ultra lightweight floating popup camper

[wlivesey]

bump

[BaerClaw]

nice i put off my build to watch yours! so glad your getting stuff done again. hahaha

I really like your ideas

[coal_burner]

Bub has finally gone camping, and i've learned several things. Bub tows nicely at 85 MPH. At 90 MPH, there was a little bit of buffeting so i slowed down and drove the rest of the 150 mile trip between 75 and 80 MPH.
I have been averaging about 46 MPG in my car per 600 mile fillup. The tank that my 300 miles of round trip bub towing averaged a little over 42 MPG. I think that having a smooth bottom really helped avoid stability robbing and MPG robbing turbulence under the trailer.
I replaced my aluminum tongue with a 2 x 2 x 1/8" steel one and used angle brackets bolted onto the deck to allow me to have a removeable tongue that gets secured with a bolt that slides through the side. This weighs about 20 LBS more than the original tongue.
To get BUB's tongue weight down to 90 LBS, i bolted one of my 80 LB boat batteries to the deck as far back as i could manage(i think the max tongue weight on my hitch is about 130 lbs).


I used muscle power to lift the cap for setup and then deck screwed 4 scrap pieces of 2 x 4 into place to keep it that way. Since i never got around to making a door, i C-clamped a piece of 1/4" plywood in place for a bottom half and a small tarp in place for a top door half.
I had 220 volt near where BUB was parked(no neutral wire so no 110v) so i spliced 2 space heaters in series to heat bub overnight. They amped out at about 1500 watts total and that was way way way way too much. The outdoor temperature was in the high 20s. I opened up about 1 square foot of my door tarp and Bub still got over 90 degrees F during the night. So i opened up the tarp to about 2 square feet open and aimed one of the heaters straight outside. Bub then maintained a just bearable 80 degrees.
It drizzled for just about the entire first night i was there, and the one thing that i thought could never occur, occurred. BUB leaked. Nothing major, just 3 spots along roof seams that dripped once every 5 minutes or so. When i inspected things the next morning, I found that where the fiberglass was laid over the foam seams, a small amount of epoxy would flow out of the cloth and into the foam seam. This left me with a couple dozen pinholes in the roof at the seams. When i gel coat the roof the pinholes will be filled in, but until then, duct tape along my roof seams worked fine.

On the opening day of deer season, i woke up at 7 AM. I had my folding directors chair set up in bubs changing area, coffee poured, and rifle pointed out BUB's back window by 7:10. I saw my first deer at 7:15, took a 235 yard shot with an AR-15 and had my venison for this year (damn i'm good).

There wasn't much room for my feet inside the camper, so i'm going to design a bowed out rear door attachment that will give me more room (just in case i spend more than 5 minutes sitting there next year).
I'm also thinking of cutting a 2 foot diameter hole in the middle of bub so i can use it for an ice fishing shanty.
Sorry there are no photos but the lack of cell phone coverage caused my battery to die so i had no picture taking device on hand.
weekend spent with rifle in hand. No beer drank.

[devigata]

I'm also thinking of cutting a 2 foot diameter hole in the middle of bub so i can use it for an ice fishing shanty.
No beer drank.

Uhh, wouldn't a hole in the floor cause it to sink?

Hole in the floor... could that be the fire-pit?

[brian_bp]

This is a fascinating project, and I'm glad to hear it is working so well.

Bub has finally gone camping...

On the opening day of deer season, i woke up at 7 AM. I had my folding directors chair set up in bubs changing area, coffee poured, and rifle pointed out BUB's back window by 7:10. I saw my first deer at 7:15, took a 235 yard shot with an AR-15 and had my venison for this year (damn i'm good).

Man, that was a lot of trailer-building work for a five-minute event!

weekend spent with rifle in hand. No beer drank.

[bve]

As others have stated this is a very cool build indeed.

I'm curious about the overall structure, I've never worked with fiberglass but I'm really interested in the idea, the profile possibilities are very enticing.

If I've followed the build correctly.... aside from the window frames, and the sealing strips for the top and bottom shells the entire 'body' is foam and glass - is that correct?

