5x8 design questions

[DesertApprentice]

Hello, newbie here, this is my first post. 

I'm designing a 5x8 square teardrop from ground up. My towing vehicle is a 4-door JL Rubicon. I want a light-weight off-roading camper.
I found a design online, and modified it. Here are the 3 sketches.

 

I have no prior building skills. I bought a welder a few months ago and did some practice. I have many questions about the frame design.

1. I hope the overall frame design is sound. Any constructive or destructive feedback is welcome
2. For the metal, the plan is 1/4 inch 2x2 square tubings for the frame, but the tongue (3 pieces) will be 3/8 inch 2x2. Does that sound right?
3. Is the length of the tongue correct? The design criteria is that my Jeep (with a big 37" tire on the backdoor) can turn freely without jackknifing and hitting the camper. I plan to have an off roading articulating coupler like etrailer lock n roll. Etrailer has so many options,I'm sort of lost. Any particular recommendations?
4. I plan to use Timbren axle. etrailer.com has 2000lbs / 3500lbs. I need the package with the electric brake. It's very pricy. Any alternative? https://www.etrailer.com/Trailer-Axles/ ... S545E.html

For the tire, I plan to use the original 33" tires from my Rubicon. My Rubicon currently has 37" tires.

I'm going one step at a time. I don't have a clear plan for the actual cabin yet.

Thank you all in advance!!

 

[Tony Latham]

What jumps out at me is your axle placement. It's too far forward. It needs to be at about the 40/60 point on your frame (excluding the tongue). Otherwise, things could get really exciting on the highway. (And I realize you've got your spare up front, but still...)

The other thing is your material thicknesses.

For the metal, the plan is 1/4 inch 2x2 square tubings for the frame, but the tongue (3 pieces) will be 3/8 inch 2x2. Does that sound right?

That's much too heavy. For the frame and tongue, you can go .120" 2x2" tubing. I might also suggest .120" angle for the cross members. Yes, I'm talking off-road stuff.

And since you can move the axle back. Move the doors back too.

Door placement is critical. Put your computer down for a moment and go lay on your bed. Now sit up and swing your legs off as if you’re getting up–but sit there for a moment. Note that this is the same place that you sat on the edge of the bed before you laid down. Your pelvis will be about 30 - 33” from the headboard. This is where the doors need to be–right next to where your hips rest when laying down and where you normally sit on your bed.

And yeah, I used the plural form of doors. Assuming you have a significant other, try using one side of your bed for three nights. And then try making the bed from that side only. Two doors.

Now... I see you are planning to make it 5'4" wide. Two-bits says that's so you can get a queen mattress inside. That extra 4" can cause additional challenges with building materials. You can fit a high-quality 60" foam mattress in a 58" (interior) camper cabin just fine. After all, it's foam.

You'll also have additional challenges because of your 4' 4" height because of material widths. A cabin (external) height of 48" will give you more sitting up headroom than your Jeep has.

That's my six-bits. Or is it eight?

Tony

 

[Shadow Catcher]

Our tear is a 6X10 and the head of the bed is in the rear, the water tank is also on the rear and is kind of the headboard. The advantage easy to sit in a scootch backwards cabinets for and aft, lots of storage.

 

[wysedav]

Hi where was the design that you started with? I'd like to use it if it's available

 

[DesertApprentice]

Hi where was the design that you started with? I'd like to use it if it's available

I'm not good with sketchup. I can't figure out how to share the link. Here is how I find it: start a new drawing in browser, then click on 3D models (right hand side), search for "teardrop", select "models", then browse through. There are several you can choose. If you want to hit the one I was using earlier, try search "Copie de Offroad Teardrop Trailer 2". Good luck!
@ wysedav, BTW, I don't mind sharing my design with you after I put it together. It may take me some time to get there as I'm learning sketchup as well.

 

[DesertApprentice]

@tony.latham, @Shadow Catcher Thank you so much for the feedback!!

