. (iv) A method of sizing the vehicle's wing and thrust considering aerial cruises, underwater operations, and seamless water exits.