Autonomous Underwater Gliders

This chapter discusses the characteristics, design considerations, and performance of autonomous underwater (UW ) gliders. These buoyancy-propelled, winged vehicles can be categorized as: (1) profiling gliders that traverse in bobbing trajectories to collect vertical profiles of ocean properties and (2) cross-country gliders designed for point-to-point horizontal transport efficiency. Horizontal transport efficiency is quantified by net transport economy and specific energy consumption. The latter metric for a glider is equal to its inverse lift-to-drag ratio (also called finesse) and is equivalent to the glide slope in steady-state, nonturning glides. Increases in efficiency can be obtained by: 1. Increasing the loaded mass (with larger buoyancy engines) and increasing the overall size of the glider, which increases the glider’s speed and maintain sufficiently high Reynold’s numbers to avoid the drag crisis. 2. Reducing the ratio of the total vehicle wetted area to wing area, via use of flying wing or blended wing body shapes, and 3. Increasing the wing aspect ratio, within structural strength and stiffness limitations.