pickups and even a Scion more aerodynamic than Solstice! - Pontiac Solstice Forum
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post #1 of 100 (permalink) Old 02-10-2008, 08:12 AM Thread Starter
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pickups and even a Scion more aerodynamic than Solstice!


Drag coefficient: .35


Drag coefficient (with top up): .45

How is it that something that looks so sleek can have one of the worst drag coefficients on record: as bad as an average pickup truck, while a brick on wheels (Scion) does appreciably better? I know aerodynamics is an art and looks can be deceiving, but c'mon! A Scion having a better drag coefficient than the Solstice with the top up? Something doesn't add up. Any idea why the Solstice has a .45 drag coefficient? It certainly defies "prediction" by looking at the car.

Mike
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post #2 of 100 (permalink) Old 02-10-2008, 08:24 AM
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Aerodynamics is a science, not an art, and looks are pretty much worthless in predicting a shape's drag coefficient. Square backed objects, unless the taper is very long, are generally more efficient than steeply tapered objects. The long hood on the Kappas generates a rising pressure gradient that creates a lot of turbulence when it reaches the windshield.

If you want to see where the drag comes from, look in your mirrors while driving in the rain, or on a wet road. The size of the water plume that follows the car is a solid indication of drag producing turbulence.

Keep in mind that drag is a product of drag coefficient and cross sectional area.

Where did you get the Cd numbers ?

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post #3 of 100 (permalink) Old 02-10-2008, 08:42 AM Thread Starter
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Originally Posted by JRinKY View Post
Where did you get the Cd numbers ?
Just Google Solstice drag coefficient. .45 (or .44) is listed in several reviews as is the .35 for the can of corned beef on wheels (Scion).

Mike
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post #4 of 100 (permalink) Old 02-10-2008, 08:58 AM
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Finally an explanation for why our fuel efficency is so much worse than I would have expected for such a small car! Was wondering how that could be.
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post #5 of 100 (permalink) Old 02-10-2008, 09:13 AM
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A little more googling shows drag coefficients for the MX5 is .38, the Z4 is .35, 350z roadster is .34, and the Boxster is .31. All approximate as the reported drag coefficients varied somewhat from source to source.

I for one am glad that GM designed the Solstice as a beautiful car without slavishly letting a wind-tunnel dictate the car's shape, like all other manufacturers do. All of the other cars are more bland in shape, less coke bottle shaped, less sculpted detailing.

Most cars get the wind-tunnel treatment and you end up with a bland, lifeless design like the horrible G6. I'm guessing the Camaro is not exactly going to be a slippery eel either. The Mustang has a Cd of .38, but while it has the old Mustangs shape, all detailing is removed and all edges have been melted to bow down to the wind tunnel.

Why is the Sol a brick? I know not, so I will buy JRinKYs explanation, although the Z4 also has a long hood, yet a low Cd. Just food for thought.

Oh, and look for future Solstii and ALL cars to be even more bland in the future to meet that ridiculous 35 mpg CAFE standard. If you thought cars were bland and similar looking in the past, just wait until 2020. All cars will take on the same non-descript aerodynamic styling with no detailing whatsoever.

Just people movers. Keep your Solstice, Camaro and Challenger forever. The short-lived renaissance of automotive design is dead. Thank you CAFE. Thank you idiot government politicians.

I guess as long as the Solstice is a frame-off car, maybe some kit-car company will make some interesting body panels. I'm not holding my breath. The next gen Solstice is going to be unibody to save weight, at the expense of chassis rigidity.

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post #6 of 100 (permalink) Old 02-10-2008, 10:25 AM Thread Starter
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Originally Posted by jimbo View Post
I for one am glad that GM designed the Solstice as a beautiful car without slavishly letting a wind-tunnel dictate the car's shape, like all other manufacturers do. All of the other cars are more bland in shape, less coke bottle shaped, less sculpted detailing.
Couldn't agree with you more, although I do think the engineers could have done a few things that didn't affect the overall appearance of the car that might have been able to reduce the drag coefficient to at least below .40. Just seems strange that a car that looks as sleek and flowing as the Solstice should pull a drag coefficient worse than just about every car on the planet, and as bad as an old-style pickup truck. It's one reason the top speed on these things is only 142. If it had a drag coefficient of under .40, I bet it'd hit 150 or more. So some of it is about performance/function and not just looks.

Mike
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post #7 of 100 (permalink) Old 02-10-2008, 11:27 AM
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Hmmm,
You'd have a hard time convincing me that my Solstice has more drag than my Ram.
Numbers, I'm sure, don't lie. I'll take my sleek Solstice getting 25-35mpg (Hahn turbo)
over my gas guzzling Ram any day, and I do plan to hold on to it for a long time while the rest of the world goes "vanilla."
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post #8 of 100 (permalink) Old 02-10-2008, 11:36 AM
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Let's see this horrible as you all put it drag coeficient roadster beat ALL comers on T2 SCCA racing by a very wide marging.
That includes all the cars Jimbo posted. "MX5 is .38, the Z4 is .35, 350z roadster is .34, and the Boxster is .31."

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post #9 of 100 (permalink) Old 02-10-2008, 11:50 AM
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where are the downforce equations here? DC is not relative without a DF equation.
What are the totals once lowered? I bet they become much more effecient. Who knows and who cares?

The comparison against an xB is laughable. Put the players against each other in a challenge and post results.

