Transforming my trailer via "the template"
 

So I bought this old trash trailer a while back. It's been handy. Use it for dump runs, camping, getting lumber, whatever. But... it's falling apart!

Here it is when I first got it...
http://i95.photobucket.com/albums/l1...530_170203.jpg

The final straw was when I took it camping and the tarp was blowing all over and things fell out... that's a huge no no for me. My car also wasn't liking pulling it with as much weight as it had, not to mention jumping on the highway with it, was tough to pull. So...

The new trailer's design must be as reasonably aerodynamic as possible to make it easier on my little car to pull. On top of that, the lowest weight possible, without sacrificing the strength needed. Finally, go to LED lighting to take a little less electrical drag off the car. With all that in mind... here's the log!

I used the template and Google Sketchup to design it. Here's the overall view of that combo...
http://i95.photobucket.com/albums/l1...g?t=1403549216

I designed it to use a 2' high sheet for all the sides and went up from there. This gives me enough room to do what I need and makes it easier to use a 4 x 8 sheet cut in half.

So, I made the new sides... (Ignore all the crap in the background, this new trailer should inspire me to clean it all)
http://i95.photobucket.com/albums/l1...g?t=1403548885

Started the top...
http://i95.photobucket.com/albums/l1...g?t=1403548895

Top almost done...
http://i95.photobucket.com/albums/l1...g?t=1403548899

Found a sheet of coroplast for $5 locally that was larger than a 4x8, so it covered the entire top without using multiple sheets! It was damaged, hence the $5 price tag...
http://i95.photobucket.com/albums/l1...g?t=1403548903

Top opens...
http://i95.photobucket.com/albums/l1...g?t=1403548907

After doing the sides and the top, I decided the floor was pretty trashed, plus the folding feature of the trailer was unneccesary, so I removed the original flooring and bolted the thing together, then added a new sheet...
http://i95.photobucket.com/albums/l1...g?t=1403548912

Threw together a partial belly pan...
http://i95.photobucket.com/albums/l1...g?t=1403548915

Gave the axle bar a tail (used Sketchup and template to give me a good idea on the size/shape) and closed up the bottom...
http://s95.photobucket.com/user/node...tml?sort=3&o=4

Ran out of silver duct tape, had to go to my red reserves... lol! (More crap everywhere... swear it'll get cleaned after this trailer's ready!)
http://i95.photobucket.com/albums/l1...g?t=1403548929

Primer all. I will be painting it the same color as my car ultimately...
http://i95.photobucket.com/albums/l1...g?t=1403548934

And finally, where I'm at right now: The tail! Here is the template I'll be using to route out the main frame...
http://i95.photobucket.com/albums/l1...g?t=1403549635

I still have a lot of work to do. The tail is going to be a challenge, but it's mostly designed. Just lots of angles to be had!

I should have most of this trailer done in the next week, weather and time permitting. I'll keep this original post updated.

Cool! How about some wheel farings? I'd check the wheel bearings also, they can be a drag of a different type. Neons those years have good power as long as they aren't the 3speed autos. I had a 98 Dohc 5 speed I custom ordered new. I wish I still had it as it was fun and had no problem getting 40. I see you are getting 50.

Is there a reason for putting the vertical bars on the outside? Those do creat some drag I think.

gap
 

If you can figure a way to kill the gap you're really golden.
http://i1271.photobucket.com/albums/...titled-6-1.jpg

two things...
-The lined up well with the 2x4's that hold the gates up.
-I needed as much room internally as possible. Do a lot of trash runs, don't want things getting caught up on them from inside.

something to note: The 2x4's are planned to be "aero" as well. I did a 3/4" chamfer on the front. I have a foam cutter on the way and will be doing the boat tail on the end with foam, then glue and paint it in there. Now, that doesn't help the lip on there, but figured I'd mention this. I'll likely add the tail for the lips on the actual boat tail for the full trailer, which should help a bit.

What are you gonna do with the front of the trailer? What about a deflector, like a scaled-down version of the ones used in the cab of big-rigs, to be mounted in front of the cargo box?

NoD, it looks great! Good luck! :D

It's looking good so far. Are you going to taper the boattail in plan?

That was a good score, getting >4x8 coroplast for $5.

I have a sketch of what I'm wanting (using the template, once again), but it'll be a bit before I'm ready to build those. I also did check the wheels, they spin easily and freely!

I have that planned out, too. I will make a frame and force cover with coroplast or similar material. Ultimately, I'd like to make a door to it and keep a spare tire and maybe some bungee cords and such in there.

Yeah, just like in my diagram in the OP, as well as doing a top-down view taper as well. I've got it planned out, just gotta find the time/motivation to get it done. Hoping to route out from my template today on some ply, but again, time... motivation... blah.

Thanks everybody for the kind comments. Hoping to have this thing at least street usable by this weekend. Tail lights are preventing me at this point, which means I need to get that tail section done!

