Abstract:
Rotor blade optimization with blade airfoil Reynolds numbers between 100,000 and 500,000 - characteristic of radio controlled (RC) helicopters - was performed using Blade Element Momentum theory (BEMT) and demonstrated via flight tests. BEMT was used to test various airfoil profiles and rotor blade shapes using airfoil data from 2D Computational Fluid Dynamics (CFD) simulations with Reynolds numbers representative of the blade elements. A blade design utilizing a cambered profile, taper and twist was developed for increased performance in hover. Selected blade designs were manufactured and flight tested on a Blade 600X RC helicopter (671 mm blade radius) to validate the theoretical results. The best of the improved blade designs increased the Figure of Merit (FM) by 20% and reduced power consumption by 22% while keeping the rotational frequency constant. Reducing the rotational frequency from 2,000 to 1,500 RPM resulted in an additional 55% increase in the FM and 35% reduction in the power consumption, while a one-bladed design further improved endurance and range performance of the helicopter by as much as 20%. The presented results could serve as useful guidelines to small Unmanned Aerial Vehicle (UAV) helicopter manufacturers and operators for increasing endurance, range and payload capabilities.