Conceptual Design and Finite Element Validation of Alpha-11 Wing: Mesh Convergence, Structural Performance and Material Trade-offs

This paper presents the conceptual design and finite element validation of the Alpha-11 regional turboprop wing, with a specific focus on identifying the most structurally efficient material configuration. The wing features a high aspect ratio, a tapered, moderately swept planform tailored to a 70–80-seat twin turboprop mission, and a three-dimensional finite element model is developed and evaluated under critical 2.5 g limit load cases dominated by bending and combined bending–torsion. A systematic mesh convergence study using successive refinements demonstrates solution independence, with changes in maximum von Mises stress and tip deflection below 5% between the final mesh levels. Using the converged model, a material trade-off is performed between an aluminium 2024-T4, Al 6061-T6, Al 7075-T6, and a carbon/epoxy unidirectional composite wing of identical external geometry. The results show that aluminium 2024‑T4 carries the design load, with a peak von Mises stress of about 17 MPa, a factor of safety of roughly 18, and a tip deflection of order 105 mm, offering adequate stiffness and a large stress margin at low material and manufacturing cost. In contrast, the composite wing roughly halves tip deflection and provides much higher stress margins, but at a substantially higher material and fabrication cost typical of carbon‑epoxy aerostructures. The study therefore identifies aluminium 2024‑T4 as the most suitable material for the Alpha‑11 conceptual design. At the same time, the composite configuration serves as a high‑stiffness benchmark that quantifies the structural benefits sacrificed to achieve a cost‑effective regional aircraft wing. The paper makes a combined study using a rigorous mesh convergence-driven validation framework with a quantified aluminium–composite trade study at the conceptual stage, demonstrating that a high aspect ratio aluminium wing can deliver superior structural designs while remaining compatible with the performance envelope of existing regional turboprop competitors like ATR 72-600, Dash-8 Q400, and MA700.