I have seen similar setups in camping trailers.

Looking great!

The 2x4s on the outside of the box... why not just "skin" the sides with a sheet of coro over the members like you did on the bottom. It should be easy, just staple gun it on the outside.

https://dl.dropboxusercontent.com/u/...ed/aero2x4.jpg

I'm actually planning to make each one a little more aero. I already have a 3/4 chamfer on the front of the 2x4 w/ some belt sanding. Next up is to cut some sheets of foam out for the tail end, then use the belt sander to give it the last bit of shape. I think this should be the most effective way to go.

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4x8 sheets of 1/2" foam board can be used anywhere structural integrity is not needed. They can be bent and or twisted into nearly any shape desired. Complex, compound curves are possible. Your same belt sander can be used to feather the edges of the foam if needed. You can glue, tape or screw it down with fender washers.

Keep up the good work... :thumbup:

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I agree that the external stakes are an opportunity. Add ribs top and bottom. The top one can be a 3-4" radius (since you've already cut the top piece) that tapers to 0 at the ends, max width 70% of the way between the stakes. The beveling helps.

Fenders? Get a surfboard off Craigslist and cut it in half:
http://ecomodder.com/forum/member-fr...ture4982-a.jpg

You could skin the sides and even flex the lower portion out over the fenders making a nice skirt/wheel faring that is basically a nice smooth side.

Alright, got some work done...

http://i95.photobucket.com/albums/l1...626_195648.jpg
http://i95.photobucket.com/albums/l1...g?t=1404135178
http://i95.photobucket.com/albums/l1...g?t=1404135283

I got a chance to pull it with a good heavy load this weekend. Going into EOC, it was much smoother than prior. I could glide just about as good as if the trailer weren't there! I still have some testing to do, but so far, my car seems to appreciate my efforts.

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Looking good... :thumbup:

>

It looks sufficiently stout. Were the joints glued as well as screwed?

Tell us about the gray twisted thing. Bungee? Taillight wiring? And the holes between license plate and taillights. Rear view cameras?

Glued and screwed. Some got the nailer because of tough angles. Clamping where possible.

Bungee, yes. I wanted to have a bit more support on the rear pulling it up. Bungees were too long, so I twisted them up to give them a bit more tension. I've swapped this out for shorter bungees now.

Tail light wiring was pretty easy. Used 18 gauge speaker wire as these lights pulled little power (LED). I used a trailer 4 pin connector at the tail to rear gate to make the tail able to come off easily. There are also license plate lights on there. Wasn't sure if it was required legally, but was cheap enough, so went with it.

The holes on the rear were in case any air made its way inside the tail. It would be a parachute if so! I don't have it completed yet, so I know it's not as sealed up as needed. So I figured it wouldn't hurt to give the air somewhere to go if it did get trapped in there. Plus... weight reduction? lol.

Backup camera... hmmmmm... I do have one laying around. Might have to consider this option! lol.

Good job on the trailer.

I thought that I had a pic of Steve Delaire's aero trailer. His was 2D shaped much like this car.
http://ecomodder.com/forum/member-fr...ture4982-a.jpg

Teardrop shaped when viewed from above. I recall that it was about the same height and max width as his vehicle.

He used it to haul his bicycle streamliner. Told me that it improved his fuel mileage 3mpg when towing with his van.

He shaped the main structure (1" square tubing) by screwing appropriate wood blocks onto the deck behind his home. Then he pulled the tubing around the blocks making 4 equally curved shapes and spaced them with straight sections. The door was on one trailing panel. That had a piano hinge with the clasp at the point at the back.

Varn, I was curious if the trailer shape you describe would be prone to sway problems. That shape would be better for a stand up camper then the traditional teardrop style but I'm worried it will wag like a happy golden retriever.

IYO hersbird, who do you think it to be unstable? The way Steve described it to me it sounded win/win. Particularly considering the lightweight quick build. I am pretty sure I took a pic.

Back to the topic....

I don't know, I'm just asking. Most aircraft need a vertical stabilizer. I just wonder as you start to get slippery upright especially if there is a slight difference in manufacturing side to side or a cross wind if it wouldn't start to load and unload and just keep getting worse.

wag
 

I've no data for trailers,but VW had a 'drop' form body,created by Rolf Buchheim and his associates in 1981 which is shaped like Varn's description of Delaire's trailer.
This 'car' had around Cd 0.16-0.15.Nothing is mentioned about directional stability in Hucho's book.
In Hucho's section on trailers he does mention that leading edge radii can impact yawing moments.
This trailer body type would make for a nice graduate,scale model wind tunnel study.

http://veloliner.com/dmn06/63006/P6300008.JPG

Delaires bike is in the background. His trailer is opened up, the rear right side is opened forward exposing the inner panel of left side. It is difficult to visualize the shape but you can get an idea of its size.

