Hydrobatics, the underwater analogue of aerobatics,
enables agile maneuvers that extend the operational envelope
of Autonomous Underwater Vehicles (AUVs). In this paper,
we present a trajectory optimization approach for perform-
ing hydrobatic maneuvers and out-of-water jumps with the
Arrow AUV, a lightweight, low-cost, flight-style vehicle with a
Thrust-to-Weight Ratio (TWR) above three. Feasible trajectories
for the underactuated vehicle are generated offline via direct
transcription and stabilized online with a Time-Varying Linear
Quadratic Regulator (TVLQR). We demonstrate on-the-spot
pitch-up maneuvers, vertical hovering, and water-exit jumps into
ballistic flight, both in simulation and on real hardware in a
saltwater test basin. To the authors’ knowledge, this is the first
demonstration of a flight-style AUV jumping out of the water,
bridging the gap between AUVs and aerial-aquatic transition
vehicles.