Ultralight Weekender

[Greg M]

Hi folks, first post on this great forum.

I'm looking at making a 10' version of the weekender and, because my Acura EL has a very low towing capacity, I'm looking to make it as light as possible.

Here's what I'm thinking:

First off, an all aluminum frame of 2" square by .125" wall 6061. Next is the part where I wonder if I'm being crazy. The body will be from 1 1/2" foam with fibreglass skins inside and out. I'll secure the body to the frame by first attaching 1/2" ply to the frame, then adding a 1/2" ply floor to the inside of the body and bolting it together like a fibreglass and foam sandwich.
So, dou you think I'm nuts? Would I be better off just making the body as a bunch of wooden face frames, with styrofoam insulation to give the skin something to adhere to?

Any input (even phone #'s for good shrinks) is appreciated.

-Greg
Victoria B.C.

[WarPony]

Ahhhhhhh, welcome to the forum! A new victim.... oops, friend. If you have the means, talent and source for supplies, by all means, build what you want. Your idea sounds like a lot of work but I can't lay fiberglass so take my comment and throw it out the window.
Dude, just go with what you know and take pictures so all of us can see the progress. Have fun with it!!

[Q]

Sure, it would work. I once built a small row boat out of 1/2" surf board foam with one layer of fiberglass mat and one layer of fiberglass cloth on each side. It was very light, very strong, and took less than a day to build. Don't try to lay up fiberglass on to styrafoam though, it'll melt.

Q

Hi folks, first post on this great forum.

I'm looking at making a 10' version of the weekender and, because my Acura EL has a very low towing capacity, I'm looking to make it as light as possible.

Here's what I'm thinking:

First off, an all aluminum frame of 2" square by .125" wall 6061. Next is the part where I wonder if I'm being crazy. The body will be from 1 1/2" foam with fibreglass skins inside and out. I'll secure the body to the frame by first attaching 1/2" ply to the frame, then adding a 1/2" ply floor to the inside of the body and bolting it together like a fibreglass and foam sandwich.
So, dou you think I'm nuts? Would I be better off just making the body as a bunch of wooden face frames, with styrofoam insulation to give the skin something to adhere to?

Any input (even phone #'s for good shrinks) is appreciated.

-Greg
Victoria B.C.

[angib]

So, dou you think I'm nuts?

Weeeeeell....... pretty much.

You're overdoing it, this isn't a light aircraft. The aluminium frame is overkill (unless you happen to be an aluminum fabricator) - just use 2" x 2" steel angle and it will only weigh 10lb more than the aluminum. More important is to avoid excess frame members - have a look at my Superleggera chassis for some ideas:



The glass/foam sandwich would be beautifully strong, but if the skins are thick enough to be durable, they won't be much lighter than if you used 1/8" ply skins - and the glass would certainly be a lot more work. If you are happy with glassfibre, then build ply/foam sandwich panels and join them together with glass tape. You will still need to put a lot of thought into building framing into the sandwich where you want to attach things like hinges, locks, lights, etc.

Andrew

[mwatters]

I can vouch for the above frame design. I had a trailer with that basic design of frame. It was a '72 PlayPac. Only difference was that the backside had a cross-beam that served as a rear bumper for the trailer. Considering the frame was enough to support a 7x11 fiberglass trailer body - with all the internal gear - for 30+ years... I think it'll clearly be enough for a teardrop.

The other advantage of fiberglass that hasn't been mentioned here yet is that it's very water tight. Just run the glass over all the seams and you don't have to worry about water coming through at the joints (what seems to do in a lot of the older trailers).

I think if it were me - I'd consider a hybrid sandwich, foam in the middle - 1/8" ply on the inside of the trailer and fiberglass on the exterior.

Another option would be foam with 1/8" plywood inside AND out - with the exterior getting just a single thin layer of fiberglass just to seal the wood. The wood provides most of the structural stability, the fiberglass adds the waterproofing. This approach would save a bunch of bucks on fiberglass too.

mkw

[asianflava]

Make sure the cloth you use on the outside is heavy enough. One of the problems with surfboards are "dings" They are built so light that they are easily dinged.

[GeorgeTelford]

Hi All

I think he means buying it as a ready made sandwich, foam core with white Gelcoated GRP either side, he would not be laying anything up at all.

I am awaiting a price back on sheets of this (its made to order only) I want to do a weekender, but using single sheets like original design, but to include insulation, ie retain speed but have the insulation too.

Aluminium Chassis is a bad idea, to get the same strength as steel you need thicker material ergo end result is little if any lighter at all. long term the chassis will crack way before the steel.

[Greg M]

Actually, my original idea was to build the body of foam and then lay up the fibreglass over the entire thing, making it seemless and therefore watertight. What I've started to think about though is to laminate up large sheets and cut out the panels, then use fibreglass tape to join them. If neccessary, I have a 4' x 8' press available to me to aid in making the panels. I wish it was 10' long,but you can't have everything.

George, where are you getting the quote on the material from? Could you let me know what they come back with?

Thanks Andrew and Mike for the suggestion of the super simple steel frame. That would be cheaper and easier for me because then I don't have to outsource the welding; and the weight increase of steel would be mostly offset by using less material

-Greg

[xe1ufo]

Just use 2" x 2" steel angle and it will only weigh 10lb more than the aluminum.

Andrew

Mr. Andrew: I went to the steel place here in town to check it out for mine. 2" by 2", how thin is still safe for my bug teardrop project? The man said maybe 0.12 or 0.15, I believe inches.

Can an A-frame chasis like the one you show, with no crossmembers but the axle, for the Superligera handle a 4- by 10-foot Teardrop size safely?

