UTAT wing MDO — Mason Shopperly

Problem

SAE Aero Design scores payload, so every choice in a competition aircraft wing is a trade against take-off weight, structural margin, manufacturability, and the competition rules. You cannot decide these one at a time. On the UTAT SAE Aero team I led wing aerodynamics and helped build a simple MDO loop for the aircraft so that aero, structures, and constraints could move together.

Approach

The loop coupled nonlinear lifting-line theory for spanwise loading with beam-bending spar sizing, wrapped in a small MATLAB optimiser around planform geometry and competition constraints. XFoil and XFLR5 supplied airfoil-level performance checks. The goal was MTOW and payload maximisation subject to stall, manoeuvrability, and structural limits, with results legible enough to be challenged by other leads.

From-equations-to-hardware was the whole point. Lift distribution changes mean spar deflection changes; airfoil choice changes mean a different trailing-edge thickness in balsa and ply; aspect-ratio sweeps have to stop where manufacturability stops. The MDO loop was a way to make those couplings visible rather than implicit.

Result

A final planform — span, taper, aspect ratio — that met competition constraints with deliberate structural margin, paired with an airfoil chosen for high lift with a forgiving stall and a trailing edge that could actually be built. The MDO loop made the aero–structural trade visible: changes in aspect ratio and chord distribution came with explicit numbers for payload potential and spar demand, and every major choice was handed off to structures and manufacturing with a rationale attached.

Through two design–build–fly cycles, the analysis choices showed up in assembly and flight behaviour. Some trades held; others moved.

What I’d do differently

Earlier engagement with manufacturing. The cleanest aero choice is not the right one if the build schedule cannot absorb it, and I would now spend the first design week in the shop with the structures and build leads before the first lifting-line run.

Spar bending moment + deflection (top), torsion + torsional deflection (bottom), vs span y — Spar bending and torsion — beam-bending output of the MDO loop. Bending moment and deflection (top); torsion and torsional deflection (bottom).

Laser-cut sheet — UTAT wing ribs and ailerons, DXF nest, red linework on white — Cut sheet — ribs + ailerons. Nested for stock yield; the rib pattern is the MDO output translated into a knife path.

Laser-cut sheet — UTAT wing spars, DXF nest, red linework on white — Cut sheet — spar laminae. Lightening pockets sized against the bending/torsion plot above; this is what the analytical loop becomes once the team is at the laser.

Three UTAT team members assembling a balsa wing structure by hand — Building the wing — hand-assembling the balsa truss-rib structure during the UTAT build.

Mason with the UTAT Aero competition airframe — Aircraft 213 — the airframe the loop was tuned against.

Minerva at tech inspection — Minerva at competition tech inspection.