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  #41 (permalink)  
Old 03-22-2012, 08:27 AM
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Dwight, if I read that info correctly a Cobra takes less hp than a ZR1 Vette to go the same speed. That doesn't seem plausable to me, especially without removing the windshield.

Last edited by twin turbo; 03-22-2012 at 08:36 AM..
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  #42 (permalink)  
Old 03-22-2012, 11:51 AM
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Quote:
Originally Posted by patrickt View Post
Most people would bet that a Lamborghini Countach would not have the same CoD as the Cobra, when actually they're very, very close.

Perhaps its those wiide tires.
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  #43 (permalink)  
Old 03-22-2012, 12:07 PM
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Quote:
Originally Posted by Dwight View Post
So I am going to use a published Cd of 0.42 for the open bodied Cobra
That's most probably too low, ~0.6 is what I remember. Especially since Dominiks coast down test with the hardtop in place confirms this number, I'd guess it would be higher without the hardtop.

It should be a save approach to use 0.65 for the Cobra.

Would be interesting to know what effect using the small comp windscreen does have on the cd.

Simon

Last edited by CobraV8; 03-22-2012 at 12:10 PM..
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  #44 (permalink)  
Old 03-23-2012, 05:35 AM
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Quote:
Originally Posted by Dominik View Post
Incidentally the photo taken from my car IS outside the OPEL mother plant.
Tire friction losses are a major factor at higher speeds, even with 500cui+ ;-)
Okay MASONRY!!! thank you I'm sure there were some that could not figure out what I meant with that spelling error.
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  #45 (permalink)  
Old 03-23-2012, 08:04 AM
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so do you have to be a mason to go fast??
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  #46 (permalink)  
Old 03-23-2012, 01:30 PM
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Every chisler I knew was able to get out of Dodge really fast.
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  #47 (permalink)  
Old 03-24-2012, 07:42 AM
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Quote:
Originally Posted by Jerry Clayton View Post
so do you have to be a mason to go fast??
Heck one of the guys I ride with is a Mortician and he is plenty fast.I have worked with stone and mortar riding around in my brick sure brings out the racer.
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Old 03-29-2012, 02:06 AM
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"out of Dodge really fast."

Like: dodging it?
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  #49 (permalink)  
Old 03-31-2012, 08:37 PM
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To Dwight who posted on March 22: I didn't study in detail all your equations because when I got to "rho" (air density) in "slugs", I lost interest. A slug is a unit of mass; density has units of mass per cubic ft. I'm surprised you didn't give frontal area in pounds. Suggest you go back to Cal Poly and take a refresher course.
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Old 03-31-2012, 08:46 PM
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I guess that in your in depth reading and analis of the article that you missed the fact that it wasn't Dwight , but a guy named Mayfield that authored that?????
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  #51 (permalink)  
Old 04-01-2012, 06:58 AM
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sorry jon@harrison this is not my calculations. I copied it from (I think) someone on the FFR site several years ago.

This type of math is way beyond my abilities.

Thanks for the compliment though.
I could not get the charts to copy paste correctly, sorry.

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  #52 (permalink)  
Old 04-01-2012, 07:19 AM
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I wanted to post the charts from the article but could not. I did a google search and found that L.E. Mayfield wrote the tech article. He is big into a Sunbeam Tiger project. Interesting reading.
The first link is to the article on Cobra. The other two are to his Home Page and analyses page.
Interesting reading but I'm not smart enough to argue with anyone about this stuff.
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"Cobra HP vs Speed" Wanna know how fast your FF Cobra replica or real thing will go if you have a certain amount of horsepower? Well here is everything you want to know. Rest easy when you get to the page and scroll down to the table and chart!

The Mayfield Company Homepage - Automotive Analyses

The Mayfield Company Homepage - Automotive Analyses

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  #53 (permalink)  
Old 04-01-2012, 09:15 AM
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The Mayfield Company Homepage - Automotive Analyses

I believe he addresses the concern for mis-matched units of meaure when he substitutes R - the universal gas equation - for the former unit of measure, slug.
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  #54 (permalink)  
Old 03-22-2016, 10:02 AM
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Quote:
Originally Posted by Excaliber View Post
Oh I'm just jumping up and down over the good news...
No cause for celebration. The 99-2003 Ford Lightnings come in at 0.36. So definitely not more aerodynamic than all trucks.
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Old 03-22-2016, 02:15 PM
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Blister,
What year is it where you are? It's 2016 over here.
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  #56 (permalink)  
Old 03-22-2016, 02:18 PM
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Quote:
Originally Posted by jon@harrison.ne View Post
The drag coefficient Cd has nothing to do with the size of the car,only the shape. The total drag force is proportional to the frontal area times Cd times speed squared.
Isn't is proportional to speed cubed?
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  #57 (permalink)  
Old 03-22-2016, 02:28 PM
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Drag force is proportional to speed squared.

Drag power is proportional to speed cubed.
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  #58 (permalink)  
Old 03-23-2016, 05:08 AM
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It matters very little to this cat what that number is. I love my masonary 4 wheel hot rod.
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  #59 (permalink)  
Old 03-23-2016, 07:02 AM
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Unless you plan on racing at LeMans or at the pro level in SCCA, none of us are ever going to attain speeds at which the drag coefficient becomes meaningful. But it does make for an enlightening discussion while we sit at home and complain about the lousy weather that prevents us from driving our cobras....
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Old 03-23-2016, 12:49 PM
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Quote:
Originally Posted by eschaider View Post
Ole Pete was one sharp dude. He actually did a great deal of personal research into airflow and clean automotive design before he implemented it in the real world we know as the Daytona Cobra.
....not was, he is pretty sharp. On top of that, he is a great person!


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