High-speed robotic albatross : unmanned aerial vehicle powered by dynamic soaring

Abstract

Wandering albatrosses exploit the vertical gradient of wind velocity (wind shear) above the ocean to gain energy for long distance dynamic soaring with a typical airspeed of 36 mph. In principle, albatrosses could soar much faster than this in sufficient wind, but the limited strength of their wings prevents a much faster airspeed. Recently, pilots of radio-controlled (RC) gliders have exploited the wind shear associated with winds blowing over mountain ridges to achieve very fast glider speeds, reaching a record of 498 mph in March 2012. A relatively simple two-layer model of dynamic soaring predicts maximum glider airspeed to be around 10 times the wind speed of the upper layer (assuming zero wind speed in the lower layer). This indicates that a glider could soar with an airspeed of around 200 mph in a wind speed of 20 mph, much faster than an albatross. It is proposed that recent highperformance RC gliders and their pilots’ expertise could be used to develop a high-speed robotic albatross UAV (Unmanned Aerial Vehicle), which could soar over the ocean like an albatross, but much faster than the bird. This UAV could be used for various purposes such as surveillance, search and rescue, and environmental monitoring. A first step is for pilots of RC gliders to demonstrate high-speed dynamic soaring over the ocean in realistic winds and waves.