Teardrop roof for boxy SUV?

[majestic]

Looking at their website, it looks like a number of companies signing on.







quite impressive

[Frank Lee]

I wonder why they don't simply put a taller cab air dam on, and increase the upper leading edge radius on the trailer?

Oh I see- this is a good marketing ploy to stand apart from the rest.

[FastPlastic]

So I know the topic has strayed a bit, but the thread reminded me about a photo I took a while back. After getting about 2" of snow, being the lazy man that I am, I cleaned the windows off and headed off to work. Top speed of about 35MPH for about 2 miles got me this on the roof. It's a bit hard to make out, but was fairly smooth up top.

[XJguy]

Originally Posted by aerohead

My opinion would be to leave the roof as is,and go after the wake.I'm going to try and give you a link.It's a photo of a Rabbit with a similar roofline and completely attached flow,and then you'll see the enormous wake that's robbing you at the gas pump.-------------------------------------------------------- Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - 's Albums

MODERATOR EDIT: Added by cfg83 :

Good comparo. The Jeep Cherokee's design was in part influenced by that car.

[XJguy]

Originally Posted by winkosmosis

I wonder if they made the roof like that for aerodynamic reasons.

I do remember reading that more and more cars are getting arched roofs for aerodynamics, but I guess the question is whether you reduce total drag by adding an arch to an already flat roof and increasing frontal area

Many of these "aero" designs being implemented are just to give the consensus that they are more aerodynamic to the general public when in fact they are less so. Case in point, the Hybrid versions of the full size GM SUVs actually use sharper angled components than the regular models to promote sharp separation of flow. Another example the late model year F-bodies, although much more swoopy than the model they replaced are actually far less aerodynamic that the chiseled model of the late 80s.

Those rounded roofs may actually be causing more lift, hence more drag...but they look aerodynamic so the buyer thinks it is...and is more eager to get rid of his flat roofed SUV/wagon for a new one.

[XJguy]

You want to improve aerodynamics on an XJ, do as others have suggested, work on minimizing wake or promoting a clean break.

Prevent or minimize airflow into wheel wells, provide high pressure air evacuation.

Decrease the sharp transition from hood to wind sheild.

More aerodynamic side view mirrors.

More aerodynamic fender flares.

Provide through the hood air evacuation for radiators.

Smooth underbody if you keep current ride height OR lower body and install airdam as low to ground as possible to prevent air from going under Jeep.

Low drag wheels or wheel covers. Ford wheels are of the same bolt pattern and often same back spacing.

[winkosmosis]

I noticed a UPS truck today with an arched roof. I forgot to take a pic but it looked like this, except I think the arch was taller.

[Cd]

Whatever became of this idea for the Jeep ?

Im curious to see it tested .

If it does anything but damage, you could even use it to store something in.

[KamperBob]

Originally Posted by FastPlastic

So I know the topic has strayed a bit, but the thread reminded me about a photo I took a while back. After getting about 2" of snow, being the lazy man that I am, I cleaned the windows off and headed off to work. Top speed of about 35MPH for about 2 miles got me this on the roof. It's a bit hard to make out, but was fairly smooth up top.

I just stumbled on this thread over morning coffee. On page one I started thinking a snow carving might indicate bow splash from the windshield over the roof leading edge. A couple pages later I saw this. Excellent!

[Sven7]

Originally Posted by winkosmosis

That is interesting. I guess the only way to know would be to tuft test, but that would require mounting a camera on a stalk to see the roof

I would still like to see some "before" tuft test results on this.