Practical modification for low Reynolds number propeller applications

Abstract

Applications for Unmanned Aerial Vehicles (UAV) and, specifically, Micro Aerial Vehicles (MAV) are increasing. As is the case for all aircraft, propulsion plays a significant factor in overall vehicle performance. Most small UAV or MAV propellers are commercial, off-the-shelf products given their availability and low cost. Unfortunately, the off-the-shelf propellers are not tailored to a specific vehicle and/or mission. Only limited technical and performance data is available for the propellers. A number of modifications have been used on larger (manned) aircraft propellers and rotors in the past to improve performance. Examples of possible modifications include vortex generators, cut tips, and tip sails. An investigation was conducted with the following goals: 1. Experimentally measure the performance impact of various modifications on UAV/MAV-class propellers 2. Study the practical applications for such modifications to UAV/MAV's 3. Evaluate the utility of related propeller performance prediction tools Experimental and basic analytical investigations address these goals. Special emphasis was placed on studying simple, practical, and cost effective modifications. This investigation shows that after testing 24 modifications a number of practical modifications to improve propeller performance do exist. 2-Propeller, leading edge notches, and Gurney flap modifications all improve thrust while leading edge notches and Gurney flap modifications also improve cruise efficiency.