Best Wind tunnel I have ever seen for the Poor Man was Muroc Dry Lake...
I hated the Dust until I got home and clean and watched a Video tape of the
event Cris Shear sent me.... I was tickled to see how low the Dust trail
on the Camaro was in comparison to others cars in my same class.
The biggest difference was in rear spoilers.... they had Side spill plates
and I don't and some of them allowed air under the car... ( BIG DUST
TRAILS )
Some of the reasoning behind the way the rear deck lid is PURE luck and
some isn't.... Brad and I had to make some choices on how we did this....
I simply followed John Beckett's lead on the rear spoiler..... didn't
really pay it much mind at the time..... but I think John had it right.
John didn't have rear spill plates....
I am of the opinion that air is disturbed well above the spoiler surface at
least to a height equal to the height of the side spill plate. To prove my
thought I reviewed the tape at length looking solely at this issue and over
and over again those dust trails seem to be as high as the spill plate....
now since I can't see between the plates to see what is happening on the
width portion of the spoiler I can't tell you what is happening in that
region.... but it could be that the air flow is MUCH smoother and not an
issue..... and only that air in the region of the side plate is
disturbed.....
Sure wish we had an automotive aerodynamist on the list.... it would sure
be interesting to see how much of what we are saying is true or a myth....
K
----------
> From: Clay, Dale <Dale.Clay@mdhelicopters.com>
> To: 'ardunbill@webtv.net'; land-speed@autox.team.net
> Subject: RE: Aero Effects
> Date: Monday, July 30, 2001 12:48 PM
>
> Hi Bill,
>
> The shape of an aero object depends a lot on its use. While a teardrop
> shape does have a very low drag, when measured by itself, remember a
> bellytank car is running very close to the ground ("ground plane").
That,
> plus the wheels interfere with the air flowing around much of that body.
> Having said that when you hang that tank under a wing, the wing would act
as
> a ground plane as well, so ... My question about bellytanks involves
their
> angle of incidence. It would seem to be pretty sensitive to the angle of
> the tank relative to the ground as far as stability goes.
>
> The rear of the vehicle is VERY important. Air can only stay attached
> (laminar)at rearward taper of about 7 degrees before it becomes
turbulent.
> One other thing to consider in the rear is a rounded shape there can be
very
> unstable. This is because the point at which the smooth flow separates
from
> the surface is not consistent and can move the center of pressure around
on
> the body (think of a knuckle ball).
>
> I think it was Howard that mentioned the roostertail. This can be the
poor
> man's wind tunnel. The smaller that dust trail the better your aero
package
> is.
>
> Dale C.
>
>
> Subject: Aero Effects
>
>
> Hi Folks, the discussion about aero leads me to wonder if the classic
> lakester with a body made from an aircraft drop tank isn't the best. I
> assume many dollars were spent by the plane makers to find shapes that
> are aerodynamically neutral, no lift forces in any direction, and
> minimum drag.
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