Out with the old and in with the new

[mdk]

I mentioned elsewhere that my previous wants have been negated, and so this is a new thread... New ideas needed.

I wasn't all that concerned originally about aerodynamics, but since now I'm going to live somewhere that's AT LEAST a 1000 miles from anywhere worth going or being, I've now got far more interest in designing a light and easy to pull trailer, and it still needs to be 4x4 road worthy. I'm only a half hour's drive from some spectactular back country now, but there's not a decent mountain for hundreds of miles from the state of Illinois...

Anyway, here's the criteria for design and implementation:

As low as possible wind resistance.
Not heavy (under 2500 lbs dry)
at least queen sized bed.
large fresh and holding tanks ( 60 gallons or more)
fully self contained.
15 inch tires
double axle
high ground clearance

It has to have some "room" inside. That is, I'm going to want space for a computer monitor and plenty of food storage, a larger than average fridge and an oven.

More later... It's time to take the wife and our two dogs out and escape the heat in the mountains.

[mdk]

Does anyone have any links to useful information on how to reduce drag?

Ok, so it's my intention to build a box on wheels... but I'd like to make it as easy to tow as possible, without dramatically bunging up the useful space inside.

I've found a lot of threads here talking about the effects of drag and one of the means of reducing it is the teardrop, except I'm not interested in a teardrop, but in a semi=conventional travel trailer style, of completely non-conventional construction.

Has anyone out there found or collected what it means in terms of improvements to say, slant the nose, or make a v-nose, or other modifications?

For me, this is where I want to start.

[Woodbutcher]

You have me confused a little. You want light weight (under 2500lbs) and double axle. High clearance low drag. Those things don't fit so well here. Why do you want such a big trailer and double axle? I feel your pain moving to Illinois. No place to offroad here, so where will you use this large trailer? I think you will need to compromise on some of what you want. The good news is we have a fairly active group of teardroppers here in Illinois and hope you look us up when you get here.


Steve

[mdk]

You have me confused a little. You want light weight (under 2500lbs) and double axle. High clearance low drag. Those things don't fit so well here. Why do you want such a big trailer and double axle? I feel your pain moving to Illinois. No place to offroad here, so where will you use this large trailer? I think you will need to compromise on some of what you want. The good news is we have a fairly active group of teardroppers here in Illinois and hope you look us up when you get here.


Steve

Oh, you're absolutely right, that high ground clearance increases drag. That's a compromise I have to make. I can still, however, adjust shapes and do aerodynamic modifications to make the best of it.

As far as off-road, I want to make some trips to Colorado (like traveling over engineer pass - not with the trailer behind over the pass), southern Utah, Death Valley, the Mohave Desert, Joshua Tree, and a bunch of other places out west.

Two axles are not required for the weight, but it does improve the approach and departure clearances over highly uneven terrain. For instance, the water tanks would go right above the axles, the blackwater and graywater tank outlet would be between the wheels, so as to be protected. The frame would need some skid protection built in.

Still, after all that, the basic shape could be tweaked for best aerodynamic advantage. And, I could use such things as Airtabs.

I've even thought about using a gooseneck type hitch and trailer. But that adds a lot of weight.

[Bogo]

For aerodynamics, look up the Foamie Aerodynamics thread: viewtopic.php?f=55&t=49036

I've been designing a trailer that has many requirements similar to yours, but maybe not as much water. I also may not be going for quite as heavy off road handling. Improved fire road is my requirement. I've been designing pop ups so I can stand up inside, yet have them mostly fit in the wind shadow of my 4Runner. I have a shower, queen bed, toilet, and kitchen as basic requirements.

You may wish to build a spreadsheet with weights in it. It is surprising how fast they add up.

Thinking on your off road use. If you store water in jerry cans. You can have storage space for a bunch of them. Then as trip needs change you can change the mix of water and fuel jerry cans to suit the trip.

This one is under 50 inches towing height with 12" ground clearance. The rounded front and rear cone both provide interior accessible storage. I was also thinking of putting a window air conditioner into the rear one. The tires are 31x10.5R15, same as my Toyota 4x4 Hilux uses. It is a three tier pop up. I did weight calculations for one like this one, 12' long x 5' wide interior. Basic body+frame+axel+wheels using Filon skinned SIP panels and a simple two rail steel frame is roughly 1500 pounds. No sliders. Adding sliders adds weight fast due to the length. Pop up lift can either be cable or compression spring.



This one was an exploration in aerodynamics. It would mostly fit behind a Toyota 4Runner. Interior width is 60", exterior width is around 70" which is 4" wider than a 4Runner. Walls are 2" foam with Filon skins. 12" ground clearance. This one has unequal lift in the front and rear. Lift would have to be by cable.



