bgordon's 5 week cardboard & fiberglass build

[bgordon]

Hi all,

Well, it's been some time since my last post. Now I have something to post about.

Our family planned a touring holiday of about 3200km (2000 miles), and I did not want to pull my big caravan along for such a long journey. I also did not feel like sleeping in a tent. My problem was that I have been working for a long time on a folding trailer, but it is MUCH harder to do something like this than a teardrop, and I was not even close to completion. I had to make another plan.

One evening I thought about this site again (http://microship.com/resources/cardboard-core-composites.html) where the builder used cardboard and fiberglass. I looked at the options, and estimated that I could build a trailer in about five weeks (part time). The holiday season was approaching fast, and I had about five weeks before we had to depart. Ouch!

Well, my wife looked at the cardboard trailer design, and gave me the thumbs up (I think she was just desperate to go on a camping holiday again).

And so started my five week mad rush. It really went hectic, and I did not have time to take good pictures, because sometimes I finished late at night, when taking pictures was not possible anymore.

I bought the frame back in 2007. The plan was to build a small trailer, but for a number of reasons that did not materialize. When I realized the trailer would not be built, I converted the trailer to a flatbed trailer. Photo 01 shows the basic frame back in 2007, and the second photo is of the completed flatbed trailer, about a year later.





Okay, back to 2010. I started out by cutting out all the panels in cardboard, gluing it together, and covered it inside and out with fiberglass.

The cardboard teardrop was so light that my 8 year old daughter would have been able to lift it alone.

I did not weigh the completed fiberglass trailer, but my calculations show that it should be around 100kg (about 220 pounds). The flatbed trailer weighed in at just under 150 kg (330 pounds), so the entire trailer weighs around 250kg (550 pounds).









I lifted the fiberglass shell by myself, and my wife placed big paint tins underneath. Then I lifted the other side and did the same. We then rolled the trailer underneath the shell, and I bolted it to the frame.



The trailer towed like a dream. I could easily cruise at 120km/h (75 miles/hour) [the speed limit in South Africa], and my fuel consumption was WAY better than with my big caravan. I hardly noticed the trailer behind me.

We had a great holiday. We traveled 3233 km in total, of which about 300km was gravel roads.

Here is our Family Adventure Touring Trailer.















A last note - If I had to do it again, I would NOT use the same method. Although the cardboard is rigid enough, it flexes too much to get perfectly flat panels. The body filling and sanding took longer that the actual build. It was, unfortunately, NOT a fun build, as I was working against time. However, I did learn an enormous amount. Hopefully those lessons can go into the next build....

Hope you enjoyed the read!

[Shadow Catcher]

Looks great and has some very interesting implications for design and not building a battle ship. So what would you do differently?

[Cliffmeister2000]

Very nice, Barrie!

How about some details? Dimensions, pictures of the galley, how hard were the doors to do, etc?

edit: Also, how thick was the cardboard you started with?

[bgordon]

Hi,

Shadow Catcher:
Yes, I was amazed at how strong the entire structure became when the fiberglass started curing. Amazing. What would I do differently? Well, for one I would probably use 3mm masonite for the sidewalls. It will be less flexible than the cardboard, and will lessen the use of body filler.

Cliff: Thanks for popping in. It is great to hear from you again. As far as details go - it is pretty standard - 3m (10 feet) length, 1500mm (5 foot) width. The cabin is about 4 foot high (1200mm), and about 1700mm (slightly less) from road to roof. I think the interesting part of the build is that there is not a single spar in the roof. And yet I am astonished at how strong it is.

The galley is pretty boring. I'll try to get a picture or two from my photo album. No drawers, shelves, etc. Just a plain top for everything to stand, and space for the stove. I did not have time for anything in the galley. I did not even have time to install the gas struts (springs)! They are still laying around in my garage!

The doors were pretty easy, seeing that they were wood with a single coating of fiberglass outside. I plan to redo the doors altogether. They are not at all to my liking. The plan is that they will be all fiberglass. Hopefully soon.

And the cardboard - I used brand new sheets of 2.5m x 2.4m double wall cardboard sheets. I bought it at a local box manufacturer. No folds or creases. The cardboard should be in a perfect condition before use. No secondhand cardboard boxes! They are too flimsy.

And for those who did not know (I did not know either, until about two months ago) - Cardboard sheets usually come in three forms. First is Corrugated (smooth on one side and corrugated on the other), second is 'single wall', that is smooth on both sides with a corrugation inside, and thirdly there is 'double wall', that is smooth on both sides, with two corrugations on the inside. The two corrugations are divided by a smooth sheet in between.

I used the 'double wall' cardboard. It is by far the thickest at 6mm. The fiberglass added about a millimeter on each side. All the walls and roof is therefore about 8mm thick (5/16 of an inch, if I am correct).

[CliffinGA]

Barrie very nice trailer and absolutely amazing thinking outside of the box!! If you have more pics of the build we would love to see them especially of how tha roof was put on and the curves were made!!

