> Do you have the actual Drag coefficients for the Series IV, V, and T=
iger
> MK1, MK1a, and MK2 ?
>
> There were slight differences in these especially in the grills, and
> mirror placements, and would be drastically different with the diffe=
rent
> top configurations. i.e. no top, Soft top , and Factory Hard top?
=97-?
-=97
> Rich
Guys,
My thoughts, for the day, on this subject. Concisely - "we do all the calculation we can, but there is NOTHING like a real test."
I don't know that our cars are can not just as well "guestimated" from si= milar designs where the numbers are available, such as the MGB, TR6, etc. They are all, generally, a little bit better than a piece of pl= ywood of the same frontal area. Those air dams help hold the car on the road better, and maybe improve air flow thru the radiator, but they don't affect the drag much. Thing is, the biggest influence on drag is the part your not looking at (although the top being up is a big help) and th= at is the "under carriage". This mess of lumps, bumps, pockets, beams, and rotating masses is the biggest contributor to drag of the car.= In the record cars (yes, even the prototype of my Jaguar XK120 ) had FULL belly pans, and full wheel covers (on the rear) and steel wheels= (not wire). Almost every record holder I know of does this, and nobody can drive them on the street. You think the Austin-Healy was bad?
Now there is one trick thing we can do, that ALL record holders know, and= that is to put a good coat of wax on the paint. This cuts the air resistance of what you do have down measurably. Besides, it looks faster = too.
We do extensive wind tunnel testing of our large space launch vehicles. W= e use the very best in wind tunnels, model building, and instrumentation. Your tax dollar costs are hardly considered. After the f= irst flight, the on-board accelerometers and the weights we measure before launch, "reconstruct" the actual trajectory, and back-calculate wh= at the drag (and therefore drag coefficient, must actually be. I can tell you now that the wind tunnel data wasn't very close. These factors have t= o be known very precisely to successfully put a payload of a given weight where you want it to be. So the NEXT one is a LOT better in predic= tion and results by updating that wind tunnel data with the real thing.
Same thing applies with the car. Measure the horsepower on a dyno, clock = your top speed, then back calculate what the drag must have been, considering your gearing. Now this "drag" includes all sources, including= tire flexing, bearing and gear losses, etc., but the wind resistance is, by far, the greatest contributor.
--
Steve Laifman < One first kiss, >
B9472289 < one first love, and >
< one first win, is all >
< you get in this life. >
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