Best Coroplast thickness for a small car undertray?

[Otto]

What's the consensus view?

[freebeard]

Useful for mockups and testing, not the long haul. If you do use it here's a[n untested] suggestion for shaping and edging it with wire reinforcement.



Shallow notch for taped edge, deeper to wrap the edge, Wires through the corrugations to hold curved shapes.

[Piotrsko]

And: stiffer along corrugations, bendier with corrugations 90 degrees to bending force. freebeards post shows the need for reinforcing in the bendier mode

[Otto]

So, how thick should the Coroplast be for stiffness in an undertray?

4mm? 6mm? 8mm? 100mm? What?

[j-c-c]

I think the deciding factor here is what DF is likely to be created. In racing it is the goal, and not a full negative result (pun intended) here I suspect combined with how the panel is supported and what the mounting spans/frequency is, and what effect any ambient heat (exhaust, etc) will have on the panel to weaken it.
Some flexibility might be a plus in helping have a favorable outcome with the occasional road debris.
My application I'm seeking DF first then drag reduction, I'm leaning towards 8mm CF/kelvar honeycomb custom fitted/shaped w/HT epoxy.

[freebeard]

So, how thick should the Coroplast be for stiffness in an undertray?

Whatever is free, it's only for mockups.

I'm leaning towards 8mm CF/kelvar honeycomb custom fitted/shaped w/HT epoxy.

Maybe for complex shapes like a diffusser. For flats or simple curves, Polymetal/Alumapanel composite.

[COcyclist]

Originally Posted by Otto

So, how thick should the Coroplast be for stiffness in an undertray?

4mm? 6mm? 8mm? 100mm? What?

FWIW I have been using a free used political sign for my belly pan for over a decade. It measures 3/16" or 5mm. it is more reinforced than the photos in my album show but other than that is is holding up fine. My car is a diesel so the exhaust is fairly cool. I covered the whole bottom of the car from just behind the catalytic converter.

[Phase]

200mm. itll keep all air from going under the car

[aerohead]

Years ago, I thought it was generally agreed that, the 10mm Coroplast, from The Home Depot had turned out to be more than adequate for belly pans.
It's a thermoplastic, and will 'yield' at some temperature threshold, but exhaust components can be insulated, or heat-shields fabricated to mitigate heat effects.
Sag testing will reveal necessary center-to-center support spacing.
And hat-section stiffeners can be attached wherever deemed beneficial.
Consider 'sections' of pan, which can readily be removed for inspection.