Has anyone done fiberglass over foam trailer?

[walking eagle]

I guess I don't understand the concern for strength.

1. As far as the base, it's all going to have a metal frame work that the foam pannels are placed into, then fiberglassed over the whole thing. Inside too as I explained earlier.

2. http://www.youtube.com/watch?v=7eUt0YnNF3o&feature=related

3. Because the moment of intertia is increased so much by having the foam in the center is is stronger than it just being fiberglass. That means it's stronger, pound for pound than a Casita, or a Wilderness flip-pac, or a normal truck topper, or a tentrax

http://www.tentrax.com/OffRoadAT_Trailer.html?gclid=CKiMj9yDh6ACFRMNDQod21UU1A

4. It's stonger, pound for pound, than skining it in metal - aluminum or steel.

So, I could take the whole frame (all the grey), and then put sheet steel on it, say, 24 guage. The sheet steel is adding very little to the structural integrety of the whole trailer. If I tied it down at three corners and put a weight at the 4th corner, the twist or deflection that could be measured at that forth corner would change very little with the sheet attached or not. Now, if you did the same thing with the foam and fiberglass, glass it up to make the weight equivalent, and that 4th corner will twist / drop much less.

Why is that important to me? I don't want to make the frame out of any heavier material than I have to. If it's all one unit construction, I can make it weigh less. I don't intend on packing 1,000 lbs of ammo into the trailer, so I don't need it built like a military trailer. Heaviest part of the whole thing will likely be the 37" Hummer tires....

Oh, and notice, the frame has metal in certain area's I would consider to be high potential of impact areas.

Now, on the finish, that would take a ship load of work from what I've seen and done, to get it paintable. Fortunately, I'm not at all above coating the whole thing with Durabak!

I'm picking up some foam tonight for a smaller project - as in smaller than a shoe box. We'll see how that goes. Figgure I'll start small, like what I did in college, and then step up to something inbetween (thinking pods on either side of drawer system in my 80), then the trailer. Then if that turns out, then maybe I'll think about a camper pod or pop-up on the top.

 

[ntsqd]

The design challenge in all foam/composite construction is distributing the loads. Build-in a point loading and watch it come apart in use.

 

[Bogo]

As for epoxy, call West Systems, explain what you are doing and ask for a recommended epoxy. They may much, much more than the standard 105/205 system. You need a resin that is extremely durable and can handle insane vibration. 105/205 is strong but brittle, probably not the best combo for an off-road trailer. Some variation of ProSet may be better.

For vibration, forget fiberglass. Use kevlar cloth instead. Due to the metal framing, choose an epoxy that doesn't shrink, but that may be at odds with handling vibration. If that is the case, then make the panels and size the metal to suit. Note you will need to protect the kevlar cloth from UV light, and the epoxy from water intrusion.

Yes, you will need to avoid point loads and all mounting places will need to be built up thicker to distribute the point load over a wide area.

I explored doing a fiberglass shell for my Micro RV project, which is currently stalled due to funds, and eventually figured out composite panels was the way to go for simplicity, ease of construction, and durability in the face of hard knocks. Make the frame so all faces where panels will be mounted are coplanar. Place a lip that the panel can be glued to, and glue the panel in place. Look up "VHB Tape" and "auto body glue". When using them cleanliness and proper surface preparation is mandatory, but the results can be as strong as welding. On top of that the structure can be light and stiff while providing insulation. I decided making my own composite panels is the way to go for me after not locating suitable ones available in small volumes. I'll be using AL sheet on each side of a foam core. Depending on where the panel will be used will determine the thickness of the skins. An example is the bed floor inside surface will have .1" AL diamond plate while it's outside surface will be .0625". The ceiling panel will have .032" skins on both the inside and outside. I did locate some fiberglass and carbon fiber skins but haven't decided if the added cost is worth the weight savings. I keep making changes to my design, but they are mainly small details now.

Take a look at this camper: http://www.expeditionportal.com/forum/showthread.php?t=20822
and here also: http://forum.ih8mud.com/expedition-builds/245430-travelling-cruisers.html
Notice how the framing is done.

Some construction techniques in this thread: http://www.expeditionportal.com/forum/showthread.php?t=17675


I have a corner design detail for what I plan to do in this thread:
http://www.expeditionportal.com/forum/showthread.php?t=32301
For the lower corners that can get hit by rocks it isn't much different than the outside corner shown. I'll just be using thicker AL plate and skins and a smaller radius for the curved outside piece. What is shown is for the popup top.

 

[UK4X4]

I think the only benefit of fiber over foam construction is sexy curves.

Other than that if you can live with straight lines then a steel or aluminum frame with panels is simple lightweight and proven construction.