It sounds like your concern is with a vortex street. You'd get that with too low a fineness ratio.
http://upload.wikimedia.org/wikipedi...-animation.gif

Is that what brought the Tacoma Narrows bridge down?

After reading the wiki article it says Aeroelasticity is what brought the Narrows down.
Yes this is the kind of thing I would worry about. In a car or bike with wheels at each end there shouldn't be a problem but on a single axle trailer already potentially with sway a problem, I just was wondering why we haven't seen boattail trailers since the earliest days.

Ummm, we have....
http://www.tincantourists.com/wiki/l...ia=bowlus1.jpghttp://www.tincantourists.com/wiki/doku.php?id=bowlus#.U7Q3Ver-mkI

sway
 

My single-wheeled trailer went across Texas,New Mexico,and Colorado at speeds up 80-mph and I experienced nothing unusual in handling.
She is a 'pumpkin seed' design,rather that a section/strut,so I can't vouch for those,but a 'classical' half-body is rock solid on the road.
Goro Tamai of MIT reported in his 'The Leading Edge' that these flattened torpedos are very stable,including crosswind gust.
http://i1271.photobucket.com/albums/...d2/Honda-1.jpg
http://i1271.photobucket.com/albums/...Untitled-9.jpg

Herbird. Most people from truckers to campers want to have maximum usable space. A pointy rear shape is bad for that. Also remember that it has only been in the last 10 years that fuel prices have become outrageous. I sold my motorhome when the price went to $1.75, outrageous.

I have been moving for some months. We use a 12 foot 4 wheel flat bed trailer behind our OD vehicle. To enclose it in an ice cream cone would be fruitless.

Once things become stable here we plan on modifying our two wheel motorcycle trailer with an aero shape. It will be a steel frame and maybe a metal skin like a semi-trailer. Welding steel is so easy and light weight I couldn't imagine making one from wood.

A pointy rear is really just a square turned 45 degrees. I figure I will use the space like a v-berth on the front of a boat but in the back instead, also with feet to the back the tapering headroom won't be a problem there either. As long as I have a 4' long by 6' wide price of floor with 6' headroom in the middle I'll be happy. Then a sleeping pod section maybe with hybrid style tent pop outs. The smaller of modern box trailers are 8' wide, 12' long with 6.5' headroom front to back, so much more then a couple needs IMO. Boat builders use space well, I'm thinking more like that while not killing the economy not to mention the mechanicals of the tow vehicle to the point I can't afford to go out for a week or weekend. I can't go too crazy with the radiuses or it will be to difficult to build.

Actually a better comparison would be: en.wikipedia.org/wiki/Vesica_piscis

http://ecomodder.com/forum/member-fr...17-trdrp1a.jpg

Here is a design where the radiuses couldn't be gentler. It's actually a good approximation of the Template shape, stretched vertically.

Just the opposite of the Bowlus; the door is at the rear, in a truncation. The pointy end has a 90° angle in the front. Here's the frame laid over a teardrop outline.

http://ecomodder.com/forum/member-fr...-trdrp-frm.jpg

http://i1114.photobucket.com/albums/...170435_744.jpg

Frame1

Frame2

Rear left

Rear open

Rear open 2

Comments from builder's brother:

"Full round front nose. Should weight 1200 empty"

"He built scale models and a 6 foot windtunnel to design the shape. He's pretty sure it'll help get as good or better mileage vs. The towing vehicle by itself."

"The drag coefficient with his full-to-a-point trailer design is so crazy low....its really more about how you put the air back together than how you take it apart. He saw Lower drag (in models) with trailer than without..... and he theorizes that it'll be quite a bit more dramatic at full scale, obviously."

Behind a full sized van that might work ennored, behind that little car it looks like a whale.

A great, white whale.

I'd split the tail and put each side on 4-bar linkages so they swing out and forward. Like a minivan door before it starts to slide. It might not work without taper to the top.

It has some taper on the top, but not much. It was obviously designed to be able to made easily, all flat sheet aluminum. And to be able to get a car into it.

Given that a square box can have a drag coefficient as high as .8 or more, this should pull great. Try towing a regular enclosed car trailer with a Nissan Maxima, ain't gonna work.

I like that trailer, taper the top some, put a door and some Windows on it, dont need the ramp and rear doors, and that's what I'm thinking. Look at how low it rides compared to the average camper, the up sweep on the rear help with overhangs and aero. Still tons of space inside.

That's a well-used race car. :)

The truss work and triangulation in the side walls look good. The air bag doesn't point at the trailing arm; maybe there's a rocker arm in there.

Did you see this or just find the pictures? I'm curious whether they left the lower rear open. And how they get the car in and out.

Found it in another forum.

There's a "floor" that drops down from the right side rear door. The air suspension lets the tail of the trailer drop right to the ground. It's dropped in the "Frame2" linked picture.