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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-853926@logan.com>
Subject: Re: [FlyRotary] Re: Cooling -Learned a lot
Date: Mon, 4 Apr 2005 08:36:40 -0400
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I have only read this one book (actually chapter 12)  on liquid aircraft
cooling, its seems to be the ONE.  It is not light reading, but   chapter 12
presents the liquid cooling challenge for aircraft in what appears to me to
be a fairly complete manner. You do have to did into it a bit.  No, the book
has been out of print for decades.  I finally got a bound Xerox copy from a
foreign source with good legibility but that was about the best I could say.
Pages were out of order, upside down, etc. but like I said the information
was legible.

The book is "Aerodynamics of Propulsion" by Kuchemann and Weber better know
as "K&W"
published by McGraw-Hill in 1953.  I searched long and hard for a copy and I
found none in the typical out of print book sellers.

There is one other book  Hoerner Fluid Dynamics that is reported to be a
good one as well, but I have not acquired that one as yet.


I'll have to see if I can find my source for K&W,  it was back a few years
ago and I have had a couple of harddisk crashes since then.

Ed
----- Original Message -----
From: "Michael Burke" <mburke@southernphone.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, April 04, 2005 2:47 AM
Subject: [FlyRotary] Re: Cooling -Learned a lot


> Ed is this book the"Holy Grail" on liquid cooled aircraft engines. Is it
> still available from book stores, if not where can it be purchased.
> Many Thanks,
> Rotary Newbie,
> Michael.
>
> ----- Original Message -----
> From: "Ed Anderson" <eanderson@carolina.rr.com>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Monday, April 04, 2005 12:14 AM
> Subject: [FlyRotary] Cooling -Learned a lot
>
>
> > Too right, Jerry
> >
> > My  first 40 hours or so were in the marginal cooling zone. {:>).  As
> other
> > things in this hobby, there are so many variables that interact, that
what
> > may appear simply at first, is almost always a bit more complex.  I
> > say(Cooling Axiom 1) if you have enough cooling surface area and air
mass
> > flow then it WILL cool.    However, you may incur a high penalty in
> cooling
> > drag - which may not be as important for draggy airframes (such as
> biplanes)
> > as it is to sleeker airframes.   Also a system that adequately cools an
> > engine producing  150 HP may not cool an engine producing 180 HP.
Picking
> > your cooling design point is important.  Optimizing for cruise and your
> will
> > be less than optimum for take and climb.  Optimize for climb and you
will
> > probably have more cooling drag than required at cruise.  Compromise,
> > compromise - cowl flaps are sometimes used to try to have the best of
both
> > worlds.
> >
> > Some folks advocate a thinner, larger surface area core -which is great
> for
> > slow moving automobiles stuck in traffic with low dynamic pressure
> > potential, but I think is not the optimum for most aircraft.  Once you
> trip
> > the airflow and turn it turbulent you have incurred most of the drag
> > penalty.  Larger surface area cores disrupt a larger airstream and incur
> > more drag.  Yes, thicker cores produce a bit more drag than the SAME
> frontal
> > area thinner cores.  But, with a thicker core you can use a core with
> > smaller frontal area.
> >
> >   The NASCAR radiator's average 3" thick and on the long tracks where
> speeds
> > are higher some even go up to 7" thick.  My contention is their
operating
> > environment is more akin to ours than regular automobiles moving at
slower
> > speeds.  You know that the NASCAR folks will spend $$ for just a tiny
> > advantage - so clearly they don't use thick cores because it is a
> > disadvantage. But, some folks will continue to point to the large thin
> > radiators designed for environments with much lower dynamic pressure as
> > being the way to go.  Will it cool? sure it will (Cooling axiom 1
above).
> > Is it the lowest drag option for an aircraft of the RV/TailWind type, I
am
> > convinced it is not.
> >
> > The diffuser makes a considerable amount of difference and can made the
> > difference between a system that cools adequately and one which does
not.
> > The biggest culprit that lessens cooling effectiveness is turbulent
eddies
> > that form inside the duct due to flow detachment from the walls.  These
> > eddies in effect act to block effective airflow through part of the
core.
> > So keeping the airflow attached to the sides of the diffusers is crucial
> for
> > good cooling from two standpoints. A good diffuser will reduce airflow
> > velocity through the core which will reduces cooling drag.  Pressure
> across
> > the core is increased which further enhances cooling.
> >
> > I have gone from a total of 48 sq inches opening (total) for my two GM
> cores
> > and that provided marginal cooling - down to 28 sq inches (total) with
> > adequate cooling with an engine now producing more HP.  Experimenting
with
> > the diffuser shape made the difference.
> >
> > The K&W book (Chapter 12) really provided the insight to how and which
> > diffuser shapes provided the better dynamic recovery.  The Streamline
duct
> > was shown to be able to provide up to 82% recovery of the dynamic
> pressure.
> > Some folks reading the chapter misinterpreted the chart to show only 42%
> > recovery where there chart was actually only showing the pressure
recovery
> > contribution due to the duct walls and did not include the contribution
> due
> > to the core.  On the same chart, an equation (which apparently gets
> ignored)
> > clearly shows that the TOTAL  pressure recovery is 82%.
> >
> > I have taken the Streamline duct as a starting point, but since I do not
> > have the space to provide the 12-14" for a proper Streamline duct, I did
> > some "creative" things to try to insure that there was no separation
even
> > though my walls diverge more rapidly than the Streamline duct.  Won't
> claim
> > mine are as good as a Streamline, but they clearly are much better than
> the
> > previous design which basically just captured the air and forced it
> through
> > the cores.
> >
> > FWIW
> >
> > Ed Anderson
> > RV-6A N494BW 275 Rotary Hours (Plugs Up)
> > Matthews, NC
> > eanderson@carolina.rr.com
> >
> >
> > ----- Original Message -----
> > From: "Jerry Hey" <jerryhey@earthlink.net>
> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > Sent: Sunday, April 03, 2005 9:27 AM
> > Subject: [FlyRotary] Re: phase I flight restrictions was:N19VX flys
> >
> >
> > > It was not long ago that "cooling" was the major issue.  Now it seems
> > > that we have learned enough to make several different configurations
> > > work.   I can't lay my finger on what it is we have learned but my
> > > recommendation is to use smaller radiators and EWPs.   Jerry
> > >
> > >
> > >
> >
> >
> >
> >
> > >>  Homepage:  http://www.flyrotary.com/
> > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >
>
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html