Thanks in advance!

[Roly Nelson]

Greg, I just checked your profile and have no idea if you are located in Alaska or in the desert in Arizona. If you don't need the insulation of the foam, the fiberglass work seems a bit overboard. I hate to work with that stuff, I itch for days after the endless sanding, so I stick to wood, wood, wood. My tear has 1/4" sides, is very light, has no insulation, (So Calif, you know) and is very light.

Now if you want to build a super-light teardrop, (less than 300 lbs), I just built one, is rather short, but sure is light. 1/4" sides, 1/8" top and only 6 ft long. However, if it were 10' long, like you are proposing, perhaps it would weigh "a few pounds more".

Welcome to the board, continue to ask questions, and by all means, take lots of pictures, since you can't go back and take them later. The type of construction you are suggesting is a bit unorthadox, so, I for one, would be very interested in seeing how it all goes together. Good luck on your build.

Roly, the lil' ol' woody teardrop builder.............ME!

[mikeschn]

Just use 2" x 2" steel angle and it will only weigh 10lb more than the aluminum.

Andrew

Mr. Andrew: I went to the steel place here in town to check it out for mine. 2" by 2", how thin is still safe for my bug teardrop project? The man said maybe 0.12 or 0.15, I believe inches.

My Tab uses something similar. But since the frame is also the tongue, they have quite a heavy cross section.

And my Lil Diner chassis uses 1/4" wall tube, with 3/16" wall tube for the tongue.

If it were me, I would probably build the Superleggra frame out of 3/16" tubing.

But I am waiting for Andrew to come back with his engineering calculations and tell us how many "daves" is safe, and what size tube that equates to!

Mike...

[angib]

I think the strength required for the tongue depends not only on how heavy the trailer is and how long the tongue is, but also on the expected use, or abuse. With that proviso, I'd say:

- 2" x 2" x 1/8" angle would be suitable for a really light trailer (say 300-400lb), with a reasonable length tongue, that would only be taken off-road with care.

- 3/16" thick angle would be more appropriate if one of these limitations didn't apply, or if more durabilty was required. On the Superleggera, going from 1/8" to 3/16" angle would increase the chassis weight by 15lb.

- The next step is 1/4" thick angle - but there is not a lot of point using this, as 2" x 2" x 1/8" square tube is the same weight but twice as strong. However, for comparison, a tongue of (twin) 1/4" angle would be as strong as the single square tube tongue on Dave Nathanson's (full-weight) trailer that failed in continued hard off-road use - so that would be strong enough for me.

But I would stress the important thing is to leave out unnecessary frame members, rather than reduce the strength of the tongue too much - and really everything except the tongue is an unneccessary frame member. Contrary to what I suspect many people think, the frame is not the equivalent of the foundations of a house!

Andrew

[RAYVILLIAN]

Andrew
I know that this is an older thread but I think kinda slow at times.

I was wondering if this frame design would work under a larger trailer like the Winter Warrior design. Say use 2 x 2 x 1/8 inch tube with some angle cross bracing at the axle. Or shoul I look at 2 x 3 like my present frame with the aframe design and alot less cross bracing.

My only problem with the warrior I built is the weight (1600 lb.) and with the 2x3 tube frame with several cross braces and steel fenders the trailer frame seems the best place to start cutting weight down.
Thanks
Gary

[angib]

I was wondering if this frame design would work under a larger trailer like the Winter Warrior design.

Whoa there! You've got me worried now so:

An A-frame chassis of 2"x2"x1/8" angle as illustrated above is suitable only for very lightweight trailer bodies - for example, a trailer with any 3/4" ply in its construction is too heavy for this chassis.

OK, with that out of the way, back to the Winter Warrior! The size of this trailer and the complexity of its lifting top means that it is never going to be less than medium weight, even if built as lightly as possible. So it's going to need a certain amount of strength in its tongue. My gut feel is that a 2"x2"x1/8" square tube A-frame is probably a bit light and if there's space for 3"x2"x1/8" rectangular tubes, they are both stronger and lighter than 2"x2"x3/16" square tube.

If using a torsion axle like the Torflex or Flexiride then there isn't really a need for even a cross-member - the axle will provide that. If using separate left and right torsion units, a cross-mmeber is required to bolt the units to. If using a leaf sprung tube axle, the need to provide spring seats in two places each side means that a more complex chassis is required.

Every other (steel) cross-member isn't worth having if you're building a light trailer. If you don't care about the weight, then adding cross-members isn't going to do any harm, though it won't make the trailer much stronger either. The Winter Warrior is a bit of an exception to this as one thing it lacks is a bulkhead or any continuous structure across the back - so this is one trailer where a rear cross-member would be a good idea.

I like to see a connection between the chassis and the side walls at some point - either on the ends of the A-frame, like in the picture above, or on the ends of a cross-member at the axle. For the Winter Warrior, with wheels inside the side walls, that means the chassis has to continue well behind the axle.

Here's a drawing of what I'm thinking of for the Winter Warrior:


(I should warn you that this is drawn on the metric version of the Warrior that I have!)

Andrew

[RAYVILLIAN]

Thanks Andrew

What you've drawn looks alot like what I was seeing in my head. I was thinking the 2 x 2 x1/4 inch cross brace because I was considering the 2 peice flexride axles that way if there is a problem down the road I can replace them easier. My version of the Warrior is 5 ft wide with the wheels outside the body and the axle cross brace would allow me to run the frame tubes further in at the axle point for that also. I can see what you mean about the rear cross brace with the door in the back that is a weak point and would be needed. I'm also considering another brace between the frame rails at the front of the body just to keep the rails from spreading.

Thanks again for the advice.
Gary