Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Mon, 24 Mar 2003 01:10:09 -0500
Message-ID: <redirect-2084479@logan.com>
Reply-To: "Tracy Crook" <lors01@msn.com>
From: "Tracy Crook" <lors01@msn.com>
References: <list-2083788@logan.com>
Subject: Re: [FlyRotary] Re: Thick or Thin? The debate continues
Organization: Real World Solutions Inc.
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Tracy wrote:
 D@*x!, lost another 2 hour message to the blue screen of death.

David Leonard wrote:

> More air CAN cause less drag if it is going slower. Again the argument
> lies in the fact that drag is a function of velocity CUBED (not squared
> as I previously stated - I think maybe laminar flow is velocity squared)
> but mass of air to only the first power.  A quick search found this
> classic discussion of parasitic vs. induced drag which illustrates the
> velocity cubed point:
> http://www.paraborne.com/how_airplanes_fly_3.html
>
> Drop the velocity of the air, the drag drops by a 3-fold factor.
> Increase the mass, and drag only increases by a one-fold factor.
> More air has the added benefit of not requiring each packet to gain as
> much heat, allowing an overall higher temperature gradient.

Tracy replies:

 OK here is the guts of what I blathered on for two hours about:

You are correct about the importance of the velocity of air in the drag
equation.  But the air velocity through the rad is of no (or very minor)
importance.

The velocity that matters is the velocity of the air at it's *source*.
That, of course, is the speed of the air rushing past the airplane that we
snagged to run through our cooling system.  Since this speed is the same
regardless of what radiator is sitting inside the cowl, the *only* factor
that makes any difference is how much of that air we used.  More air = more
energy = more drag.

Tracy