From: David Lednicer <dave@amiwest.com>
Newsgroups: rec.aviation.homebuilt
Subject: Re: COOLING DRAG
Date: Tue, 13 Oct 1998 09:22:16 +0100

> Aerodynamics hasn't changed a great deal since then either.  We have
> learned some more about it, but it is still the same as it has always
> been.  Of course, we can always ignore that an apply the 1917
> aerodynamics because it sounds right to us.

	Nonsense - aerodynamics has progressed significantly since 1917!  Our
knowledge of how to cool engines has progressed significantly too.
Personally, I think a major landmark was in the late 1970s/early 1980s
when Stan Miley did his pioneering work on cooling drag.  However, in my
experience, those designing cooling systems don't do their homework and
keep repeating the mistakes of the past.  Miley lays out the information
needed to properly design a low drag cooling system for an air cooled
engine.  Similary, Kuchemann has laid out much of what one needs to know
to design a low drag cooling system for a liquid cooled engine.

-------------------------------------------------------------------
David Lednicer             | "Applied Computational Fluid Dynamics"
Analytical Methods, Inc.   |   email:   dave@amiwest.com
2133 152nd Ave NE          |   tel:     (206) 643-9090
Redmond, WA  98052  USA    |   fax:     (206) 746-1299

From: David Lednicer <dave@amiwest.com>
Newsgroups: rec.aviation.homebuilt
Subject: Re: Speaking of airfoils
Date: Wed, 08 Dec 1999 09:14:11 +0000

Mike Sieweke wrote:
>
> Larry -xlax- Lovisone <netters2@ns.net> wrote:
>
> > Big deal... So how does the P-51 66-416 wing

Ahhemm....  The P-51A, B, C, D and K do not have the NACA 66-416.  They
use a one-of-a-kind airfoil designed by NACA working in conjunction with
NAA.  It has been labeled the 45-100.  You can find coordinates of it on
the UIUC airfoil web site.  The P-51H and J have a NACA 66-(1.8)15.5 at
the root and a NACA 66-(1.8)12 at the tip.  For more info, see the
Incomplete Guide to Airfoil Usage at:
http://amber.aae.uiuc.edu/~m-selig/ads/aircraft.html

> The 66 series airfoils are designed for 60% laminar flow, but the
> thickest point is at 45% of the chord.

No, max t/c is at 60% on this series.

> > Where did the P51's speed come from???
> > Not the radiator... hot or cold... it's pure drag...

Try again - if you compress air, add heat and then reexpand it, you get
thrust.  This is how a jet engine or a ramjet works.  A properly
designed cooling system works the same way.  The trouble is, a radiator
doesn't add much heat compared to a combustor.  Hence, the thrust is
low, but it can balance out cooling system drag, which I believe it does
on the P-51.

-------------------------------------------------------------------
David Lednicer             | "Applied Computational Fluid Dynamics"
Analytical Methods, Inc.   |   email:   dave@amiwest.com
2133 152nd Ave NE          |   tel:     (206) 643-9090
Redmond, WA  98052  USA    |   fax:     (206) 746-1299

From: David Lednicer <dave@amiwest.com>
Subject: Re: Speaking of airfoils
Newsgroups: rec.aviation.homebuilt
Date: Thu, 09 Dec 1999 09:37:31 -0800

  The "Ahem" was because YOU didn't check facts - you had the wrong
airfoil identified for the P-51.  On the other hand, I am just as
guilty, as you are right about the 66-series.  I usually figure max t/c
is at the max run length for favorable pressure.  However, as you have
pointed out, this is not true for the 66-series.

                         -David Lednicer
                          using Remarq because my mail service sucks

From: David Lednicer <dave@amiwest.com>
Subject: Re: Speaking of airfoils
Newsgroups: rec.aviation.homebuilt
Date: Fri, 10 Dec 1999 08:52:16 -0800

  My apologies - I had to dig quite a ways back in the threads to see
that it was Larry, not you.  Your reaction to my "Ahem" fooled me.  You
also taught me something about the NACA 66-series.  However, I still
stand by my statements on Riblett.

                           -David Lednicer