Captures air for the cooling system and turns the resulting installation into a net aerodynamic gain rather than a net loss.
The sidepod inlet is shaped and positioned to avoid ingesting front tire wake and to avoid competing with the undertray inlet. Inside, the sidepod maintains space for the oil or water lines, fans, pumps and sensors. On CR26I the sidepod was integrated into the undertray, which reduced weight and made manufacturing tolerances easier to account for.
Inlet shape and position chosen from CFD against tire wake and undertray inlet interference. The duct hooks the sidepod through matching lips; the sidepod itself mounts to the frame with two tabs and camlocks. From the design reports and one-pagers: The CR25 brief was to maximise the efficiency and packaging of a large radiator on the port side and an oil cooler on the starboard side, minimise drag while ensuring the cooling required for endurance running, and examine various radiator sizes to give powertrain a recommendation. Because the cooling setup is asymmetric there are effectively two separate designs, oil and water. The one-pager is honest that most of the initial design was completed without heat transfer to make up for lost time from equipment and access problems, and that the case for new sidepods rested on the moulds having maybe one more set left in them rather than on data.
Coast-down testing measured CD 1.33 with sidepods and 1.37 without, over five runs, so the ducted sidepods reduce whole-car drag. From the design reports and one-pagers: Validation per the one-pager: one mock endurance in coordination with powertrain as a practical test of the system, plus several constant speed runs measuring mass flow rate through the system at different speeds with either an anemometer or a pitot tube.
Tooling board milled and assembled to create a plug, fiberglass laid over the plug to create a mold, then an infusion layup on the fiberglass mold to create the part. From the design reports and one-pagers: CR25 one-pager estimate: create and machine mould stock for two sidepods, two ducts and two shrouds, 6 hours plus the drive to Knoxville and lead time from Reckless; fill and seal moulds 10 hours; lay up parts 40 hours; trim and mount parts 20 hours; clear coat 6 hours. Costs: fiberglass (2 oz, 6 oz and roving) $149.85, hardboard $7, fasteners $88.16, reflective tape $6, sealing foam $5.47, quarter quart of Bondo $4, Innegra $62.37.
CFRP.
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.
CR26I ducted sidepods: 4.37 lb as built against a 4.53 lb design estimate. From the cost report drawings and CAD: Weighed mass: 900.0 g (1.984 lb) (recorded as: Sidepods). Recorded masses spanning design variants, 6 values from 600.0 to 977.2 g; first three: 600.0 g (1.323 lb), 890.0 g (1.962 lb), 922.0 g (2.033 lb). Source: Subteam weight books: CR22/Aerodynamics/Manufacturing/CR22_Aerodynamics_Weight.xlsx Quantity per car, as costed: 2
Nothing in CrimsonStorage covers these yet.