How many layers of fiberglass where used?

[coal_burner]

Uhh, wouldn't a hole in the floor cause it to sink?

nope. the floor itself is buoyant.

Man, that was a lot of trailer-building work for a five-minute event!

Hmmm..... next time i'll have to miss a couple of times before making a good shot.

As others have stated this is a very cool build indeed.

I'm curious about the overall structure, I've never worked with fiberglass but I'm really interested in the idea, the profile possibilities are very enticing.

If I've followed the build correctly.... aside from the window frames, and the sealing strips for the top and bottom shells the entire 'body' is foam and glass - is that correct?

How many layers of fiberglass where used?

along with the window frames and seal strips, my floor has some 1 x 4 wooden framing and 1/4" plywood under the fiberglass in the floor. Next build, i won't be using any structural wood like that at all. The underside of BUB, which has nothing but 3 layers of fiberglass over foam, feels just as rigid as the top side, which has 3 layers of fiberglass over 1/4" plywood.

The deck and walls have 3 layers of 'glass on each side (one layer laid diagonally on the deck). the top edges of the walls have 5 layers on each side (for rigidity). The entire canopy, roof and all have only 2 layers on each side. Inside the wheel wells, i think that i put 4 layers on.
Strength wise, i would have been good with 2 layers of 'glass everywhere, but things probably would have bent and bowed a little if someone were to lean on BUB, so the extra layers are all about preventing that.

[ktm_2000]

In the past I built a 4'x6' fuel tank covering hatch out of corecell and a couple of other pieces out of divinicell for my boat so I'm familiar with glassing techniques and composite construction. When I became interested in a TTT I thought of building a composite camper but didn't want to spend the $$$$$ on the core matierials because of the volume required. The insulation boards are less than 1/10th the cost of corecell and could easily make up for the difference in cost of using epoxy over polyester resin.

I'm a newbie here and am inpressed by the method you used. I'm curious which brand of foam insulation you used as well as if you did some testing to figure out which types don't dissolve from epoxy. If you did testing, did you consider polyester resin to reduce costs? if so did all the different types dissolve from the resin?

What type of glass did you use? I can't really tell from the pics but it seems that you didn't glass the inside, is the product balanced? ie as strong pressing from the outside as from the inside? When researching the build for my fuel tank hatch, I was given the advice to put 2 layers of glass on the top and 3 layers on the bottom and the product would be strong because the 3 layers on the bottom are where the strength is needed yet the top only needs enough glass to protect the foam from being crushed.

[angib]

When researching the build for my fuel tank hatch, I was given the advice to put 2 layers of glass on the top and 3 layers on the bottom and the product would be strong because the 3 layers on the bottom are where the strength is needed yet the top only needs enough glass to protect the foam from being crushed.

Poor advice, I would say - I have just been discussing this very question with a race boat builder and the European standard on boat strength suggests that the inner skin should be no less than 70% of the outer skin weight/thickness. I would expect the outer skin to be thicker as it needs to be resistant to 'punctures', which the inner skin doesn't.

Andrew

[ktm_2000]

I don't know who's right but here is the thought process which I was given by a reputable boat builder, not me which I thought was sound and followed successfully.

Fiberglass works well when used in tension

In the case of a deck hatch which may have substantial loads placed upon it from 1 direction. Load is directed down upon a hatch the glass which is on top of the core is being compressed due to the load and the material which is under the core is being stretched. Beefing up the glass on the bottom increases the products resistance to stretching and thus creates a product which doesn't deflect much.

How I implemented the idea:
I built the hatch by prepping my glassing table with PVA and shooting 3 layers of gel coat in 15 min intervals then waiting 45 min and laying down a layer of 1.5oz mat. The Mat was then followed by 2 layers of 1708 biax cloth and was finished by mixing up some cabosil and trowling it on the area where the core was to go. After the putty was on the core was placed in positon and everything was covered by a sheet of plastic and the core was weighted down. I covered the whole thing with sleeping bags and more plastic and a electric heater was placed under the whole thing to run overnight.

