Beam Design Optimization of a Tandem Wing Aircraft

A Python–FreeCAD automated program was developed to optimize spar cross‐sections for tandem‐wing UAV applications under set deflection limits. Initial I‐beams and C‐channels were generated based on spanwise lift distributions from XFLR5 and analyzed using a simplified 2D beam bending model. Cross‐sectional inertias were calculated via the parallel‐axis theorem, and masses were obtained directly from FreeCAD volume queries. A non‐destructive, monotonic

“geometric sweep” optimizer reduced each section’s inertia by 5 % per iteration until the calculated deflection precisely met the target span‐to‐deflection ratio of 12/67% to

five‐decimal‐place accuracy. The final flange and web dimensions were then reconstructed in CAD and extruded to the appropriate lengths, with STEP exports produced for both the baseline and optimized beams. Results showed significant mass savings while maintaining structural

stiffness, the optimized beams achieved target deflections without overshoot, and the original designs we preserved for side‐by‐side comparison.