Mustang kammback help

[Floordford]

Can someone tell me if the profile of a 99-04 Mustang would benefit from a Kammback? I was thinking of trying some thing with Lexan or clear acrylic so its not too terribly noticeable. Im definitely not committed enough to try a boat tail. And if i tint the clear Kammback maybe people will think its some kind of louver thing.

[FastPlastic]

I don't see why it wouldn't improve some. If it's noticeable is going to be hard to say. Reminds me of the Ford Mustang Fastback which in 1979 had a Drag Coefficent of 0.02 lower than the standard model. Mind you that wing you have off the back is about the same angle and may already be giving the car some of the benefit a kammback would have.

[Floordford]

This is actually mine.





Its a far away shot so I just posted those two closer ones in the first post. It does have the curved spoiled and not the flat one that came on the 01-04. The only difference is that i moved it back from the stock location so it hangs off the end of the trunk. For reference, the more pixelated Mustang I posted has the curved wing in the stock location. But thats neither here nor there. The wing could go if it helps aerodynamics.

Another thing, I have no idea how people here are doing those layover shots with the ideal angle. So Im unsure how far or close my body is to being near that perfect curve.

[COcyclist]

Originally Posted by Floordford

Can someone tell me if the profile of a 99-04 Mustang would benefit from a Kammback? I was thinking of trying some thing with Lexan or clear acrylic so its not too terribly noticeable.

I would say "Hmmm... that depends". It depends on how well Ford designed the aerodynamics of the Mustang in the first place. It could end up being a lot of effort for minimal gain. The rear wing may actually be helping reduce drag. Have you read the thread about the "Flat Bonneville-type spoiler"?

http://ecomodder.com/forum/showthrea...ler-14946.html

IMO there may be other low hanging fruit such as grill blocking and folding or removing side mirrors that my make more of a difference in highway mileage. A belly pan is a nice stealth mod.

[California98Civic]

Originally Posted by COcyclist

I would say "Hmmm... that depends". It depends on how well Ford designed the aerodynamics of the Mustang in the first place. It could end up being a lot of effort for minimal gain. The rear wing may actually be helping reduce drag. Have you read the thread about the "Flat Bonneville-type spoiler"?

http://ecomodder.com/forum/showthrea...ler-14946.html

IMO there may be other low hanging fruit such as grill blocking and folding or removing side mirrors that my make more of a difference in highway mileage. A belly pan is a nice stealth mod.

I have now modeled three spoiler types, and tested two of them, with both tests discussed in the thread cocyclist recommends. First thing I would do based on what I have learned in the process is measure the angle from roof to spoiler top using a string. If it is in the vicinity of a 15* angle, build a Kamm from roof to spoiler. You might use the spoiler itself as a support or mount for a support. You might remove that spoiler. It likely produces drag for the sake of downforce.

I'm finishing a trunk lid project for testing, though I fully expect I might not use it in the end and go for a Kamm. Clear materials appeal to me also, because I want it to look fairly stealthy and I do not want to loose any more visibility than absolutely necessary. I also agree with COcyclist: the bottom of these cars is almost always an Aero mess so there is a stealthy way to improve your car's Cd. Lastly, look up "rear defusor" on this forum. You could use one--or an improvement over stock if you have one.

PS: nice looking car, man.

[cfg83]

Floordford -

I did this one to match what I think is the exact center of roof camber. You can see the streamline template slightly forward of the windshield :



Then I aligned the template with the windshield, which might be the *WRONG* thing to do :



Finally, I overlayed the slopes of the templates, bot only from the end of the roof to past the rear bumber :



From the above you can see that the slope in both cases is very close. In an ideal world you would design the kammback with the ability to slightly modify the sloping angle. In that situation you could "tune" the kammback with A-B-A testing.

CarloSW2

[winkosmosis]

The limit is 30 degrees, and the Mustang is within that limit, plus it has a gradual curve. I think it's fine the way it is. I'd be surprised if you got a significant improvement from making your beautiful car ugly.


Instead, get rid of the fake side air intake and give it an air dam.

[California98Civic]

Originally Posted by winkosmosis

The limit is 30 degrees, and the Mustang is within that limit, plus it has a gradual curve. I think it's fine the way it is. I'd be surprised if you got a significant improvement from making your beautiful car ugly.


Instead, get rid of the fake side air intake and give it an air dam.

My understanding from aerohead is that 30* is for the spoiler, but the rear window exceeding 22/23* is the max for attached flow, and that even that would need a longer lead-in curve than production cars can accomplish. The ideal is still about 15* from what I have seen (the "template" and the "Prius"). That's just my understanding, if I understood aerohead correctly. Winkosmosis, you think that's incorrect? But I agree on the side intake and the airdam, of course.

[winkosmosis]

Ooops... 30 degrees seems to be the worst angle, because airflow separates somewhere along the surface, instead of breaking at the top or staying attached

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[winkosmosis]

The Mustang's rear window is 22 degrees according to my measurement