Did you happen to notice how I qualified the tape? it's a Maybe and Claims
have been made..... But like you and I talked about... it's a Maybe.... it
was sure worth sharing and discussing the theory.... The Whole deal may or
not have merit but the discussion on boundry layers is worth the effort in
it's own right....
I think I need to clear something up.... so no one misunderstands me.... I
have a degree in Aeronautic's from Embry Riddle Aeronautical University...
What that means Is I am a Professional Pilot...( which I was before I got
the degree) but I have a fascination with Aerodynamics and there effects on
an automobile.... I am NOT an aerodynamisist.... Just a guy who took a
strong interest in the theory of Flight...and how airflow applies to a
car....... Like the rest of you most of my study is Pure OD guess work....
oh and I look at what others have done before me....
Keith
----- Original Message -----
From: "DrMayf" <drmayf@teknett.com>
To: "Dick J" <lsr_man@yahoo.com>; "Keith Turk" <kturk@ala.net>; "Dan Warner"
<dwarner@electrorent.com>; <land-speed@autox.team.net>
Sent: Thursday, February 22, 2001 11:30 AM
Subject: Re: Aeronautical question for Keith, MAYF and other engineers ??
> I had promised myself that I woullld not intercede on the dimple tape.
But,
> I see now that I must. If you reread the original thread on the tape you
> will find that the author had some trouble proving the fact that dimple
tape
> works. I found that amusing because...least drag is found using laminar
> boundary layers. Ie smooth air flow from front to back. There was also
some
> chat about tripping the boundary layer. Here is the real deal...tape added
> to the smooth air flow fouls up the boundary layer. So you think, maybe if
> the boundary layer is off the car, it will go faster? Nope. Here is what
my
> aero experience and texts say...." Because of the oscillation of the fluid
> particles in the turbulent boundary layer, an interchange of momentum and
> energy is possible among the individual layers comprising the the complete
> bounday layer. This permits a transfer of energy from the free stream
> through the outer portion of the layer to the inner portion, with the
> result that the turbulent layer has a fuller velocity profile than a
liminar
> layer and a steeper gradient at the surface. The greater capicity of the
> turbulent boundary layer to remove energy from the fre stream as compared
to
> the laminar layer not only results in a higher energy level throughout the
> turbulent layer, but also increases skin-friction drag,owing to grater
> energy loss in the free stream."
>
> If this worked, every race car that is used to race for money would have
it
> everywhere. The cars themselves would be dimpled every where. As to
tripping
> the boundary layer, the edge of the tape does that, let alone the
"dimples".
> The best drag reducing is to have a seamless car, painted with a really
good
> paint and waxed to death. Smooooothhhhhhhh....
>
> so in my estimation, putting dimples on the bottom of the pan would in
fact
> slow the air causing a high pressure build up under the car and, well you
> get the idea...
>
> Oh, now you want to talk about golf balls...ok, dimples are added to golf
> balls for stability. Sorta like the rifling on a gun barrel. Remember a
golf
> ball can spin up to 10,000 rpm off a high number club and 2500 to 2800 off
a
> driver. The spinning with the dimples tries to keep the ball flight as
> stable as possible. Does not reduce drag to my knowledge, but might
because
> of the spherical surface...
>
> mayf
>
>
> > Keith,
> > After all our jawing and joking about dimple tape
> > last week, your belly pan question got me
> > thinking=(DANGER! Danger, Will Robinson!) Do I
> > have this backwards or is this a valid theory?
> > If the entire belly pan was dimpled, and the top
> > of the car was smooth, there would be less drag
> > on the belly pan than on the top of the car,
> > mimicking the same effect as more air flow under
> > the car, resulting in an effect like an upside
> > down wing - which would add downforce as speed
> > increased. Or did I get that backwards, and the
> > car would take off like a frizzbie?
> >
> > =====
> > Dick J
> > In East Texas
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