To close out the external surface of the car: cover the frame, route air over and around the vehicle rather than through it, shield the driver and hot components, and carry the team livery.
Thin CFRP panels bonded and fastened to frame tabs form a continuous outer surface from the nose cone back over the sidepods to the engine cover. The nose cone caps the front bulkhead and works with the front wing to control what air reaches the undertray inlets. Side panels close the sides of the cockpit; the engine cover closes the rear. Because CR26I moved to a center-tunnel undertray, the nose could be shifted away from the previous low-nose arrangement, which had been forcing ride height up to avoid contact with the track.
Bodywork is a mass problem before it is an aerodynamic one. It produces little downforce on its own, so the design driver is minimum laminate weight consistent with handling loads and surface quality. CR26I bodywork came in at 2.96 lb as built against a 4.46 lb design estimate. The standing process: mill or 3D print a mold, lay up, post-process, then check the panel against the full-car CAD before it goes near the frame. 1. Take the outer surface from the aerodynamics CFD geometry so the panel is the same surface that was simulated. 2. Choose a laminate schedule using the team's laminate weight calculator, trading ply count against stiffness and surface finish. 3. Mold: tooling board milled on the 5-axis gantry for large surfaces, 3D printed molds for small parts. Automotive clearcoat over the print cut roughly 22 hours of sanding and made the molds reusable. 4. Layup and cure, then post-process, fill the leading edges with polyester filler and satin clearcoat for UV protection. 5. Test fit on the frame, then trim and drill mounting hardware to jigs.
- Reduce panel mass without losing surface quality or stiffness. - Keep the external surface faithful to the CFD geometry so validated coefficients still apply. - Make panels quick to remove for service; camlocks and tab mounts rather than fasteners that need tools. - Reduce mold and layup hours each cycle.
- Warped molds. CR25's undertray mold warped badly enough to be unusable, which is what forced CR26I onto a cross-compatible EV part. Fiberglass molds pulled from CNC-machined foam plugs were the root cause; moving to directly machined high-density tooling board fixed it. - Surface finish from 3D printed molds. Solved by spraying and sanding automotive clearcoat over the print. - Panel damage from track incidents. CR25's undertray was damaged during summer testing, which removed the option of reusing it.
ANSYS Fluent for the external surface (shared with the rest of the aerodynamic package). SolidWorks for panel geometry and fitment against the full-car CAD. The team laminate weight calculator for schedule selection. Tensile testing on an MTS load frame with arrow-profile end tabs for layup schedule characterisation.