I've been working further on it after a few requirements changes. I decided to try putting in a washer/dryer which means a minimum of 34" interior height when lowered. Also decide I must have 2 Engel MT45 or equivalent refrig/freezers. One for refrigerator use, and one for freezer use. 13" ground clearance before tire compression. Note, the axle angle is set at full weight for a 3500# Dexter 45 degree down torsion axle, 10L hub style for 6-bolt on 5.5in circle wheels.


Big green thing is a queen bed 9" thick. Plan is to have it fold into a couch. Haven’t' decide if that will be crosswise or lengthwise. Lengthwise has the nod for now. The two smaller green things are Engel MT45 refrig/freezers. Big gray thing is the washer/dryer combo unit.

Red = horizontal 40# propane tanks.
Yellow = group 31 batteries.
Dark gray in the middle = black water tank, 14 gallon.
Medium gray in middle = gray water tank, 31 gallon.
Dark gray on far side = vacuum flush system (position not fixed).
Water tanks will go in the back corners, 40 gallons will easily fit, need to find suitable tanks.


Detail showing frame, axle sub frames with battery tray and 2 horizontal 40# propane tanks. There are axle sub frames that go in the wheel well area that are not drawn up yet. The torsion axle plate side bolts to them, and they also cover the opening against water and debris getting inside. Frame spacing is 34" outside face to outside face. It is shown with 31x10.5R15 tires and wheels. I need to investigate more on the Dexter torsion axle’s dimensions. There is a possible conflict between the wheel and the fixed end of the torsion arm. If there is a problem it could be gotten around by going to a larger wheel, or using a spacer and an axle with a narrower hub face width. Frame is all folded 0.10" aluminum or 0.25" steel. The tongue beams are 3"x2"x0.25" DOM steel rectangular tube. That should be strong enough for 3500 pound trailer. My goal is 3000 lbs fully loaded for camping. That gives 500lbs for food, clothing, and camera gear. All camping gear is allocated in that 3000 lbs. The tongue looks long in this image, but it has to extend out in front of the curved nose piece.



I don't have the door drawn in yet. My plan is the bottom part will always stay mounted. The top part will have a door that swings up to make an awning over the door. There will then be a frame plus upper door that will fit in that opening, and be securely latched in place with draw latches.

The kitchen sink, table, overhead cabinets, microwave oven, convection/toaster oven, etc. will be built as modules with shelf bracket hangers to hold them in place. On the walls will be mounted shelf standards for the brackets to attach to. They will be stowed in the front and rear storage areas, and on the floor when the top is down.

Black water and gray water handling. Consider going to a pumped out system. The hose and fittings can then be all tucked up inside a compartment with no external fittings to get snagged or bashed in on anything. Example: Clean Dump Macerator Pump http://www.pplmotorhomes.com/parts/rv-t ... erator.htm

[Bogo]

OK, I figured out how to lift the top and rotate it. As you can see, where it counts, the kitchen, bathroom, and shower area has full standing height. Over the bed/sofa the ceiling drops around 2 feet from the front end to the back end. I still need to add some of the surfaces in the top. I don't have the interior walls in, so the back wall looks a bit further back than it would be. The back wall would be close to where the line is in the ceiling. The cowgirl is 5' 8.5" tall.


The SIP panel for the roof is 3" thick because most day time heat gain will come through the roof. I also notice I need to redraw the top panels because the roof and front panels are supposed to overlap the side panels.

Shower splash containment and bathroom privacy is provided by a curtain hung from a track mounted on the ceiling. Shower drain floor isn't drawn in yet.

I hope the ideas I've shown will help you figure out new possible ways to proceed.

[jstrubberg]

1000 miles from anywhere? As an Ozarkian, I have to disagree. There is a LOT to see that sits below 1000 feet of elevation!

[Donutboy]

With regard to aerodynamics, how about a belly pan?

Hmmm....on a teardrop would that turn it into a wing?

[Bogo]

With regard to aerodynamics, how about a belly pan?

Hmmm....on a teardrop would that turn it into a wing?

Wing Drop...

I'd give priority to tucking the wheels under the body, then covering the wheel wells, and finally the belly pan. If you do a belly pan you really need to get the axle covered by the belly pan otherwise most of your possible gain won't happen. That is much easier with a torsion axle, and I've done it with the two rough designs I've been working on. Using a SIP based basement floor basically makes the trailer bottom smooth. Of course for off road there are some distinct advantages to having a wide wheelbase.

This is what the three tier one looked like a couple days ago.