Panels can be most any material , if you not living in it...insulated is a waste of time.

Wood with a fiberglass cap is a strong light method with 1 dimensional curves easily possible, even with 3mm plywood the fiberglass adds a huge ammount of strength and waterproofing.

To get from rough fiber to a gel coat finish is time comsuming,

I made wooden formed bath and shower enclosure, stained it and then used a two coat resin coating for easy cleanup...

7 years on the resin is good, but marked, so I just tiled over it on my last trip home.

steel box section frame riveted and glued aluminum panels, built to dismantle into three sections.....so i ship as a dog kennel !

 

[walking eagle]

I think the only benefit of fiber over foam construction is sexy curves.

and the light weight, and structural rigidity, ect. as above.

Other than that if you can live with straight lines then a steel or aluminum frame with panels is simple lightweight and proven construction.

Fiberglass over foam is also simple, lightweight (lighter), and proven construction. Hundreds of airplanes (scale and fullsize), and autos, and boats, ect. make it a proven construction.

Panels can be most any material , if you not living in it...insulated is a waste of time.

A top sleeping capsule, or perhaps pop up might be added at some date. Which would be constructed of the fiberglass over foam. And be more complicated - thus the idea of starting with the simple bottom and advancing as skill advances.

Wood with a fiberglass cap is a strong light method with 1 dimensional curves easily possible, even with 3mm plywood the fiberglass adds a huge ammount of strength and waterproofing.

And the advantage of this over foam?

To get from rough fiber to a gel coat finish is time comsuming.

Which is a perfect reaseon not to gel coat it, or paint it, but Durabak it - as I said earlier.

steel box section frame riveted and glued aluminum panels, built to dismantle into three sections.....so i ship as a dog kennel !

Nice looking trailer - though for example, I'm guessing your door/shelf is made from 1x1x.065" square tube. Estimating 1.5' x 4.5' (scaling off rim size) Two cross braces - that's 15 ft. of tubing @ .827 lbs/ft. = 12.40lbs Add in 6.75 sq ft of 14 guage diamond plate - You're at 37.7 lbs. Now do the same thing with foam and fiberglass, make the frame out of angle steel 1x1x.065" same 15ft, but now .4125 lbs/ ft for 6.18lbs. So just in the frame the weight is 1/2. Put what, 2 lbs of foam in?, 2 layers of 10 oz fabric, 2 layers 4 oz http://www.fibreglast.com/fibreglast_materials_calculator that's more than needed and just under 7 lbs Round 15 lbs? Vs. nearly 38lbs? 40% of the weight - that's quite a bit when you start adding up all the panels on a trailer. Even if I'm off by 50%, and it's only a 20% weight savings, on a 1,000 lb trailer, that gives you 200lbs of extra cargo capacity. If the 40% is accurate, well, you get the idea......


I'm not trying to convert anyone here, just looking to see if anyone else has done this method for a trailer - airplane, and car are pretty easy to find examples of. There are valid reasons to choose it over skinned steel. I think most people are intimidated by their lack of familiarity in the process and the mess. Skinned steel has the advantage that more people are familiar with it. There are solid reasons to use fiberglass, like on the tentrax, and fiberglass over foam can be every bit as strong, and stronger, and is doable on a one off basis, where you would never do a mold just for a single trailer - too cost prohibative.

 

[opp1]

i don' t think it can be done. Just like that lie all polyester will eat Home Depot foam. Treating serious issues with deliberately inappropriate humor. fiberglass trailtop component kit and a fiberglass structural panels .Two different style of builds

 

[Chasingopenspaces]

When the roof started leaking on my old northstar pop top slide in, i did something similar to this but with thin 1/4?sandwiched plywood. Figured it would be a lot lighter and more durable than any other method I had available. I used a plywood frame because I felt I needed a material that would hold screws/bolts and couldn’t think of a way to do that with just foam, but there must be some way to do that. I insulated it with foam from Home Depot and for what it’s worth this roof it held up really well and didn’t have any signs of wear when I sold the camper 3 years later. I had built a kayak with this method and was really impressed with the strength…

 

[calicamper]

Mike Petey likes to use clear box tape over his forms. He holds the fastest prop driven plane record and his current fun project is a ebike transport bush plane. His stuff is “the standard” and he loves forming parts using clear box tape.

For a box just using 1/4 marine ply with glass over it for weather proofing is perfectly fine.

foam / glass panels can be bought by the panel if you want to spend $. Resin and glass aren’t cheap.

 

[TwinStick]

If it works for this, it should work for you. As others have said, if you need more strength, use kevlar layers or more fiberglass layers.