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Re: Tear drop (fwd)

To: "answer landracing" <land-speed@autox.team.net>
Subject: Re: Tear drop (fwd)
From: pork.pie@t-online.de (Pork Pie)
Date: 04 Jan 2003 20:06 GMT
Okay, this question is very serious, so I sit down and give some more 
information.

The last week, someone wrote that a square got a Cd from 1,0. If he meant a 
flate plate standing in the air than is this figure wrong. by a very low speed 
it's 1,0 - by high speed and using the Reynolds number the Cd of a flate, 
square plate is 1,28.

The teardrop - 3.5 times length to the total width is the minimum base for good 
effective tear drop - this will bring you a result which is 1/32 of a flate 
plate Cd.

If you go to a 6 to one, the aerodymic will be much more effective.
But carefully. This kind of teardrop is everywhere round - it means - on the 
front you start with a radius and from there on - when you go sideways, you 
increase the radius size, bigger and bigger, so that at last this radius left 
and right joint to the rear end.
The radius increase follows a mathematical 6 degrees curve after the biggest 
cross sestion of the teardrop.
A teardrop with a radius in front and than a straight line to the rear end 
needs the 6 degrees rule.
Confussed enough? If you need more information, I can make a sketch to explain 
this.
So let me know if there is not everything clear.

See ya

Pork Pie



<wmtsmith@landracing.com> schrieb:
> Jon, I read that a teardrop needs a 4 times length to width to be 
>effective--I am trying to use a 6 to one. 
> 
>  Now the question I don't know--do you figure 1/2 the width and that is the 
>relationship for just that side or do you have to use total width? wmts
> > 
> > From: "Jonathan Amo" <webmaster@landracing.com>
> > Date: 2003/01/03 Fri PM 09:47:52 EST
> > To: "LSR List" <land-speed@autox.team.net>
> > Subject: wisdom or not wisdom
> > 
> > List,
> > 
> > Im out here, just reading and accepting and analyzing what I read as in does
> > it make sense and can I contribute or take the information and put it to 
>use.
> > 
> > I do have a question as to streamlining.
> > 
> > Jack C I really want you to pop in about this subject.
> > 
> > We all have heard that a teardrop shape is "sapposed" to be the most
> > areodynamic shape. Even thinking about one of those rainbow trout. No Keith
> > not those brown trout you probably fish for. At what point does this shape 
>not
> > be benefit. What length in otherwords would this shape be or not be
> > beneficial? 5ft? 10ft? 25ft?
> > I have heard that the air coming around the subject if to short will 
>"collide"
> > at the rear of the subject, if it does not have time to smooth out. So how
> > long does it need to smooth out?
> > 
> > Anybody have any beneficial info on the subject.
> > 
> > Jonathan
> 
> 
> 
> 

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