Similarly, as is shown in Fig. 3(b), when the glider is diving, wings rotate upward. There exist a relationship between the lift/drag ratio and the wing incidence angle φ . If φ is probably chosen, this would lead to greater lift/drag ratio than conventional fixed-wing underwater gliders and improve the motion performance of the glider. The maximum rotation angle of the wings can be set beforehand to achieve the best performance. Three-dimensional CAD software 'SolidWorks' was introduced to gain 3D model of the experimental underwater glider. Fig. 4 shows an example of 3D model of the glider. The hull of the underwater glider is made of plastic of 4.5mm thick. Wings are made of organic glass of 2mm thick. The weight of the ballast is 1.7kg. It can be moved back and forth to adjust longitudinal position of the centre of mass. Then the glider will nose up or down. There also exist a space of about 200mm in the front portion of the glider for sensors and microcontroller.