Optimal Design of a Transitional Rotor Blade for Agricultural Unmanned Rotorcraft using SAS

Recently, the adoption of unmanned rotorcraft systems in agriculture has attracted increasing attention. The aim of this study is to investigate the optimal operating condition of hovering with the transition blades, progressively formed with two basic airfoils, and to select the optimal twist angle accordingly. Response surface regression process (Proc RSREG) of SAS was used as an effective tool in the optimization of the simulation results, using multiple reference frame methodology via ANSYS Fluent. As a multi-objective design, the torque was limited to 63 % of the available power (24 kW, 1,000 rpm) of the agricultural rotorcraft. From a stable design point of DP2 (GPA = 15 degrees, twist angle = -11.8 degrees) to a conservative design point of DP4 (GPA = 10 degrees, twist angle = -4.9 degrees), designs were selected. Then, the transitional blades were fabricated, and the payloads of 569.0 N and 539.6 N were evaluated, respectively.