CARGaerO t'ailer; a hitch-mounted boat tail (Pontiac Vibe)
 

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.
http://i337.photobucket.com/albums/n...tchcarrier.jpg
http://i337.photobucket.com/albums/n...a/100_7015.jpg

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.
http://i337.photobucket.com/albums/n...a/100_2379.jpg

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...
http://i337.photobucket.com/albums/n...narysketch.jpg

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

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.
http://i337.photobucket.com/albums/n...ansideview.jpg

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.

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

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

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.

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

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.

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).

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. :thumbup:

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. :rolleyes:

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. :cool: I'm impressed!

http://i337.photobucket.com/albums/n...ia/blucoro.jpg

You stole my idea. :mad:

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.

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

subscribed!

If you don't have it done by the time I get there, I'll be happy to lend a couple fairly skilled hands:thumbup:. Don't worry, I only "Red-neck" my own stuff:D.

Great idea!!

Ha! Thanks! Yeah, I thought it kinda gave it that "race car sponsor" look. :)

Thanks, Jethro. I do hope to have the tail done by then, though. That's my motivation. The pictures of THREE boat-tailed cars together in one place are gonna be epic!
Couldn't get to it last night, as a friend needed help with a brake job. I hope to hit it pretty hard on Friday, though. It'll be my last 'free' Friday before I start a new job next week.

I'm getting a little nervous about storing the thing. I had a thought of making it so it would fold or disassemble, but I don't have the time or engineering ability to do that. It may be too bulky to hang from the garage ceiling. I may just have to lay it against the house in the backyard and throw a tarp over it. I know you all would say "just leave it on the car!" but I know the wife won't go for that. I've already promised her that it's only for long trips.

I sympathize. Lack of storage led to this ultimate fate of my Firefly's prototype boat tail:

http://ecomodder.com/forum/attachmen...1&d=1294593814

Though mine was mostly cardboard. :)

Ugh, I think we all whimpered when you did that. :o
The 15% you got is still just incredible to me. I'm hoping beyond hope that I might get 10%. *fingers crossed*

After lugging my toolbox to the new job this morning, I got around to working on the t'ailer. As is typical, I didn't get quite as far as I hoped. :snail:
On the plus side, I still have tomorrow yet. :thumbup:

http://i337.photobucket.com/albums/n...a/100_3007.jpg

I pieced together leftover black coroplast for the forward bulkhead. I'm using Duro super glue. It works pretty good. decent peel strength, and really good sheer strength on the lap joints. I've temporarily taped dowel rods onto the face of the forward bulkhead to keep it somewhat rigid until I install the skin.

thats coming along nicely!!

On Saturday, I was only able to get the diffuser attached. My wife is a wonderful woman and is generally tolerant of my modding projects, but she sees an open schedule like VanGough eyes a blank canvas. So I had to clean up a bit earlier than I had planned.
Getting the lower surface attached, even if it is only with screws semi-permanently, has gone a long way towards stiffening up the structure and keeping the rear bulkhead centered.

Great progress :)

If you do not have it done by sept 3rd I can come a day early and help.

What are your plans for MAF? Our family helps supports several missionary's and we know of MAF quit well. One of my brothers looked into serving there, but God did not lead him in that direction.

It sounds like our meet up will be fun :)

Thanks, WS! I appreciate the offer. We'll see how it goes.
I am applying with MAF as a Maintenance Specialist. In January we go out to Nampa for "candidacy", which is when we learn where we will be stationed. It could be Haiti, Africa, Indonesia, or WhoKnowsWhere. Exciting stuff. We'll still be in the U.S. for a year or two, going through training, etc.

Worked on the t'ailer a bit. I finalized the attachment of the diffuser section, and scored the coroplast between the flutes to allow it to curve up around the lower aft bulkhead. I had a roll of aluminum flashing laying around (the stuff MetroMPG mentioned earlier), so I cut a piece of that for an exhaust deflector. It's not real pretty, but it's underneath and out of sight. I guess it turned out OK considering I shaped it with my bare hands, the edge of the workbench, and a framing hammer! :o

http://i337.photobucket.com/albums/n...austshield.jpg

The rear bulkhead was a bit floppy, so I screwed on a frame of aluminum angle to hold it flat. This will be the outer edge of the access opening.

http://i337.photobucket.com/albums/n...kheadframe.jpg

It doesn't LOOK like much progress, but it's necessary stuff that is easier to do now with full access. Once the sides go on, access to some areas will be more difficult.

Good job!

The exhaust deflector looks 90% the same as mine.

what are your plans for sealing it to the car to keep air from sipping in at the bottom and trying to push the tail off?

Not planning on any sealing per se. Just going to keep it as close to the car as I can. The diffuser's front edge is pretty close to the lower surface of the bumper. I don't think there's a lot of high-speed airflow there, as it's right behind the rear axle and muffler. Take a look at it come Labor Day and tell me what you think.

