Attach the undertray to the frame at the inboard points and resist aerodynamic loading and longitudinal translation.
Double-shear mounts with quick removal. Dog bones in the mount allow ride height and rake to be adjusted independently of the chassis, so Suspension can change setup without moving the aerodynamic platform.
No part-specific design process is documented. The Undertray/Floor subsystem design process applies: 1. Sweep tunnel geometry parametrically in CFD: expansion ratio, choke height, inlet shape, outlet length. Findings were peak efficiency at expansion ratio 5.14, peak downforce at 5.44, flat inlets greatly reducing drag, greater choke heights helping, and outlet length having little effect. Stall is the limit. 2. Add the center tunnel where packaging allows. CR26I outboard tunnel width fell from 11.63 in to 6.94 in because of the wider EV frame, so the center tunnel recovered the lost area. Center section efficiency 25.2, outboard 12.6 on Iter17. 3. Check the design against the aero no-go surface derived from worst-case heave and roll with Suspension. 4. Package around the exhaust, oil pan, jack bar, radiators and sidepods, with inlets and outlets positioned away from direct tire effects. 5. Validate on track with Flo-Vis on the bottom surface and constant-speed CL measurement.
Milled rather than waterjet, because the waterjet surface finish leaves stress raisers that can propagate. Inboard hardpoint placement uses 3D printed jigging adjusted for laminae thickness so the hardpoint is positioned relative to the mold.
Aluminium brackets, aluminium hardpoints within the laminate.
None recorded. This part has no entry in Knowledge_Transfer/Issue Logging/Fault Vault.xlsx, in either Issue Log.xlsx, in CR22/Issue Tracking/Shakedown 7-15-23.xlsx, or in any design review issue list found in CrimsonStorage or Box.
The CR25 inboard mounting was inaccessible, which made removal slow. CR26I revised it specifically to improve attachment and removal time.
CR26I inboard mounting 0.556 lb at a 486 lb load requirement, against CR25's 0.889 lb at 400 lb. Quantity per car, as costed: 4
Nothing in CrimsonStorage covers these yet.