Designing
an adequate floor system was quite a challenge. There are so many
requirements for this critical part that it took me months to finally
settle on a beefy bolted down rail structure.
And,
as usual, safety was a key driver. Since it will be holding two 300lbs
battery trays, a glued down floor was out. It needs to withstand the
brutal conditions of a space launch, and the wrath of divinities 😂
- Minimum 20 yrs of safe operation
- Massive holding power in 3 axis (in case of a crash or flip)
- Compliant and predictable response to longitudinal twisting (a van floor twists constantly, especially on uneven surfaces)
- Resistance to corrosion (road & sea salts)
In the end, I settled on laying down six 1.5" U channels. They provide both the sliding and secure anchoring functions for the trays and cabinets that will be mounted on the floor:
Time for sparks to fly ! Back to back rails were welded together to help with keeping the floor surface as flat as possible, and to double the holding power
of the assembly per bay in case of a crash. The rails were then
precisely spaced thanks to 4 welded transversal flat bars, to ensure a
consistent fit for the sliding trays, and for the subfloor panels at the
front.
Before
laying down the rails, the floor must be flat. So I contour cut pieces of ~3/8" plywood around each floor bump:
To
access the underside of the van floor, the exhaust and a couple of heat
shields were first removed, and the tank had to be dropped down (not
shown):
Bolted floor:
Each rail is secured with 10 stainless steel bolts, in the following stack order:
- SS bolt
- Al rail
- Leveling wood base where needed
- Van steel floor
- Rubber sheet
- 4x4" pressure-spreading Al plate
- Rubber sealed washer
- SS stop nut
The rubber layers are vital to slow down the galvanic corrosion rate between the aluminum and the stainless steel, as the outside is exposed to aggressive chemicals.
Also, note the 6 blocks, from left to right just below the center line of the picture above. These are bump stops made
out of solid Al, secured through the rail walls via 2 M8 bolts. Each
tray will bump into 2 of them. In a frontal crash, their role is to prevent the heavy battery trays to move toward the cabin, by transfering the inertia forces to the rails and their floor bolts (20 per tray bay).
Finally, a water dam was installed at the front to prevent any water spill that finds its way under the floor from spreading to the cabin floor:
The L bar was caulked down and its edges sealed against the pillars. On the passenger side that leaves an opening for the water to flow out,
above the step (bottom right of the pic). Water will also be able to
flow out at the back. All sides of the floor and penetrations were
sealed.
Floor structure done ! Next will be installing the subfloor panels.
____________________________________
>>> next post: Subfloor
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