CR21 assembly line covering the fuel system.
Superseded by the Fuel Assembly grouping from CR22 onward.
No part-specific design process is documented. The Fuel subsystem design process applies: 1. Set tank volume from endurance consumption plus margin, with the HydraMat area and the tank CG as constraints. CR26: 1.4 gal cell, 1.56 gal effective system. 2. Design the sump to the acceleration cases: 1.42 g at 45 deg from vertical under acceleration against a rear wall 30 deg from vertical, and 2.51 g at 66.5 deg from vertical under braking against a vertical front wall. 3. Lay up the sump: 1 layer of Kevlar over 5 layers of stitched carbon twill on HIPS dissolvable molds, bonded with 3M DP420, sealed with Caswell epoxy gas tank sealer. 4. Design the top plate: -4 AN weld bungs instead of fittings, stud bulkhead terminals so no fuel path runs through wire, an aluminium terminal block for proper bulkhead seating. 5. Leak test the assembled system before it goes in the car.
From the Sphinx wiki fuel page: - No leaks, ever. Written as an absolute, with a larger sealing surface required on the top port if a top port is used at all. - Cornering. The tank must not be susceptible to fuel movement in corners, which was a live problem when the page was written and gets worse with wings: it cites 1.5 G consistently in skidpad with aero. Covering the entire bottom of the tank with the HydraMat is the documented fix. - Rubber line was ruled out on past reliability, specifically sealing and pressure retention. - Cost of materials and manufacturing time are both listed constraints on the design. - Endurance capacity is the functional constraint the 1.75 gal target came from.
From the cost report drawings: FINISH 1 (Vacuum Reference Bung); 6061 ALUMINUM (CR25 Fuel Cell Standoff).
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.
From the Sphinx wiki fuel page: - BMRS line replaced the previous plumbing. It supports higher pressure, has wear-resistant braiding, removes the need for hose clamps, and saved 0.256 lb. - Cell volume was raised to a 1.75 gal plus or minus 0.1 gal target after CR21's endurance fuel problem, with HydraMat coverage extended across the whole bottom of the tank to fix cornering pickup. - Open when the page was written: a fuel rail designed in house, covering mounting method, pressure sensor location, inlet and outlet ports and matching the injector port size to the chosen injectors; and an injector evaluation on duty cycle, characterisation data and port size.
Dimensions called out on the cost report drawings. These are the figures printed on the drawing, not a labelled specification; open the drawing itself for what each one refers to. Vacuum Reference Bung (as drawn): 1.27, 0.32, 1.11, 0.79, 0.16, 0.52 Carbon Fuel Cell (as drawn): 11.59, 39.69, R1.91, 7.93, 6.02, 13.61, 4.01, 9.23 CR25 Fuel Cell Standoff (as drawn): 16.00, 0.32, 0.64, 7.92, 6.60, 0.16, 16.18, 6.35, 1.75, 8.08 Source: Cost report drawings: CR22/Powertrain/Design/X - Cost Report Drawings/Manifolds/Intake/Vacuum Reference Bung.pdf; CR25/Powertrain/Design/Y - Cost Report Drawings/Fuel/CR25 Fuel Cell Standoff.pdf; CR25/Powertrain/Design/Y - Cost Report Drawings/Fuel/Carbon Fuel Cell.pdf; CR26i/Powertrain - IC/Design/Y - Cost Report Drawings/Fuel/CR25 Fuel Cell Standoff.pdf and 3 more Quantity per car, as costed: 1
Nothing in CrimsonStorage covers these yet.