DESIGN AND ANALYSIS OF A VARIABLE PITCH PROPELLER UAV FOR VTOL APPLICATIONS

This research presents the design, optimization, and validation of a Variable Pitch Propeller (VPP)–enabled Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV) optimized for high-altitude operations. The proposed platform addresses the fundamental limitations of fixed-pitch propeller UAVs, including reduced thrust efficiency in low-density environments, limited maneuverability during hover–cruise transitions, and constrained endurance.The UAV incorporates a swashplate-actuated servo mechanism to dynamically vary the blade pitch angle, enabling real-time optimization of angle of attack (AoA), thrust coefficient (Ct), and lift-to-drag ratio (L/D) across varying flight regimes. The propeller blades were designed using NACA 4412 and NACA 6412 airfoil sections for VTOL efficiency, with symmetric profiles evaluated for rotor stability. Aerodynamic performance was analyzed using a multi-fidelity methodology, beginning with Blade Element Momentum Theory (BEMT) and advancing to Computational Fluid Dynamics (CFD) simulations with Reynolds-Averaged Navier–Stokes (RANS) models in ANSYS Fluent. The VPP-based system demonstrated significant performance improvements, including increased thrust-to-power ratios in thin-air conditions, enhanced hover stability, and reduced power consumption during climb and transition phases. Comparative studies against fixed-pitch UAVs confirmed a marked improvement in high-altitude adaptability and endurance.This research establishes the viability of VPP-enabled VTOL UAVs as a next-generation aerial platform, with applications in atmospheric data collection, defense reconnaissance, search-and-rescue operations, and autonomous payload delivery in complex environments.