Aerodynamic Simulation of a Cargo UAV with Twin-Boom and Rear-Mounted Propeller

The propulsion of a rear-mounted propeller is a practical option to feature an inverted V-tail in unmanned aerial vehicles (UAVs). The slipstream of the propeller is crucial to the static stability and has interference on aerodynamic characteristics between the propeller and other parts. A twin-boom cargo UAV with an inverted V-tail and rear-mounted propeller is proposed to investigate the effect of the propeller by numerical methods. In this study, the K-ε viscosity model and MRF model were utilized to calculate the aerodynamic performance of the initial and motored UAV models, respectively. The aerodynamic performance and static stability are compared at different angles of attack and sideslip angles for clean and propeller-motored configurations. The results show that the rear-mounted propeller can increase the thrust coefficient by 27.9% under a rotational velocity of 6000 RPM, which leads to a drag increment in the fuselage and apparently delays the separated flow. Although the interference of the slipstream is weakened by the configuration of the inverted V-tail, it still has an adsorptive effect on the lower side of the tail. We found that asymmetric interference is the primary cause of the decrease in longitudinal and directional static stability. Finally, a model airplane was made to carry out flight experiments and confirm the above results.