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Old 09-15-2009, 01:44 AM   #21 (permalink)
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Originally Posted by 2000mc View Post
didnt they get down to a cd of like .20 or some awesomely low number?

the backside of those camaros looks pretty aero to me, especially thiers that looks like it has some rake to the whole car
I'm not necessarily saying they were incorrect with that statement, and yes, they got that camaro down close to .20 cd - but there was no real scientific testing laid out there...

IOW - Who knows what laying the windshield back would do on a car with a less aero profile? Who knows what mods were already in place on his car that might deaden the effect of the windshield mod? Who knows that there wasn't some improvement that was unnoticed because such a large cross section of the vehicle was changed?

They added foam core to the car to make the steeper angle, which means they had to add the foam from the upper ridge of the windshield (brow bar) to the hood line, somewhere that would make 60*. This would effectively make the nose of the car shorter. Does this have an effect on cd? Can you say for sure without really testing it? I can't!

Here's a fact: To properly "lay back" a windshield, you have to chop the top. That means a reduction in frontal area, as well as a smoother rake to the windshield line. NOW do you think it would have an aero effect?

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Old 09-15-2009, 03:39 AM   #22 (permalink)
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Originally Posted by alohaspirit View Post
its a good way to improve aero but imho that money would be better spent towards something else (perhaps a better aero shell for the metro)
Actually I don't think it's a good way to improve aero.

It probably isn't necessary.

As we know, most of the action is towards the rear.

As long as it's attached up to the point of max x-section area, that's pretty much all it takes to make the air happy (yeah gross simplification but whatever).

Then there's the weirdness of looking through a windshield that gives you the impression of driving from the back seat. And the solar gain. And maybe fogging (it's 3x bigger).

Quote:
but there was no real scientific testing laid out there...
are ya sure?

Quote:
Here's a fact: To properly "lay back" a windshield, you have to chop the top. That means a reduction in frontal area, as well as a smoother rake to the windshield line. NOW do you think it would have an aero effect?
now yer throwin other stuff in there, no fair.
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Old 09-15-2009, 07:09 AM   #23 (permalink)
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Haven't we had conversation here about distortion at extreme windshield angles?
Seems Basjoos has the same issue with his 'tail but it's less relevant in the rear...
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Old 09-15-2009, 05:24 PM   #24 (permalink)
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windshield

Quote:
Originally Posted by symmetr-yo View Post
I have been lurking for a while now...... and I am starting my journey for better fuel economy. I like the kammback which is going to be one of the first mods I am going do to a metro. Anyways If you had the cash would you get this type of windshield...... do not know if this has been addressed before .

There are GTP car windshields available from kit car manufactures for about $3,000 US.These seem to have the best aerodynamic attributes of any laminated safety glass ( a must in the USA ) windshield available at any price.This is on my shopping list for the Dodge D-100 project.To use this glass will require major surgery to the cab,something I'm will to do with the Dodge.--------- In the meantime,I have a rear windshield from a 1995 Camaro/Firebird which may find it's way into high speed air on the front of the T-100.---------- The EV-1 had a beautiful full wrap-around semispherical windshield,however,because of it's demise,we no longer have access to that speed/mpg equipment.What a loss!!!!!!!!!!!!!!!!!!
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Old 09-16-2009, 12:12 PM   #25 (permalink)
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Quote:
Originally Posted by JasonG View Post
Haven't we had conversation here about distortion at extreme windshield angles?
Seems Basjoos has the same issue with his 'tail but it's less relevant in the rear...
Isn't that only relevant with plexi or lexan? If you use real glass then I don't think that problem exists. If it did, then I wonder how you would see driving something like this:
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Old 09-18-2009, 11:43 AM   #26 (permalink)
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Funny things happen when light rays hit transparent media like glass or plastic at shallow (small) angles. In physics/optics this is known as the angle of refraction vs the angle of reflection, along with the "critical angle" where all light gets reflected rather than passing through the glass.

Here's a nice diagram to illustrate the phenomenon:

angle of incidence: angles of refraction and reflection on glass :: industrial glass -- Britannica Online Encyclopedia

This is not a perfect analogy, but pretty good: if you shoot a bullet at water at 90 degrees, it easily penetrates the water. If you shoot the bullet at the water at a very shallow angle, like five degrees, it will almost always "skip" and be "reflected" by the water. It can't penetrate the surface. Same deal with photons and glass/plastic. This turns out to have all kinds of repercussions for windshields and headlights with shallow/extreme angles of incidence.


I'm an optometrist, so this is a subject of some interest to me.

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Old 09-19-2009, 12:59 AM   #27 (permalink)
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The truck in the top picture is, I'm pretty sure, a screencap from the movie Tango and Cash.

Dumb movie. It did introduce the definition of the word "FUBAR" to everyone, however. So there's that.
Dang you! I saw that photo and was hoping to be the first person to ID that vehicle - I specifically recall Kurt Russell referring to it as an "RV from Hell"
... and that movie was hilarious! Awful, but good for enjoyment. Love the opening scene where Stallone shoots the gas tanker big-rig drivers...the truck stops magically and the drivers fly out of the windshield upon its final stop - totally unexplainable by physics but amusing.
Oh, and wasn't FUBAR in Full Metal Jacket before Tango & Cash? hmmm... time for some movie research for me!

Last edited by gascort; 09-19-2009 at 01:00 AM.. Reason: FUBAR
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Old 09-19-2009, 01:05 AM   #28 (permalink)
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Quote:
Originally Posted by gascort View Post
Dang you! I saw that photo and was hoping to be the first person to ID that vehicle - I specifically recall Kurt Russell referring to it as an "RV from Hell"
... and that movie was hilarious! Awful, but good for enjoyment. Love the opening scene where Stallone shoots the gas tanker big-rig drivers...the truck stops magically and the drivers fly out of the windshield upon its final stop - totally unexplainable by physics but amusing.
Oh, and wasn't FUBAR in Full Metal Jacket before Tango & Cash? hmmm... time for some movie research for me!
FMJ was a damn good movie.

And physics doesn't exist in Hollywood, man... The laws of existence are for mortals, not movie-stars.
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Old 09-20-2009, 09:13 PM   #29 (permalink)
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Dang you! I saw that photo and was hoping to be the first person to ID that vehicle...
Sigh, me too.
And stop raggin' on one of my favorite movies! Ha ha! Any movie with Teri Hatcher in it can't be that bad, can it?

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