The driver's primary control input and the mounting point for the switches and paddles they need while driving.
A CFRP half-shell on a CFRP structural backing plate, 9.22 in diameter, carrying six buttons, two 8-position rotary switches and TPU 3D printed grips, with an acrylic cutout so the dash is visible through the wheel. The rotary switches select traction control and launch control maps; the buttons handle driver radio, flag data, autoshift, cycle data pages, alt page, with one unmapped.
Diameter is a direct trade: larger diameter reduces hand force for the same steering torque, smaller diameter improves cockpit packaging and reduces hand travel. 9.22 in balances leverage, visibility and feedback. Travel is limited to +/-90 degrees so no driver has to go hand over hand.
Cockpit template. Dash visibility past the rim. Quick release must clear the 5 second egress requirement. Switch and button placement was called out as an improvement area in the anthropometric study. From the design reports and one-pagers: Diameter must not be larger than the old wheel at 9.225 in to remain rules compliant. Rules: V.3.3.1 in any angular position the wheel must meet T.1.4.4. V.3.3.2 the wheel must attach to the column with a quick disconnect. V.3.3.3 the driver must be able to operate the quick disconnect in the normal driving position with gloves on. V.3.3.4 the wheel must have a continuous near-circular or near-oval perimeter; straight sections are allowed but concave sections are not, and H, figure 8 or cutout wheels are prohibited. T.1.4.3 all vehicle controls must be operable from inside the cockpit without any part of the driver being outside the side impact structure. T.1.4.4 all vehicle controls must stay below the topmost point of the front hoop in any operational position.
Static steering force calculated as T = F*r: 5.963 lbf at a 4.61 in radius gives 2.290 lb-ft. Checked against NASA anthropometric data for critical operations (18 lbf arm up, 22 lbf arm down).
CFRP half-shell laid up over a structural backing plate. Grips 3D printed in TPU. Switched to an 8-pin connector.
CFRP shell and backing plate, acrylic insert, TPU grips.
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.
Customised per-driver grips were attempted from driver hand molds, but driver preference converged on a single design, so the customisation was dropped.
9.22 in diameter, +/-90 deg travel. Static steering force 22.80 lbf on CR26I base setup, against 25.36 lbf on CR25 and 37.53 lbf on CR22 base (88.39 lbf at CR22 maximum caster). From the cost report drawings and CAD: Chassis weight breakdown: CR25 3.500 lb, CR26E CAD 0.801 lb. Source: CR26E/Systems/03 - Mass Model/ChassisWeightBreakdown.xlsx Quantity per car, as costed: 1