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trikkonceptz 05-30-2008 06:16 PM

Vibe Kammback / Boat tail
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I started this thread to not thread jack the CRX one but I too an heading down the road of heavy body modification. Not because its practical, but because I can.

My question though is;

Rather than building a full boat tail, what benefit / drawback will I see by building a proper Kammback and partial rea bumper boat tail?

Here is a profile pic of the Vibe, mind you it will go one of two ways;
-The way it is with a kammback and partial rear bumper boat tail
-Or sloped roofline with partial bumper boat tail.

aerohead 05-30-2008 07:19 PM

Vibe Kamm back / boat-tail
trikkonceptz, good question.And your in luck,as you already have the Kamm-back.GM and Toyota have done a really good job on the Matrix/Vibe aero and you should have clean,fully attached flow,up to where your Vibe ends.This was the whole point behind Kamm's work.And with the wagon-back body style you get to steer around C-pillar vortices which I must be careful about with my fastback.And even better for you,is that the body of the Vibe/Matrix begins plan-taper contraction quite a bit forward along it's length,adding pressure along the sides and also top,as the top is also carefully sloping downward as well. All of this means that you can have more aggressive sloping on the tail.So for you,the decision is,how long do you want to make it? If you merely follow the natural progression of the Vibes contours,you'll get a beautiful converging boat-tail and you can chop it off wherever you like ( truncating ).The further back you go,the steeper the slope can be.I posted a thread about the Gentoo Penguin with Cd 0.07 at GOOGLE Images,page 3,showing a single penguin swimming underwater.That's your boat-tail.And a parting thought,as this place is going to close down at 5:30. In the picture of the Mercedes-Benz C-111,they used 28-inches of boat-tail,and it dropped the Cd from 0.2378,to 0.195.Had Mercedes gone ahead and used the full length ( 60-inches ) the Cd would have dropped to 0.178 ( another 25 % drop! ) and the car would have beat it's own record.Consider some concession on length,as you've got to be able to park that thing,and you don't want to knock pedestrians over when you round a corner.If you want to go really crazy like me,consider a very light streamliner trailer for extended highway travel,that would plug into a receiver hitch.It could cut drag to bare minimum on the open road,then you could yank it for daily commuting.Compromise sucks but somehow reality has intruded into my imaginary drag-free world,and even I have had to make some compromises to survive in traffic.Keep us posted,good luck,Phil

cfg83 05-30-2008 07:23 PM

trikkonceptz -

I did this for fun (I am a Vibe fan) :

Don't know if it would work. Just looks cool to me.


trikkonceptz 05-30-2008 07:49 PM

^^^ Your pictures is exactly where I am heading within the next 60 days ...

But I wanted to start a partial boat tail also coming up from the bumper in order to extend the Kammback a little more .... HOWEVER ....

The idea of building a trailer to slip stream the rear is AWESOME !!! I can use it on my work commute daily 55 miles each way all hwy, and disconnect it for city driving where my speeds are always 40mph or less ...

Is that trailer theory theoretical or actual? Because otherwise I'm going to harbor frieght this weekend and buying a very light small utility trailer and getting to work .. LOL

Laterz ...

whokilledthejams 05-30-2008 11:37 PM


Might I suggest finding/building a single-wheel trailer? They use two hitches, so it only pivots vertically, rather than horizontally. Hypothetically, one wouldn't need as much clearance as with a conventional trailer. I've looked into it myself, and it's something that I think would take more fabrication resources than I currently have at my disposal, but it's an option that I just don't think many people are aware of.

Here's a fairly informative site about vintage single wheelers:

Further googling comes up with several companies that make modern single wheel platform trailers that could be adapted with varying degrees of difficulty.

Still, it would probably be easiest to simply build a small one, perhaps similar to this teardrop:

Needless to say, a small teardrop trailer appeals to me, because I'm too vain for a Kammback/boattail on a car I'm still paying for. Just my $.02, is all.

MetroMPG 05-31-2008 12:04 AM

The trailer idea isn't theoretical - aerohead built and tested a 1-wheel aerotrailer on his CRX.

Whokilledthejams - your Scion would be an ideal vehicle for a tapered trailer too. Welcome to the forum, by the way.

whokilledthejams 05-31-2008 12:13 AM


Originally Posted by MetroMPG (Post 29893)
The trailer idea isn't theoretical - aerohead built and tested a 1-wheel aerotrailer on his CRX.

Whokilledthejams - your Scion would be an ideal vehicle for a tapered trailer too. Welcome to the forum, by the way.

Thanks. I'm not the least bit surprised someone's built an aero single wheeler already, actually. It's definitely something for me to look into in the future (not that cargo capacity is an issue for me).

trikkonceptz 05-31-2008 12:23 AM

DAM .. the idea keeps getting better, and I do have the resources to get it done, even building one from scratch. If I can muster up some extra cash after my trip to tulsa next week I'll build it and I promise, once it works I will make it available to those vehicles I have access to (Scion xB's hint hint) for a very reasonable price, meaning costs, cuz this stuff is to fun ...

beluga 01-19-2014 02:57 AM


deejaaa 01-19-2014 10:59 AM

someone('s idea) died.

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