CARGaerO t'ailer; a hitch-mounted boat tail (Pontiac Vibe) - Fuel Economy, Hypermiling, EcoModding News and Forum

Tango Charlie · 07-31-2012, 01:42 AM

I've decided to make a truncated boat tail for my Vibe.

It will be attached to the hitch-mounted cargo carrier that I made a while back. The first version of the cargo carrier, being made of angle iron and 1/2" plywood, was quite heavy. It also rode too low. It drug the ground a couple times when I used it.

So I made a "version 1.2" and it has worked much better. I used aluminum angle and paneling to make it lighter weight. I elevated the deck and angled it up slightly to keep it from dragging over bumps and inclines.

Then I saw the Audi with the hitch-mounted tail from the Netherlands. Well, I loved the aluminum construction, but realized it was out of the question once I priced some aluminum sheets at a nearby RV surplus yard. I nearly gave up on the idea until I remembered that Coroplast was only $12 a sheet. Hmmm... I started doodling...

Yeah, you saw it here first; the CARGaerO t'ailer. It's copyrighted.

I used seifrob's Aero Template Overlay tool to get a better idea of what I was after. I cleaned it up in MS Paint and it started to look promising.

I'm ending it 34 to 36 inches behind the rear bumper, to keep the cargo carrier deck accessible. The rear bulkhead will have a door to load luggage through. I will install a set of trailer lights and a license plate holder on the rear bulkhead/door. Construction will be almost entirely out of Coroplast.
Can I persuade the Coroplast to make the shape I'm envisioning? Will it be done before Weather Spotter and JethroBodine show up for the Labor Day Michiana Meet-Up? I'm not entirely sure. But I'm gonna try.

Frank Lee · 07-31-2012, 01:54 AM

It's gonna be nice, I can see that already.

I saw that Audi tail too, and started a mock-up on the 'Coupe...

MetroMPG · 07-31-2012, 08:02 AM

Subscribed. I've been noodling something like this for the Insight.... right around 2018 at the pace I tend to get things done!!

FYI, if you're still thinking about aluminum, one source of inexpensive thin sheet metal: rolls of roofing "flashing". It's not very wide though, so you'd have lots of riveting to do.

MetroMPG · 07-31-2012, 08:04 AM

Quote:

Originally Posted by Tango Charlie

I elevated the deck and angled it up slightly to keep it from dragging over bumps and inclines.

You mean "bottom taper angle" didn't enter your mind at all when you were angling it up?

LocoJason · 07-31-2012, 10:25 AM

This is fantastic. I have often considered doing something similar, if only to support an easily-removable box cavity instead of a full aero extension. Looks like you're off to a good start. I am eager to see how yours comes together.

basjoos · 07-31-2012, 10:35 AM

One of the cheaper source for aluminum sheets and bars is Aircraft Spruce, where you can buy it online (Aluminum from Aircraft Spruce). They are MUCH cheaper than Lowe's or even McMaster-Carr.

One problem with using Coroplast for a trailer (or anything that will be continually exposed to the sun) is that will get brittle and start to break down after a year or two of sun exposure unless you keep it painted (and paint doesn't stick very well to polypropylene).

Tango Charlie · 07-31-2012, 01:05 PM

Thanks, Frank Lee. I appreciate that!

Metro, I didn't measure the angle really. Just used TLAR (That Looks About Right). I figured that it was above the bottom edge of the bumper, and would be in the wake behind the car. I wasn't thinking of installing a boat tail when I made that modification.
Some care will be taken with the 'diffuser angle' of lower skin of the T'ailer, however.

Thanks, basjoos. Spruce was one of the first places I checked, actually. I use them quite a bit in my line of work as an A&P. The local RV surplus yard was a bit cheaper than Spruce, but still more than I was willing to spend on this project.
I did consider the UV affect on Coroplast. But the T'ailer won't be installed permanently on the car. It will be used on long trips that are in my future. (I am applying with Mission Aviation Fellowship in Nampa, ID. We are scheduled to go out there in January for Candidacy. There will be several trips to Nampa and back in the next couple years. And probably a bit of travel as we raise support before we leave for overseas.) The rest of the time it will probably be hung from the garage ceiling. The wife is already cringing at what it's gonna look like.

I ordered three sheets of dark blue Coroplast from my local sign shop. They charged me 17 bucks a sheet and had them the next day.

I'm impressed!

christofoo · 07-31-2012, 02:14 PM

You stole my idea.

Actually mine will be on a sedan, which will make it easier... but it's still going to be a couple of years before I get around to it.

I added a hitch receiver a few years ago to my civic to get a cargo rack in my slipstream, which had the benefit of having 0 impact on FE. Then I learned about boat tails and realized that's the next step.

Looking forward to seeing your results.

MetroMPG · 07-31-2012, 02:15 PM

OT: but, hey! I like your ecomodder.com decal application. Creative & looks good!

turbovr41991 · 07-31-2012, 09:32 PM

subscribed!