ALBATROSS: A bioinspired, aerially deployable, autonomous sailing sensor platform.

Rapid deployment of autonomous sensor platforms in remote aquatic areas remains a challenge for environmental monitoring, disaster response, and ocean science. We present ALBATROSS (Airborne Lander with Buoyant AuToROtating Sailing Sensor), a hybrid bioinspired robot that passively autorotates for soft water landing and transitions into a wind-driven sailboat. Its dual-function rigid wingsails, acting as both sails and autorotating wings, enable efficient descent and propulsion. A freely rotating main sail, controlled by a tail rudder, and a directly actuated front sail enhance thrust and aerodynamic stability. A biomimetic caudal fin-inspired rudder enables propulsion during low-wind conditions and agile maneuvering in challenging upwind tacking. We empirically evaluated different wingsail airfoils through wind tunnel testing and optimized rudder design through hydrodynamic modeling, material selection, and speed-power efficiency analysis across different sizes and stiffnesses. Field experiments validate aerial deployment from 150 meters, autorotating descent, passive self-righting, and successful waypoint navigation using both rule-based control and a reinforcement learning approach. By integrating minimal actuation, bioinspired structures, and passive dynamics across aerial and marine operating regimes, this work extracts generalizable design principles for lightweight, aerially deployable sailing robots capable of robust, energy-efficient marine sensing.