I redrew the design from the scratch. Here is what I have got so far (I'm designing the frame first, I'll worry about the cabin design detail after):

Based on the feedbacks:
1. I will use 0.120" and 2x2 tubing for everything.
2. I have cut the frame to 5x8 exactly, mimic the sample design as shown by Tony.
3. I moved the axle to the back, now the axle center is at 5' (from front), or 3' (from the back).
4. The tires in the 2nd drawing are shown in the approximate location. Given it's 33" tire, i figure the front edge of the tire is roughly 3'10" from the front. I suppose this is as far as the door (right edge) can go.
5. I will have 2 doors. We have my wife, I and our dog in the cabin.

Got two more questions:
1) Tony's sample is 5x10, the width is 59 1/2", not 60" (5 ft). Any particular reason for the odd number?
2) Assume the right side of the door can be placed up to 3'10" from the front, will that accommodate the final door location ? I don't even know the size of the door. I just want to make sure the frame/tire layout has enough space for the door when i start to work on the cabin.

I really appreciate everyone's input. Thank you very much!!!

 

[Socal Tom]

I would also take a look at where the springs will mount to the frame, and I'd put cross braces in that location, instead of directly over the axle. That is where the weight will transfer, and that is where side loads would transfer to the frame, so that is where you want to put the bracing. It also gives you someplace to mount shocks
Tom

 

[DesertApprentice]

I would also take a look at where the springs will mount to the frame...

Thank you for your response, Tom!
I plan to use Timbren Axle-less suspension. Since there is no real axle or spring, I suppose that "axle" in the drawing indicates roughly where the reenforce bar is.
I'm thinking not to weld in that bar initially. I hope to nail the exact location after I get the Timbren suspension.
The only thing I know about the Timbren suspension comes from Youtube. I hope my plan makes sense.

 

[QueticoBill]

I suspect the 59 1/2 is to allow 1/4" ply sides to come down outside frame. If you're making cabin permanent on frame, probably a better detail for water - the common enemy of buildings of all types.

 

[working on it]

Our tear is a 6X10 and the head of the bed is in the rear, the water tank is also on the rear and is kind of the headboard. The advantage easy to sit in a scootch backwards cabinets for and aft, lots of storage....

* Mine's a 4x8, with 48" tall ceiling, overhead shelves fore and aft. The head of the bed is also in the rear, where the bulkhead separates cabin from storage/galley. I used to be able to slide in (under the overhead shelf between the doors), and out easily, but had to add an overhead "trapeze" bar to lift myself up and out (I'm 70, with bad back/knees).

*

What jumps out at me is your axle placement. It's too far forward. It needs to be at about the 40/60 point on your frame (excluding the tongue). Otherwise, things could get really exciting on the highway. (And I realize you've got your spare up front, but still...)

* When I modified my original frame (50"W x 60"L) to 50" x 96", I added 2 ft to the rear, and 1 ft to the front...a mistake. It should've been the reverse. As it was, my axle centerline ended up at 52" front and 44" (54%/46% F/R). I complicated the balance problem by having the bulk of the trailer's weight in the 22" deep storage area (generator, A/C unit w/ducting, 7-gallon water container, rear cooler, Coleman lantern & stove & fuel, etc.), making the tongue weight too light (even with the spare on the front wall, and the battery in a small box).

* I fixed the imbalance over the years, by putting a large box in front (with battery and many heavy items inside), racks over the tongue box (with heavy gear loaded on), and removing the water jug & lightening the cooler in the rear compartment. So, the apparent imbalance is now effectively solved, with 266 lbs tongue weight and 2222 lbs total weight (12% tongue weight).

* Though the light tongue weight made me modify several things, and devise workarounds for safe towing, until the final configuration was arrived at, If I was to do it again, the axle would've been at 60/40 and the generator would've been in the truck bed, not in the trailer.

 

[Tony Latham]

Tony's sample is 5x10, the width is 59 1/2", not 60" (5 ft). Any particular reason for the odd number?

It's so an aluminum-sheathed cabin doesn't sit on the bottom trim.

Tony

 

[Socal Tom]

I would also take a look at where the springs will mount to the frame...