Hey! I still dig this car!
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post #10 of 100 (permalink) Old 02-10-2008, 01:07 PM
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Quote:
Originally Posted by mikeysolstice View Post
Couldn't agree with you more, although I do think the engineers could have done a few things that didn't affect the overall appearance of the car that might have been able to reduce the drag coefficient to at least below .40. Just seems strange that a car that looks as sleek and flowing as the Solstice should pull a drag coefficient worse than just about every car on the planet, and as bad as an old-style pickup truck. It's one reason the top speed on these things is only 142. If it had a drag coefficient of under .40, I bet it'd hit 150 or more. So some of it is about performance/function and not just looks.

Mike
Of course I agree with you...

This car was like the Chevy Volt, form before function. The Volt concept is also as aerodynamic as a brick. That is why the Volt won' t look anything like the Volt concept. Electric cars have to be slippery.

Point is, both cars were designed to look good with little or no wind tunnel testing. When Lutz said "build it", there wasn't any way to go back to the drawing board to make the Solstice more slippery.

Cd isn't everything. Swept area is important to. Pushing more air despite lower drag could actually yield more air resistance than a car with more drag that puts a smaller hole in the air.

Still, your point is valid. And don't forget how wide the Solstice is. That adds a lot more frontal area than say, a Miata.

I'm sure Solstice II will be more aero friendly. But will it be as gorgeous? I would hate to see Solstice II squashed into the Vette's shape just to meet the Vette's .28 Cd.

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post #11 of 100 (permalink) Old 02-10-2008, 01:15 PM
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Quote:
Originally Posted by Yonnie View Post
Hmmm,
You'd have a hard time convincing me that my Solstice has more drag than my Ram.
Numbers, I'm sure, don't lie. I'll take my sleek Solstice getting 25-35mpg (Hahn turbo)
over my gas guzzling Ram any day, and I do plan to hold on to it for a long time while the rest of the world goes "vanilla."
Cd is just how efficient the car flows through air. Your Ram is a lot bigger and punches a bigger hole in the air. The CdA is the important factor, Cd x frontal area.

It is likely that your Ram has a much larger CdA than the Solstice.

You can't measure Cd with fuel economy. Your Ram weighs a LOT more than your solstice. Mass and resistance both affect fuel economy. Resistance only matters at high speeds. Mass ALWAYS matters.

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post #12 of 100 (permalink) Old 02-10-2008, 01:21 PM
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Originally Posted by LatinVenom View Post
Let's see this horrible as you all put it drag coeficient roadster beat ALL comers on T2 SCCA racing by a very wide marging.
That includes all the cars Jimbo posted. "MX5 is .38, the Z4 is .35, 350z roadster is .34, and the Boxster is .31."
Irrelevant measure.

The Porsche 911 has a Cd of .27. The Ford Mustang has a Cd of .37. Mustangs beat them handily in Grand Am racing, because the Mustangs were allowed an unfair advantage in horsepower their first year. The racing success of Mustangs didn't mean anything for Cd either way.

Same for the Solstice GXPs in T2. Next year they will have to wear extra weight or won't be able to tweak turbos.

Cd is ONLY one factor in racing. It really helps. All things being equal, a race car with a lower Cd will beat one with higher Cd. But all is not equal from driver skill, to suspension design, to tire choice, to car's overall weight, to team ownership.

Having Don Knowles drive your car is like having a car 10% lighter with 10% more power and 10% better Cd. Driver skill counts for a LOT.

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post #13 of 100 (permalink) Old 02-10-2008, 01:34 PM
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[QUOTE=mikeysolstice;641404]
Drag coefficient: .35


Drag coefficient (with top up): .45

How is it that something that looks so sleek can have one of the worst drag coefficients on record: as bad as an average pickup truck, while a brick on wheels (Scion) does appreciably better? I know aerodynamics is an art and looks can be deceiving, but c'mon! A Scion having a better drag coefficient than the Solstice with the top up? Something doesn't add up. Any idea why the Solstice has a .45 drag coefficient? It certainly defies "prediction" by looking at the car.

Mike[/QUOTE




Find out what they're smoking so we can avoid it.

Last edited by SCISOLSTICE; 02-11-2008 at 01:35 PM.
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post #14 of 100 (permalink) Old 02-10-2008, 02:06 PM
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Originally Posted by jimbo View Post
Most cars get the wind-tunnel treatment and you end up with a bland, lifeless design like the horrible G6.
Yep, classic argument about beautiful styling not giving up to bloody aerodynamics.
Same excuse for clumsy packaging, weak structure, excessive weight, mediocre performance,
dubious ergonomics, excessive NVH, lousy fuel economy, cumbersome maintenance, high price, etc, etc.

Sure, it is easier to design that way. Kids can do that, and it looks cool, dude!

Screw those idiotic aerodynamics! If only the screamin’ chicken could make it back.
Now that’s THE STYLE, man…
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post #15 of 100 (permalink) Old 02-10-2008, 02:17 PM
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Quote:
Originally Posted by mikeysolstice View Post
Couldn't agree with you more, although I do think the engineers could have done a few things that didn't affect the overall appearance of the car that might have been able to reduce the drag coefficient to at least below .40. Just seems strange that a car that looks as sleek and flowing as the Solstice should pull a drag coefficient worse than just about every car on the planet, and as bad as an old-style pickup truck. It's one reason the top speed on these things is only 142. If it had a drag coefficient of under .40, I bet it'd hit 150 or more. So some of it is about performance/function and not just looks.

Mike
Only a 142 ? Really ? K if u say so
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