Coroplast - supporting bracing for "Aero Tail" on my trailer
 

(Read a LOT of posts about coroplast, especially the RV with the boat tail...)

How much BRACING is required to support these 4'x8'x.156" coroplast tails behind my 6'tall x 8'wide enclosed snowmobile trailer?

Should I run just a 1"x1" aluminum angle, in the two upper corners? (Indicated in RED in photo).

And 2 more angle-aluminum in the lower corner (edge) also?

Do I need more structure, as in creating a "picture frame" of the 4 corners, and tying them all together... (pictured in BLUE)?

There's probably going to be a lot of buffeting, and coroplast isn't as heavy duty as the ones the big rigs use. I'd go with the picture frame.

Edge support is nice, but I believe you would be better off anchor supporting the centers since it would reduce flex and stress

Do you have the Coroplast yet?

What are those stringy white things in the fourth picture?

Have NOT purchased anything (yet).
The frame design was from the RV thread... I was thinking of just doing the 4 corners, and picture-fame (tying 4 sides together at center).
https://ecomodder.com/forum/showthre...d-e-18151.html

Cool. Coroplast is not fit for purpose. It's fine for mockups and experimentation, but the final material should be Polymetal or equivalent (Alumapanel, Grimco Maxmetal).
https://ecomodder.com/forum/member-f...1-100-0866.jpg
It cost more than plywood but is 1/10th the weight. The samples shown were sheared, rolled and braked by hand.

It is pre-finished and would match the build quality of your trailer.
Polymetal has sufficient shear strength, you could make it a monocoque box. With Cardboard Aided Design or Coroplast, you'd want a frame that is triangulated.
http://hiataircraft.com.ua/wp-conten...14/06/fuse.jpg
http://hiataircraft.com.ua/wp-conten...14/06/fuse.jpg

The forces on the tail are FAR greater than coroplast can handle.

There are about three designs of trailer tails on big trucks. Take some pics at a truckstop. Open and closed.

See the STEMCO site. That fully boxed version is great for FE. But in a heavy crosswind it’s leveraging the trailer wheels off the ground. The driver doesn’t have his trailer tandems as far back as allowed, he’s in trouble.

https://www.farmtek.com/wcsstore/Eng...ge/104471b.jpg
4x8sheet $69.30usd and a little more durable final skin

8mm Twin-Wall Polycarbonate Sheet - 47.25"W x 96"L

Support required depends on pressure balance and forces involved
The one being a picture called a picture frame I see as a bird cage support structure you would either bend the colorplast over the framing or cut panels to fit between the frame sections like gussets.


Pressure balance as mentioned is critical to dealing with off angle wind or side wind. Couple of days ago driving South through Idaho in a ground blizzard even pressure balance was very important the front tires would actually slip a little as they hit the ice first giving me time to respond with the drive tires

Better than Coroplast but it's still brittle. I have canopy/bridge between my Airstream and carport made of the stuff.

It's less flexible than Coroplast.

10mm it's what I used to create the internal structure of my nose cone using a heat gun I was able to bend it into oval shape. Extremely Ridgid Id say 60lbs centered on a 3 'span perpendicular to the web=1/2" deflection , using an 8' pice for a temporary shelf

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As for spacing of support it depends on if the support is with the perpendicular web or acrossed it.

Polycarb is anything but brittle:

https://youtu.be/FSP-2VINGa4?t=141

Unless it's degraded from age, which applies to any polymer.

Sorry I'm late to the party here, but I've used a lot of Coroplast. Big flat panels are problematic, but if you can use a conic section, with maybe 30 degrees of arc across the width, it stiffens right up. For a flat section, you might make a series of bends to give a shiplap effect. You can also stiffen it with more layers, or by ordering the thick stuff. Non-paintable silicon seal is a good adhesive. I have also bent it into hat sections to add ribs, and used strips of unidirectional fiberglass for hard points. For a monocoque section, just adding extra layers near the mounting points helps a lot.
I'd always start by trying for a monocoque, and reinforcing that, rather than building a frame and wasting most of both it and the covering. The peak loads are gusts, and a bit of calculated flex can handle that with far less material. However, if you don't melt the ends of the flutes to seal them, you will hear people calling it cardboard.

Even later to the party...
What about these panels?
https://www.homedepot.com/p/FiberCor...C320/206084818
https://images.thdstatic.com/product...320-64_400.jpg

The FRP is a layer of glass fiber particles in a plastic matrix layered onto an unspecified plastic corrugated core.

Could be a fancy Coroplast, it could be more brittle like greenhouse glazing.

Maybe you could inspect it at your local Home Depot.

If that stuff was for structure, not decor, it would have 'glass on both sides, and preferably continuous, straight fibers. Back before the beancounters ruined Boeing, their surplus shop used to have a marvellous variety of honeycomb-core structural panels of various weights, down to near-Coroplast and beyond 3/4" plywood. Making your own sandwich panels with foam, epoxy, and 'glass cloth is not all that darn difficult, and you get to do curves and whatnot.

AND coroplast comes in many other thicknesses, up to 1" thick which will support a person stepping on it. Hard to find and expen$$ive, but it's out there.

In my area, it is a special order item at $101.00 per 4'x8' sheet and a 10 day lead time.
Here is the link on product info from the mfg.: https://www.nudo.com/resources/p6_product_data.pdf

I have used the thin sheet version of this product: https://www.homedepot.com/p/Glasline...9600/100389836 for an undertray, but in that application the edges were all supported by existing car structure, did not extend very far to the rear and worked very well. My latest project does not offer that same support and I don't want a whole bunch of bracketry so I'm looking for a more rigid panel.

Nudo are who make Polymetal, which would be my preference. They have a product that is a compromise between the two, aluminum skin on polypropylene corrugations.

www.nudo.com/p_alumacorr.php?crumb=%3Ca+href%3D%27l_sign_panels .php%3Fitem%3Dproduct%27%3ESign+Panels

The advantage (to me) of the aluminum skin is that it comes prefinished with baked enamel. I see they have a new product called ValuMetal, similar to Polymetal without the fire rating in white only.

www.nudo.com/p_valumetal.php?crumb=%3Ca+href%3D%27l_sign_panels .php%3Fitem%3Dproduct%27%3ESign+Panel

Whichever be sure to seal the ends of the corrugations shut before it hits the road.

I don't want to be responsible for a new thread so I'll drop this here. I've only watched this one episode:

Reverse trike with fluted plastic body (part 13)

I'd have done a different frame design for ingress/egress, but he does get a tight radius across the corrugations of everybody [else]'s favorite material.

he can make it STRONGER by adding a few coats of bed liner to it....




:D


the engineering problem have been solved

Sometimes, we need stiffness more than toughness. I'd much rather see a full set of numbers on this stuff.

line-x bed liner

That's not the numbers he asked for.

No comment on the Coroplast piece in the video I posted that was curved across the corrugations?

He did that by heating the inside with a heat gun where he wanted the bend.

There ya go. Heat gun > bed liner. And cheaper, too.

Anybody actually analyze the failures for their cause? Like web failure or skin buckling, or skin seperation??? Bedliner will stiffen the skin, but if the failure is the web, or skin between the webs, it wouldn't help. I myself shove music wire into the holes every so often to make it linearly stronger but that does nothing to preventing collapse parallel to the webs.

Just to follow up, I did end up using the Corrugated FRP Wall Panel to make my front undertray. It is quite strong and I'm happy with the result.
It's pretty light and strong. This is a 4' long level and a full 5qt oil jug.

https://lh3.googleusercontent.com/pw...-no?authuser=0

https://lh3.googleusercontent.com/pw...-no?authuser=0