The next day I cleaned everything with acetone layed on 3 layers of 1708 with the last piece being set in poly resin with wax. I then covered it all and with the plastic and sleeping bags and let it go for 2 days with the heater on.

The part came out beatifully for my inexperience and I have had it in place for 3 years. I have had quite a few people on board as well as taken the boat out in rough seas and the hatch is not bouncy at all.

[brian_bp]

...

Fiberglass works well when used in tension

In the case of a deck hatch which may have substantial loads placed upon it from 1 direction. Load is directed down upon a hatch the glass which is on top of the core is being compressed due to the load and the material which is under the core is being stretched. Beefing up the glass on the bottom increases the products resistance to stretching and thus creates a product which doesn't deflect much...

Sure, but the top and bottom skins of fiberglass are like the top and bottom flanges of an I-beam: the bottom is indeed in horizontal tension, and the top in horizontal compression, and it's the combination of the two which provides bending strength. Unless the fiberglass is better in compression than tension, the top needs to be comparable in thickness to the bottom for optimal strength; in the extreme, if you depend entirely on the bottom skin it acts like a hammock and must deflect a lot to provide any vertical support, regardless of its strength. The core is mostly there to keep the skins a constant distance apart, like the web of the I-beam.

[ktm_2000]

Here's the guy I got my advice from.... he does a better job than I did explaining the whole thing.

http://bertram31.com/proj/tips/core.htm

onto the point to all this discussion, I think that the guy who put together his trailer has an interesting concept for building and I'm wondering what the ideal build proceedure should be???

I was thinking of building my side walls by gluing pieces of insulation to make one large panel. From there a router could be used to create a slot to run a pvc tube for a wire chase. When ready the outside could be laminiated with 1 layer of 1708. In a second glassing session the inside could receive a layer of 1708 with the mat side down on the insulation, a second layer of 1.5oz mat could then be added on the inside and be put on quite wet and 1/4" birch ply could be added for a pleasing interior. Once the panel was cured it could be cut to whatever size/shape you wanted. I have no idea how the pink insulation bends but it could probably be helped out with a heat gun and one could come up with some interesting shapes and unusual design ideas.

As for the top, it would be a lot more difficult to glass each side and I'm still trying to figure out how I'd do it but for now I'm thinking of connecting the pieces with 1/4" birch ply then adding the insulation on the outside radiusing the corners then glassing 2 layers of 1708 on the top with the first layer covering over the side quite a bit. The whole thing could then be faired to fill in the weave and then shot with one of the high build primers to create a pretty smooth surface ready for paint.

[angib]

Here's the guy I got my advice from.... he does a better job than I did explaining the whole thing.

Sorry - he's writing utter crap. He may well know about laminating but he understands nothing about structures. The idea that one can choose how much tension or compression you get by varying the skin thicknesses is laughable.

The problem with using sandwich construction for teardrops always comes back to the amount of work to get a good surface finish and the difficulty of making the corner joints. It can all be done, but it usually involves enough cost and time that the benefits don't justify it.

Andrew

[Arne]

The tension flange acts like the string in an archer's bow and the maximum force that can be developed is limited only by the yield stress of the flange material.

The compression flange acts like a strut and is susceptible to buckling before yield stress can be developed.

meaning, the compression side (top) will fail before the tension side (bottom).

[coal_burner]

I'm a newbie here and am inpressed by the method you used. I'm curious which brand of foam insulation you used as well as if you did some testing to figure out which types don't dissolve from epoxy. If you did testing, did you consider polyester resin to reduce costs? if so did all the different types dissolve from the resin?

I used owens corning foamular 150 extruded polystyrene insulation (the standard cheap pink stuff that home depot sells). I did some tests on it using 3 or 4 different types of epoxy, bought from the local hobby shop. Since Aircraft Spruce Co. sells polystyrene for aircraft composite use, i figured that it's probably good enough for a non life or death application like a camper.
Aircraft spruce had warnings not to use polyester resin with polystyrene without using a special foam sealer. In order to avoid that hassle and because epoxy is stronger than polyester, i just went with the more expensive stuff. If things didn't work out, i didn't want to say "if only i had used...."

