The aerodynamic efficiency of small unmanned aerial vehicle (UAV) propellers is affected by losses arising from tip-vortex formation. At the blade tip, pressure differences between the suction and pressure surfaces induce vortical structures that increase induced losses, reduce effective thrust generation, and degrade propulsive performance. Mitigating these tip-related losses is critical for improving the efficiency of small-scale propellers operating at low Reynolds numbers.
This work presents an investigation into the effectiveness of blade-tip winglets as a passive flow-control technique to reduce thrust losses in a seven-inch propeller. Three distinct winglet configurations were examined: a canted winglet, an up/down wingtip fence, and a wingtip fence. All winglet geometries were designed using the NACA 4412 airfoil profile to ensure geometric consistency and aerodynamic characteristics. The baseline propeller and the winglet-integrated variants were modelled using CATIA V5 and fabricated from ABS material via fused deposition modelling.
Experimental evaluation was conducted using a custom-designed thrust measurement rig. Thrust data were acquired over a speed range of 4000 to 6000 rpm under repeatable conditions. Each winglet configuration was tested independently and compared against the baseline propeller to quantify performance improvements.
The results demonstrate that the incorporation of winglets leads to a measurable increase in thrust across the entire operating range. The canted winglet configuration yielded the most significant improvement, with thrust increases of 71% at 4000 rpm, 24.6% at 5000 rpm, and 32.8% at 6000 rpm, indicating superior suppression of spanwise flow and tip-vortex strength. The wingtip fence showed moderate thrust increases of 42%, 16.6%, and 10.7%, while the downward wingtip fence exhibited smaller but consistent increases of 13%, 8.7%, and 5%. Overall, the study establishes winglet integration as a simple, low-cost, and effective method for improving the aerodynamic performance of small UAV propellers.