FSAE | INTERNAL STRUCTURES & PACKAGING

Under extreme aerodynamic stresses, a wing's internal ribs and spars are what hold it together. Previously, these were complex 3D structures (curved I-beams and C-channels). These were structurally efficient but a nightmare to manufacture and even worse to assemble. They required separate molds, were extremely difficult to layup perfectly against sweeping wing contours, and depended on sequential placement during bonding. This caused massive tolerance stack-up issues. Thermal expansion, imperfect prep/layup, and excessive bonding surfaces meant using heavy adhesive and poly-filler to fix gaps, destroying our weight margins.

To guarantee we could reliably hit our tight production timeline, I pivoted the internal spars and ribs to 2D flat-stock carbon fiber plates. While curved I-beams are stiff, flat plates don't require molds, they are laid up flat on a table, which completely significantly reduces scrap rate and other massive layup complexity. The only curved regions were precision-cut using a waterjet so you know they are true to CAD. To compensate for the slight drop in geometric stiffness against the curved alternatives, we implemented a 5 ply spar.

To fix the sequential tolerance stack-up problem, I engineered an interlocking cross-lap joint system. The flat-stock ribs and spars featured opposing slots that acted as a self-aligning mechanical fixture. Instead of parts stacking sequentially and pushing tolerances outward, every rib effectively 'clips' mathematically onto the main continuous spar. We used Hysol EA 120 structural adhesive to lock the joints—cutting down layup and assembly time significantly.

The front wing leading edge is the first point of impact. In the past, brute-force carbon or brittle foams would shatter completely on a cone strike, and Kevlar would frill, making surface repairs impossible. After evaluating 13 different foam options for the leading-edge core, I selected Corecell M80. It possesses a 40% elongation at break, meaning its compressive and absorption strength allow it to deform and absorb energy plastically beneath the carbon skins rather than fracturing catastrophically.