I'm planning to eventually install a rear belly pan which will help air flow transition onto the boat tail.
But it won't happen before Labor Day.

the belly pan is a good idea.

Do you have a good place for tuft testing? It could be a fun thing to do will all our tails. they we can all compare notes and help each other make their cars better.

awesome progress! I keep looking at my tow hitch wanting to start something...

do it do it do it

I'm toying with the idea of a helmet cam. As a chase bike I could record video of tufts on the road. Being smaller I'm thinking less "hand on the scale" effect in terms of adjacent lane proximity and possible interactions between vehicles skewing up data. Thoughts?

but a bike is aero dirty, it leaves a big wake.

Like WS urges, just do it! I've been looking at my hitch and luggage carrier forever. Just gotta take the leap.

Yeah, sure do! There's a several mile stretch of four-lane less than a mile from the house. There's a stoplight in the middle of it, but with a little luck you can catch it green.

KamperBob; I like that idea. If you stayed way over by the white line and trailed behind the test vehicle a bit, it should work fine, I think. Want to meet up with JethroBodine, Weather Spotter and I on labor day? :D

Any good places to do coast down tests? back roads with no traffic are needed. with two matrix family cars with tails I want to see the difference.

Is yours a manual or auto?

we could even swap tires and run ABA on each others car to see how LRR tires help us.

my nose cone might even fit your car :)

Alright, alright. First were comparing "tails", now were taking about trying on each others "shoes" and "tops"...? What are we, 15 year old girls?(Come on, you were all thinking it:D!)

Seriously,

Bob- I'd be happier if the passenger had the helmet cam on as the driver might want to keep his/her head pointing more toward the direction of travel instead of trying to stare at the rear wheel tufts while riding directly beside the object car;).

I'm up for tufting and coast down. I'm thinking of going 5-600 miles on the first day so that I can get to your place fairly early to get the serious stuff done before the serious adult beverages start happening:thumbup:.

Fair point. In a relative sense. Higher Cd. Much lower CdA though.

Safety first. Absolutely! I like to float ideas early for feedback. :)

Yeah, plenty of backroads around here.
It's a manual.
She's got Nokian enTYRE 205/55 R16's on her. What's on yours?


Ha ha! Shoes and tops. That's funny. I can't speak for Weather Spotter, but your adult beverages might be enjoyed only by yourself. I'll join you with a Mt. Dew, though. :D

Ha! Pepsi it is:cool:. That just means we have more time for testing:D.

How about this as a basis for a hitch-mounted boattail :
SMV Space Extender

The different versions :
SMV Space Extender

It's a trailer with castoring wheels - so no issues with parking & turning as the trailer is fixed along the length axis.

It'd swing out though.

ive read through most of the trailor hitch threads... makes me want to get a hitch put on the fiesta sedan! i would gain storage/carrying capacity instead of incorporating an empty(useless shell) tail to my boot lid!

do it :)

euromodder:
It looks like an option, I can only read English so all I can do is look at the pics.

I will bring myself some sweet tea for our drinking around the fire pit. We would not want Hydro Jim to be scared off since his is under the legal age for adult beverages :)

Tango, do have any marshmallows :D

My tires are LLR Bridgestone Ecopia 205-55-16

spaceextender
 

It would be cool to see a tail adapted onto it.It looks rugged.

WeatherSpotter = Ecomodder's boat tail enabler:D:thumbup:.

"Boat tail enabler" ha! That's great. 'Yah, just doooooo eeeeet!' :p

Today I wrapped the lower 'diffuser' up around the aft corners and secured it with super-glued straps of coro.

http://i337.photobucket.com/albums/n...a/100_3018.jpg

The rear bulkhead looked too tall to allow the degree of taper I want, so after some measuring and marking, I cut it down several inches. The following pic is of "before". If you look closely, you can see my initial cut.

http://i337.photobucket.com/albums/n...a/100_3012.jpg

This led to cutting two "stringers" that will hold the top skin at the desired taper/curvature. I leveled a piece of coro on top of a garbage can and used a leftover pipe insulation noodle to mark a curve. A stick of wood trim would've been more elegant, but this is what I could scrounge up!

http://i337.photobucket.com/albums/n...a/100_3010.jpg

After getting it marked, I cut out two stringers and installed them like this;

http://i337.photobucket.com/albums/n...a/100_3015.jpg

Again, slow going, but I think it will progress quicker when I'm installing the skin. Initially I was thinking of wrapping the skin in four sections; top, bottom, and two sides. But the thought of attaching the sides single-handed has been daunting. So I've decided to do them in two separate pieces per side. I think that will allow me to make better progress next weekend. It will also allow me to follow the body line in the Vibe's rear fender.