Aerodynamic Performance of a Hand-Launched Biplane UAV with Distributed Electric Propulsion

Hand-launched unmanned aerial vehicles require adequate low-speed lift and cruise efficiency. This study investigates a 3 kg propeller-aided biplane (PAB) with distributed electric propulsion using unsteady computational fluid dynamics. Propeller–wing arrangements are examined, followed by complete-aircraft simulations with transition modeling and sliding meshes. A conventional tractor configuration (CONV) provides a reference under comparable design constraints. Among the arrangements examined, over-the-wing and leading-edge tractor installations provide substantial lift augmentation. Predicted airframe loads are sensitive to transition modeling and the representation of propeller rotation. Although PAB has a lower clean-airframe lift-to-drag ratio, its smaller propeller-induced airframe drag penalty largely offsets this disadvantage at sampled fixed-rpm cruise conditions. At the 5 m/s hand-launch condition and angles of attack of 8–12°, PAB provides greater lift per unit shaft power with a comparable positive net forward force. At 12°, the lift-per-power gain is approximately 4%. About the respective design reference centers of gravity, cycle-mean nose-down moment magnitudes are approximately 77% and 49% smaller for PAB than for CONV at 8° and 12°. These predictions indicate hand-launch benefits for this non-optimized configuration pair under the prescribed conditions.