What type of glass did you use? I can't really tell from the pics but it seems that you didn't glass the inside, is the product balanced? ie as strong pressing from the outside as from the inside? When researching the build for my fuel tank hatch, I was given the advice to put 2 layers of glass on the top and 3 layers on the bottom and the product would be strong because the 3 layers on the bottom are where the strength is needed yet the top only needs enough glass to protect the foam from being crushed.

if my memory serves me correctly, i used 5.85 Oz/Yd e-glass cloth (#7533 from aircraft spruce). Right now, most of the inside of the cap is not glassed. This will be rectified when the weather warms up. Everything on the base unit of BUB is glassed, and is needed to be for structural reasons.

There are 2 ways to look at the compression/tension strength issue with composits. One is to view the foam as a spacer with negligible strength (polystyrene), in which case you would need more layers of fiberglass in compression than you have in tension. The other way is to view the foam as lending some strength and rigidity of it's own (divinicell) to the composite.

Having my 14 year old nephew destroy test samples, i noticed that EVERY one of them failed when the compression side delaminated from the foam and buckled. More layers of glass in compression would have given that side more rigidity and prevented the buckling. An experimental aircraft builder at my local EAA chapter showed me a test sample of fiberglass over divinicell, which had broken in tension. The compression side of the sample didn't even have a crease where he had his test weight hung. I think that the strength and rigidity of divinicell may have made the results of the boat builder's method match his expectations, but not for anything like the reasons that he explained in the link.

I was thinking of building my side walls by gluing pieces of insulation to make one large panel. From there a router could be used to create a slot to run a pvc tube for a wire chase. When ready the outside could be laminiated with 1 layer of 1708. In a second glassing session the inside could receive a layer of 1708 with the mat side down on the insulation, a second layer of 1.5oz mat could then be added on the inside and be put on quite wet and 1/4" birch ply could be added for a pleasing interior. Once the panel was cured it could be cut to whatever size/shape you wanted. I have no idea how the pink insulation bends but it could probably be helped out with a heat gun and one could come up with some interesting shapes and unusual design ideas.

I'm considering a traditionally shaped teardrop build next, and that pretty much describes, how i would make the walls. I would cut the walls using a circular saw, and sand everything smooth with a belt sander. Glass is really hard stuff, and would dull even a carbide router bit pretty quickly. The router bit would still be able to cut, but a dull bit creates a lot of heat which the foam would contract away from.(move the belt sander a lot to avoid melting foam with it(learned the hard way)). I've also cut composite panels with a jig saw and sawzall. The reciprocating motion causes things to delaminate.

As for the top, it would be a lot more difficult to glass each side and I'm still trying to figure out how I'd do it but for now I'm thinking of connecting the pieces with 1/4" birch ply then adding the insulation on the outside radiusing the corners then glassing 2 layers of 1708 on the top with the first layer covering over the side quite a bit. The whole thing could then be faired to fill in the weave and then shot with one of the high build primers to create a pretty smooth surface ready for paint.

As for the top, i would keep the heat gun away from it. Polystyrene doesn't really soften very much before it just melts or collapses.
My plan is to set my wall panels in vertical jigs, then bend a 1/2" foam roof panel over the profile, securing it with wet micro and coarse drywall screws. I would then apply another layer of 1/2" foam over the first, connecting them with a layer of wet micro, and more drywall screws. After the micro dries, remove the screws, fill the screw holes, then apply fiberglass. Once the outside is glassed, the whole thing can be stood on end(it's not connected to a floor yet), and the inside of the roof can be glassed while standing semi-vertically.

By the way, 1" foam with 2 layers of fiberglass on each side weighs 8 OZ. per square foot. a 4" thick deck with 4 layers of glass on each side would weigh about 20 OZ. per square foot. Using these numbers, a 4x8 traditional teardrop trailer shell and deck could be made weighing just 95 LBS.

Here is a drawing of the suspension i would propose for a trailer this light.