This paper proposes a method to enhance the load capacity and reduce the volume of an Unmanned Aerial Vehicle (UAV) by optimizing the motor’s KV value (a measure of RPM per volt) to match the specific aerodynamic characteristics of a multi-blade propeller system. Given the fixed maximum output power of the motor when its volume and weight are determined, a higher-power-density motor structure can maximize blade lift by optimizing its output torque and speed. The electromagnetic structure of the motor is initially designed based on the aerodynamic characteristics of a 29-inch, four-blade model. Different motor Voltage-Turns (KV) value schemes are obtained by altering the number of winding turns and the wire diameter. Subsequently, the torque–speed output performance of the motor is calculated under constant power conditions. This data, in conjunction with the blade load, allow for a comparison of the motor’s output lift at different KV values. The optimal KV value for the motor is determined to be 116, resulting in a rated lift of 11.57 kg. This paper correctly analyzes the motor and blade as an integrated system, which is crucial for meaningful optimization in aerospace application.

Tip leakage degrades ducted fan performance and contributes to unsteady loading noise. This study investigates a wall-penetrating blade ring (WPBR) ducted fan for unmanned electric vertical takeoff and landing (eVTOL), replacing radial clearance with axial end face gaps. Six configurations of a 381 mm four-bladed rotor were evaluated at 5000 r/min under quasi-hover conditions: a conventional ducted fan, an internal blade ring rotor, and four WPBR cases with single-sided clearances of 0.8–2.0 mm. Sliding-mesh unsteady Reynolds-averaged Navier–Stokes simulations using the shear stress transport k-ω model were coupled with the Ffowcs Williams–Hawkings formulation. The WPBR formed a U-shaped cavity recirculation and redistributed the concentrated tip-region vortical structures. The 1.2 mm case retained 28.72 N of thrust, 2.1% above baseline, while reducing torque by 6.1% relative to the 0.8 mm case; its figure of merit remained lower. Its simulations predicted a reduction of 16.4 dB in the first blade-passing frequency level in the rotor plane and a predicted reduction of up to 15 dB in overall sound pressure level at 1 m. Thus, it represents a compromise among thrust, torque, and predicted acoustic performance rather than an aerodynamic optimum. A magnetically supported prototype operated up to 2000 r/min, demonstrating low-speed operability of the architecture for unmanned eVTOL propulsion.