Thank you for your response, Tom!
I plan to use Timbren Axle-less suspension. Since there is no real axle or spring, I suppose that "axle" in the drawing indicates roughly where the reenforce bar is.
I'm thinking not to weld in that bar initially. I hope to nail the exact location after I get the Timbren suspension.
The only thing I know about the Timbren suspension comes from Youtube. I hope my plan makes sense.

Makes perfect sense,
Tom

 

[rjgimp]

4. I plan to use Timbren axle. etrailer.com has 2000lbs / 3500lbs. I need the package with the electric brake. It's very pricy. Any alternative? https://www.etrailer.com/Trailer-Axles/ ... S545E.html

I have never dealt with them in any way but my understanding by reading others' accounts is that NO ONE is having a good experience lately with etrailer. They are so short staffed they just can't get stuff out the door. I was reading a build thread yesterday where the guy was describing his experience as having ordered AND paid, been told the item is IN STOCK, had already been waiting something like 8-10 weeks, and kept getting the expected ship date pushed back. He finally told them to pound sand, cancelled his order, and got it directly from the manufacturer in a few weeks. It just seems that the hurrieder etrailer goes, the more behinder they get. I visualize 100 new orders coming in every day and they only get 50 shipped, so every day they get 50 more orders behind.

May the odds ever be in your favor.

 

[DesertApprentice]

I started with the cabin design. I looked up many ideas online. I have come up with these 2 exterior concepts. The main difference is the spare tire placement. I'm leaning towards placing the tire on front cabin wall. But that obviously is a more difficult choice. I like it because it looks cool , but wife is poo-poo-ing the idea Not all adornments in the drawing have precise dimensions other than the frame. Given my very limited skills with sketchup, once the concept is vetted out, I plan to fill in the final dimensions with paper and pencil.

I have no prior fabrication experience. I imagine a ton of challenges with my non-conventional design. I'd like to hear your feedbacks. I especially want to know if there is something totally stupid with the design.

Here are the overall considerations:
1. 5x8 frame, cabin backside extends 1 foot out, 2 side doors, 1 back hatch. 33" Jeep Rubicon tires (left over when I upsized my Jeep tire to 37").
2. I do moderate off-roading, i plan to use Timbren axle-less suspension with E-brake. I also looked into Dexter Torsion axle, when all said done, it's just slightly less than timbren. but I can't find sufficient information on torsion axle.
3. full exterior height is TBD, my requirement is for it to fit in my 82" garage entrance. As shown the drawing is ~75". Highest interior point is ~52".
4. I do not plan to have a galley. The back hatch will open, there is a pull out "kitchen". It's similar to tiger moth https://taxaoutdoors.com/habitats/tigermoth.
5. Inside will have a convertible bed/sofa

Thanks a lot everyone!!

 

[DesertApprentice]

since one post only allows 2 attachments, here is the kitchen and hatch door concept

 

[Tony Latham]

Where will your hinges be on the doors? On top?

Tony

 

[DesertApprentice]

Where will your hinges be on the doors? On top?

Tony

That is the plan. I'm actually intimidated at the thought that I need to fabricate my own doors due to the odd shape and dimension.

 

[eLink]

since one post only allows 2 attachments

The trick is to upload images to your Gallery first, then you can insert as many as you like into your posts.
Check out this link:
http://www.tnttt.com/viewtopic.php?p=911290#p911290

 

[Socal Tom]

since one post only allows 2 attachments, here is the kitchen and hatch door concept

Have you thought about having the drawer come out of the side?

 

[DesertApprentice]

The trick is to upload images to your Gallery first, then ...

Thank you very much for the tip, eLink!

Have you thought about having the drawer come out of the side?

I did think about that. I'm still open to ideas.
Here is my thought: I like the idea of a hatch door in the back that can also be an entry door. A remote benefit is I could put larger items inside the trailer, it provides a limited utility function. If I do side pullout, it will need be at the front. A "kitchen" is at the front might be away from other stuff. Also the front side real estate is blocked by the tongue. Another tangential benefit of pulling out from the back, the pulling handle is covered inside the back hatch door, one less hole I have to cut on the wall.