Utility trailer hack (building an aero enclosure for a 1100 mile highway trip)

[KamperBob]

This is a project thread. I'm preparing for an 1,100 mile trip in a couple weeks. I will be towing my utility trailer loaded with some biggish stuff. I have enough prep time and scrap material to hack together a shoestring shell with some aero features. Here is the plan so far.



The trailer has a 5x10' deck. I'm widening it to 6' to swallow half of each fender. Those nose is a 3' semicircle. The final departure is 20 deg. The top will be 6' high and flat. The bottom 2' of the sides truncate half or 18" of the nose. That works out to a 30 deg approach 3.5' behind the truck so pretty much shadowed by the tailgate. The upper 4' extends 1.5' closer so it's only 2' behind the tailgate. The curved nose starts a little below the tailgate and ends well above cab height. So that will part the flow coming around the cab and across the tonneau cover.

I considered several variations. This design has some elements that I am keen to field test. Hopefully flow will stay fairly attached.

Opinions?

Cheers
KB

[MadisonMPG]

Lose the fenders. Why not slope the roof?

[KamperBob]

Originally Posted by MadisonMPG

Lose the fenders. Why not slope the roof?

Gasp! I'm not cutting the fenders off the trailer. Have you ever experienced tire failure? Safety first.

This is literally a one-off trip. When I get there the trailer stays and the shell gets scrapped. I'm also balancing time and cost budgets. And perfect is the enemy of good enough. (occupational hazard)

However, what I learn from this field test will inform future projects.

Cheers
KB

[Angmaar]

If you could smooth out the corners around the top some more the trailer would be more aerodynamic.

[MadisonMPG]

Originally Posted by KamperBob

Gasp! I'm not cutting the fenders off the trailer. Have you ever experienced tire failure? Safety first.

No, never have, and no one I know has either. I guess it has something to do with watching how you drive and good tires?

[Bicycle Bob]

I second the notion of having more rounding at the front. It would not be hard to make a curve in the top that matches the sides. A well-taped Coroplast seam would probably be sufficient. Use matching colours of duct tape for a classy look.
I'd also add simple fender skirts that curve out and back in to finish enclosing the wheels.

[KamperBob]

Originally Posted by Angmaar

If you could smooth out the corners around the top some more the trailer would be more aerodynamic.

I agree in principle. My no-cost material is a few sheets of masonite based paneling. Pretty stiff. A 36" radius is as tight as I dare bend it. Compound curvature is not possible. I'm doing what I can with free material. Every 1 mpg (6%) gained only saves 10 bux in gas. With a life expectancy of 1 trip I cannot justify throwing any money at this project. The only reason I'm spending time is because it's fun and all experience is good.

Cheers
KB

PS- If anyone wants a free trailer box that looks like crap and smells like pee (feline no less) all you have to do is come get it!

[thatguitarguy]

If you have a circular saw you can kerf the inside of a sheet of Masonite and it will curve a lot easier. Masonite is about 1/8" thick, so set the saw to about 1/16" deep and cut lines 1" apart perpendicular to the way you want the board to curve, or for a curved edge you can cut the lines closer together.

[KamperBob]

Originally Posted by thatguitarguy

If you have a circular saw you can kerf the inside of a sheet of Masonite and it will curve a lot easier. Masonite is about 1/8" thick, so set the saw to about 1/16" deep and cut lines 1" apart perpendicular to the way you want the board to curve, or for a curved edge you can cut the lines closer together.

Good tip. A guy could probably tighten the curvature down to a foot, possible less. I don't see that making compound curvature possible though. Still, good idea for some.

Cheers
KB

[KamperBob]

Originally Posted by Bicycle Bob

I second the notion of having more rounding at the front. It would not be hard to make a curve in the top that matches the sides. A well-taped Coroplast seam would probably be sufficient. Use matching colours of duct tape for a classy look.
I'd also add simple fender skirts that curve out and back in to finish enclosing the wheels.

So where does one find coroplast? What kinds of stores carry it locally? Perhaps more importantly, what does it cost? How much per sheet?

Cheers
KB