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.