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MSXV Approach:
Place your person + battery box in boundary box → placement and ergonomics (how they will be seated, how the box will be oriented)
Solar Array → Objective should be to maximize 4m^2 limit for array
Place Wheels
Rough Chassis → General body shape, keepouts and boxes for dynamics components
Rough Aerobody
Timeline Notes:
MS12 took 8 months for all designs (Jan 2017 CAD, Oct Design Freeze, Dec end rolling chassis)
Panel Manufacturing - 8 month process start to finish for MSXV (Shalin)
Rolling Chassis is the most important (Adam, Shalin, Adrian) - 8 months from start to rolling chassis?
Fit checks, tolerances and unforeseen circumstances will be uncovered once this is achieved
Solar Array Notes:
Vehicle objective should be to maximize array, it is the only way we can power our vehicle (Adam, Shalin)
Array can only bend in one direction (one curve plane)
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Canopy:
Hinge should be behind driver (Shalin)
Canopy will be wider than the persons head and solar array will need to be placed around that
Perhaps ventilation through gaps in canopy for driver (Adrian)
Aerobody Geometry:
Catamaran will be more efficient aerodynamically, bullet is like big wall in front of air (Shalin)
Aero chassis integration:
Should not be an afterthought
Base studs/clickbond was not a great approach in tension, but work well when placed right (in shear) (Shalin, Adam)
Surface prep of panel and mold is needed to make things stick
OTS solution that's cheap is best, would be one less thing to design (Adam)
Aero Panels and Molds:
Practice practice practice
Polish the mold very well, any features/gauges/indents will reflect on your panel
Vacuum infusion:
MS12 used polystyrene/foam for molds, was lots of work to prep
MS12 locked down the Aerobody with 7 months to competition
Mold making took 1 month (suggested 50% of time - part 1)
Mold polishing took 1 month (suggested 50% of time - part 2)
Laying the parts took 1 month (suggested 25% of time)
car installation took 1 month (suggested 25% of time)
Overall very rushed!!!!
If making molds in house, allocate a whole term to just making them (Shalin)
Axium cures at 70C (Adam)
“characterize infusion process” (Adam)
2 or 3 good pulls
Chassis Notes:
Chassis syms (Ansys, symscale):
Static loading
fix the wheels for a top load/impact, fix the back of the car for a front impact
5G crash tests with blocks, see if it deforms past allowable amount and doesn't exceed F.S.
Use FEA to determine where we need bulkheads (composite bulkheads are very good - Adam, Adrian) or more triangulation
Skeleton work, geometry and sketches
CFD is challenging
The faster chassis is in CAD the better
Design for how much room battery box needs
Dynamics Notes:
Double wishbone suspension:
Very easy to adjust camber, castor and toe (Adam)
More moving parts (may be more difficult)
Adam has a confluence page for suspension types
Where will the motors be?
Torque and weight considerations
MS14 hub motors are very high end (Adam)
How do we break?(Adam)
Front breaks do most of the work, break bias can be adjusted
4 wheel breaking is critical, with redundancies across the front
Breaking force distribution, 60% front, 40% rear, dragging calipers will do more work
Active steering point
Battery Box Notes:
Cooling system is very important
Active velocity based cooling?
Need to be removable
Power consumption and battery type determine volumetric requirements
Competition Notes:
MS12 was not comp ready, lots of electrical bugs, very inconsistent, communication was not robust
MS12 had lots of last minute FSGP tweaks
MS12 battery faulted when it shouldn’t have