Ed Huntress wrote:
"cavelamb himself" wrote in message
...
Ed Huntress wrote:

"Too_Many_Tools" wrote in message
...
On Mar 26, 11:41 pm, "Ed Huntress" wrote:

snip

This isn't very hard to do, once you get some practice. I taped yarn
tufts
all over my racing ITC Fiesta (yeah, I know -- it wasn't much) in the
mid-80s and videotaped it from another car driving on an Interstate. I
was
checking the effects of propping up the rear of the hood, which was legal
in
SCCA's ITC class.

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Ed Huntress- Hide quoted text -

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Excellent idea.

TMT

It is not original. g Several good books on building racecars describe
it, and that's where I learned it.

--
Ed Huntress

What was the idea?

Vent off the high pressure area in front of the windshield?


Richard
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Oh, jeez, maybe I misunderstood what TMT was commenting about. I thought he
meant that the yarn tufts are a good idea. They are, but they're also a very
old idea.

Regarding propping the hood, the idea is to let hot air out from under the
hood. I know, the bottom of the windshield often is a high pressure area,
but it's another old idea. An ITC Fiesta didn't generate enough extra heat
that you had to worry about the overheating issue.

The reason I was trying it was to see if I could delay separation for a
couple of inches down the hatchback window. I know, it was unlikely to do
anything at that remote distance, but I was curious.

FWIW, the sharp edges on the Fiesta started turbulence every which way, but
then it re-attached. Over the top, it re-attached about halfway along the
roof, and then it promptly got turbulent again, before you got to the rear
window.

I also put closed-tube manometers (made from aquarium hose) at different
points around the car and tried *that*. The car was an aerodynamic mess.

I recall when Fiestas first came out much was made of the grill slats,
supposedly designed so that as speed increased, air packed in front of
them so at higher speeds it was like a flat panel with just enough
airflow to keep the motor cool, the rest going around to aid aero.