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Old 03-13-2010, 03:58 PM   #40 (permalink)
aerohead
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numbers

Quote:
Originally Posted by orange4boy View Post
Oh, I agree. I realize that a lot of these cars were aerodynamic styling exercises that's why I titled the thread "Aero Beauty and innovation" and not Aero, Beauty and Innovation"

I also did not make any claims as to these car's Cds, low, high or otherwise. The first sentence in the thread was meant to convey that I was discovering the aerodynamic aspects and technical innovations of Bugatti cars.

I didn't even attempt to make guesses as to their Cds as these would prove to be totally unreliable.

I'm still looking for Cd and frontal area numbers but haven't found any.
I've never run across any quanta for these cars,although GOOGLE never ceases to amaze,so perhaps at some point we may get some hard numbers.
Hucho did make a comment with respect to the 'tank' in his 2nd edition,and wrote that he believed the car would probably suffer separation in the area where the windscreen would typically be and never recover.
I've been spending time with Jaray's development model and I am convinced that even in separated flow,the aft-body still performs a beneficial function.
Without a technical term to draw on,I'm refering to it as 'stuffing the wake.'
And it's a concept aerodynamacists stumbled onto when testing convertibles with the top down.
By placing manikins in the open car they were able to measure lower drag do to this 'stuffing,' and I think that the aft-body of the Bugatti 'tank' is helping to perform this function.
All,except the last of Jaray's models( the full-tail) suffer separated flow very early on the body but do not suffer the drag as would occur at the same point for a Kamm chop,so the tail must serve drag reduction even though it's less than ideal.I believe it's true of all pseudo-fast-back cars.
I'm going to look at R.G.S.White's 'Method of Estimating Drag Coefficients' at some point,'n see if it might offer some insight into the early cars.
The main working page from it is in the Phil Knox Aerodynamic Photos Album somewhere.
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