Bio-inspired aquatic flight propulsion system for agile and manoeuverable underwater vehicles

Modern unmanned underwater vehicles generally use one of two methods for manoeuvring; thrusters or control surfaces. These control methods each have a limited range of speeds over which they can operate efficiently. Manoeuvring control is often separate from the propulsion system, increasing vehicle weight and drag. By comparison, many animals possess only one set of propulsors which is used for both propulsion and manoeuvring. There are many types of marine animal locomotion, aquatic flight stands out for having both high speed and very good manoeuvrability and is the focus of the present research. The investigation uses a combination of animal video motion analysis, mathematical modelling and experimentation. Video motion analysis was used to provide data on the actual motion made by a penguin wing during swimming motion. Of particular interest is the yaw motion of the wing, however the ability to accurately capture this axis of motion was hindered by the video quality. The mathematical modelling concentrated on the Blade Element Theory (BET). The model was used to assess the loads generated by the motion of a wing section. In additional to the hydrodynamic lift and drag forces, the BET model also modelled added mass forces and Kramer effect. However, the result the model still under predicted the thrust coefficient suggesting the thrust is supplemented by other hydrodynamic effects. The BET model was also used for analysis of three axis actuation where it found the yaw motion will reduce thrust coefficient. Finally a three axis experiment has been designed with inspiration from the motion observed from swimming penguins and the experiment will be used to validate the forces from the mathematical model.