Cliff

[rrawlings]

Thank you so much for a great idea for some industrial prototyping I need to do. I think I will try the 1" thick honeycomb core cardboard though. 6 Lbs for a 4 x 8 sheet and then glass over that should yield a really light yet strong box. Maybe after I try my had at our stuff here at work I will try a trailer with the method

[tk]

Great job! How about some details on the fiberglass. What kind of glass did you use--cloth, mat, chop? What weight? What kind of resin? Thanks.

Best,
Tom

[glassice]

look great how are you going to seal the fiberglass from the water in the air? Back in the 80s there was a wave of this the state of Calif made I beams for low cost housing they got wet from the air , they where tore down. I don"t know how wet it get there but the glass will hold up if you get rot
On a few fixes we dig out the rot cardboard add can foam and reglass from the in side

[jackdaw]

Brilliant

I love the diversity of build materials being used

One of the Brits is building teardrops using corrigated plastic boards for the ultra light build.

Here's his blog http://tearsbeforebed.blogspot.com/

[Miriam C.]

Oh My! Your teardrop is really Beautiful! Amazing construction too. I need to do that and pull with my Nissan..... Never done fiberglass though.

[mikeschn]

Awsome build. Awsome design too! If you can do that good with cardboard, I can't wait to see you build the real thing!

Mike...

[Shadow Catcher]

I have a Kevlar racing canoe that used only a Kevlar honey comb for the bottom portion support and flotation. The idea of an ultralight very aerodynamic rust proof rot proof teardrop with amenities.
There are various composites available and of course what ever honey comb materiel you could wish http://www.plascore.com/product-honeycomb-cores.htm
Or look at the Marine PDF for inspiration http://www.plascore.com/pdf/Plascore_Marine.pdf

I really like the cardboard version and if the fibers are fairly soaked with resin it will take on the characteristics of and strength of a some what linear honeycomb and I Love adaptive use.

[Jim55]

I saw some details of this camper a while ago. (Barrie is my brother). It is VERY well made and I think that the cardbord core sandwich between layers of fibre will never get wet or give any problems. Barrie towed it for over 2000 miles on very rugget roads aind it withstood the test.

Well done!

Jim

[bgordon]

Hi all,

CliffinGA: I'm sorry for not having pictures of the roof construction. It's pretty simple though. A hot glue gun and plenty of patience for the glue to set while you hold it in place!

rrawlings: You guys in the first world countries have amazing products. I have never even heard of that honeycomb cardboard!

tk: Thanks for the compliment! You have to remember I built this thing in South Africa. If you want fiberglass you have to go to a specialty shop. Nothing like those stores in the states (Lowes??). Anyway, I used very old technology: chopped strand, and polyester resin. Just like this website. http://www.rqriley.com/frp-foam.htm I did not use a surform file, because we don't get them here. I simply used a grinder with an ordinary sanding disk (initially anyway), because it was available.

The hardest part of this build was sanding, and sanding, and sanding. I'll say it again, because I also missed it in the planning phase: the sanding alone takes just as long as the entire build prior to sanding. In one of the photos above you can see me covered in dust. At that stage I was washing the trailer after sanding it for a long time. I was just so relieved to not wear the respirator anymore, that I had enough strength to smile for the photo. My poor children were forbidden to come close to the garage during the sanding stage, and I think the neighbours were fed up with me for sending all that penetrating dust their way!

glassice: South Africa is a pretty dry country, so I don't think that will be a problem. If the cardboard should collapse, it wont be a problem, because the fiberglass gives the strength. The only purpose that the cardboard had, was to stay in place while the fiberglass cured. It serves no structural purpose now, but is great in that it is a good insulator (for those cold nights). [I think it will be a bad idea to use cardboard for any structural purpose, like the I-beams you referred to]. And I used automotive paint, which I think should seal the fiberglass enough for my purposes.

jackdaw, Miriam, mikeschn: Thanks for the compliment.

Shadow Catcher: you guys have amazing products in the states. You all should be thankful for living there!

Jim55: Thanks brother. I often wish that you emigrated only later on in my life. I could have learned so much from you! Thanks for your inspiration and wisdom!

[bgordon]

Hi,

The two Cliff's asked for more pictures. Unfortunately they are a bit scarce (due to my time constraints), but here are a few.





The two photos above show the fiberglass inside, but uncovered cardboard outside.



Look at the warped sidewall (above). Ouch! Luckilly that got straightened out real good when the roof came on. I was even amazed myself!

You can also see in the picture above that I am paranoid about fiberglass and safety, especially around children. My daughter wanted to remove some dust, but I agreed only if she wore the respirator.



Photo above: old school technology: chop strand and polyester resin.



This photo is for Cliff (Meister). The hatch, complete with missing gas struts! (that was in the plan, but the time did not allow it).

Fortunately the hatch is so light that my daughters can lift it (to my wife and my surprise).