Pontiac Aztek Kamm Back?

[vacationtime247]

Does the Pontiac Aztek have a kamm back design? Looks the part, but the angle seems off.

Just picked this one up for $1500. If for no other reason than that it was cheap and I'll make $.
VT247

[Frank Lee]

I've always wondered what the Cd on one of those is vs a comparable mini-van.

[vacationtime247]

Here are some side shots. Notice the roof rack delete at the bottom.
VT247

[shovel]

I really dig those cars, one of the most useful do-anything machines made - pity nobody could get used to their looks, I don't see anything wrong with how they look. In the public's eyes, coolness is inversely proportional to practicality.

[MetroMPG]

Seems somewhat steep to me - looks to be around 20 degrees near the end. Considering there's little to no plan taper, you're probably generating a decent pair of counter-rotating energy-sucking vortices off the outside trailing edges of that hatch.

You could tuft test it pretty easily to see what's going on.

[MetroMPG]

Did a Google Image search - there's an OEM spoiler that looks to raise/extend the trailing edge of the hatch, bringing the effective angle closer to ~15 degrees.

[aerohead]

I'm gonna try and post Kamm's 'templates' in a couple of weeks so everyone can see some his design evolution.
In 1955 he went from Stevens Institute down to Florida to consult on the design of a LeMans racer of Briggs Cunningham.
One of HOT ROD Magazine's road warriors was at Cunningham's at the same time and 'attended' Kamm's lecture on aerodynamics as he worked the clay.
Kamm was generally recommending a roofline of 10-degree slope,however when you see what he did for Cunningham you see that he broke his own 'rule.'
His last project was a Kamm-back modification to a 1960s DKW sedan which had a very conservative roofline and included his double,bifurcated,offset trailing edge roof fins.
I think he would say that the AZTEK roof was a little too fast and would have the vorticity that Darin has mentioned.
My guesses suck,but if you pinned me down,I'd think its Cd was in the neighborhood of 0.36.I would very much like to see a published figure.

[Sven7]

VT, why don't you tuft test it instead of speculating on the internet?

[cfg83]

vacationtime247 -

Here is a raw picture and and one with a template overlay :




CarloSW2

[vacationtime247]

Wow, that's not even close. But, just for kicks perhaps I'll have my wife record the back as her friend follows me with some tufts attached. It looked the part, but the angle is obviously way off.
VT247