This study presents a flight-envelope-based methodology for aerodynamic load assessment and composite material selection applied to a hybrid fixed-wing tri-rotor VTOL (Vertical Take-Off and Landing) unmanned aerial vehicle (UAV). A certification-oriented maneuver and gust envelope was established to define the critical load cases. Reynolds-averaged Navier–Stokes (RANS) simulations of the full aircraft at nominal cruise were performed to determine global aerodynamic coefficients and distributed pressure fields, including interference effects from the fuselage and externally mounted VTOL system. A complementary wing-only angle-of-attack study was used to characterize lift, drag, and chordwise pressure distributions over the relevant incidence range. Critical envelope points were mapped to equivalent aerodynamic states in terms of lift coefficient and angle of attack, enabling a quasi-steady correlation between certification loads and CFD (Computational Fluid Dynamics) results. In parallel, carbon fiber-reinforced polymer (CFRP) laminates were experimentally evaluated under tensile, open-hole tensile, and flexural loading. The results indicate that, within the two investigated laminate configurations, the 0°/90° CFRP laminate provides the more suitable strength and stiffness for primary wing structures, while off-axis laminates are better suited for secondary regions. The proposed workflow links flight-envelope definition, aerodynamic analysis, and material selection, providing a basis for preliminary structural design.
Badea et al. (Tue,) studied this question.