Top lowered and ready for travel. I shortened this one a bit to 5' W by 11' 2" L interior to allow making with 3'x12', 4'x12', and 6'x12' sheet stock. That's somebody else's model of a 4Runner, and the cowgirl is 5' 8.5" tall. The highly rounded nose is to better part the air that tries to work its way between the TV and trailer. Most times you are driving, you are driving into a cross wind of some sort. That partially defeats having the trailer within the size limits of the TV. It means the shape of the outer foot or two of the trailer does matter for wind resistance.


Top up and ready for camping. Yeah, the propane tanks are floating in the air. I still have to make the supports for them, but I know they will fit under the front nose and there is space for a spare tire or generator between them.


Tops removed to show the inside. Green thing up front is the size of an Engel MT45 fridge/freezer. Queen bed/sofa has a height of 18 in.


Cut plane is just aft of the front wall. I hid the Engel box. 1" thick foam walls. Going to 2" thick walls would add 6" to the overall width. Stuff like counter, sinks, cabinets, microwave ovens, etc. will be held on the walls with shelf brackets and shelf standards. When traveling, they will be stowed under the bed and on the floor. I need to figure out an easy method for latching them down during travel.


Sea green tanks are fresh water.
light gray tanks are gray water. Notice how the balance is retained as fresh water becomes gray water. I may not keep that as it increases complexity and cost. Water and gray water tanks are 30 gallons each.
dark gray tank, and long dark gray thing are the black water tank and vacuum flush generator.
Yellow boxes are 4 Group 31 batteries. Plenty of power for a whole weekend without needing Solar or recharging. Using HighFlex Solar's panels there is enough room of the roof to VHB tape down enough panels to recharge that battery bank in less than a day of good sun. The battery bank is also big enough to run a DC Airco air conditioner over night. There is still enough room between the wheel wells to add two more batteries.
Red cylinders are 40# propane tanks.
Tires are 31x10.5R15.


Since those screen shots were made, I've rounded and extended the nose a bit more to allow a spare tire to be put under it, then stuck the spare at the back, and put the generator back on the tongue. I also changed from the tall c-channel frames to putting c-channels into the floor SIPs. This was because the tall c-channels were getting in the way of installing the furnace and water heater. There wasn't enough room between the c-channels and the outside walls. It'll be a little bit heavier, but I can now use much cheaper furnaces and water heaters.

[mezmo]

Bogo,

Do you have a Build Journal yet ? [Sorry, I haven't had time to look]
I've noticed some good posts by you of/on your planned build in other
threads [RE: On the related/shared topics in their build and your design] that
should really be located together, both as a record/archive for you and
an easy to follow progression for others to follow.

Either copying and pasting the posting, or right click on the little-sheet-of-white-paper
icon by your user name, in the body of the posting, and copy and paste the
link-to-it into your Build Journal, should do it allow you to gather them.

Just curious.

Cheers,
Norm/mezmo

[Bogo]

Bogo,

Do you have a Build Journal yet ? [Sorry, I haven't had time to look]
I've noticed some good posts by you of/on your planned build in other
threads [RE: On the related/shared topics in their build and your design] that
should really be located together, both as a record/archive for you and
an easy to follow progression for others to follow.

Either copying and pasting the posting, or right click on the little-sheet-of-white-paper
icon by your user name, in the body of the posting, and copy and paste the
link-to-it into your Build Journal, should do it allow you to gather them.

Just curious.

Cheers,
Norm/mezmo

I should do a design journal. On my computer I maintain my notes in some LibreOffice text and spreadsheet documents, plus I keep daily and major change backups of my documents and Sketchup drawings. For lots of parts, like a SIP wall, I have lists of the features, parts, where they go, and the build steps. As stuff changes I make backups so I can track the changes.

[mdk]

Well, as an update: I've settled on some ideas... One is that to simplify design and construction, I'm going to stick to 10 inch on 5 on 4.5's - that's 21 inch tall tires - means they can be fully underneath the floor and still have 5 inches of wheel travel, while not making the whole thing absurdly tall. Another, is to use a V front. Not so much for aerodynamics (almost no gain at all) but for increased space inside while having as short of a "box" as possible.

The aerodynamic situation is helped a lot by staying only 6 feet wide. the percentage reduction in frontal area by not going to 8 feet is... 25%!

I have spent a lot of time pondering the idea of a pop-up - and every time I arrive at the conclusion that it's beyond my design and construction abilities AND it introduces a LOT of complexity and fragility and weight - all of which work against the purpose, which is to explore the back country.

Yes, I'm in Illinois now... but I'm leaving someday. You can't keep me here short of killing me. I can make my temporary sojourn for a few years and then... Color me gone. And it will be to the west, probably to the west of the continental divide, possibly Alaska.

[Junkboy999]

Got a sketch of this new monster that is running around in your brain??

I find it easier to make a sketch to help he plan things out. I use the computer more and more but still have a few paper plates around with drawing on them Ha haha