X-Mozilla-Keys:                                                                                 
Al Gietzen wrote:

Paul;

We are delighted for you that you found your basic folded radiator concept
in the book :-).  So you probably noticed that it shows the outlet smaller
than the inlet; which may mean the fluid passing through is being cooled
instead of heated; but, whatever.

What troubles me is is 'How much does the air need to be slowed
(pressure recovered) to behave nicely and make those turns through the
radiator?' The amount of air flow is determined by the amount of heat
rejected and the delta T of the air going through.  This air flow then
determines the size of inlet scoop area needed.  Then in order to get the
air to flow through with minimal pressure drop, it has to be slowed down by,
say about a factor of four or five (i.e.; the diffuser area at the radiator
is now four-five times the inlet area) and whala! (english version); we no
longer have any use for a compact heat exchanger.

For a climbout power of, say 160hp, a 13B will need about 60 sq. in. of
intake area at 100 kts. The diffuser cross-sectional area then becomes
250-300 sq. in.; plenty big enough for the radiator face area needed (and
maybe too big to manage inside the cowling).

Am I missing something here?

Al Gietzen

No Al all that sounds about right. It was intended to replace 
one of those thick rads in a P51 type scoop. Since I drew that
I have decided the cool tip whenever possible is do something 
inside the the cowl. The external plumbing is daunting and why
add a bunch of frontal area. Let's take advantage of the tiny
size of the rotary. The side exhaust is the key. That usually
gives plenty of room under the engine for an adequate
sized radiator. The plumbing is then as simple as possible.

BTW I am not so enamoured of the book Compact Heat Exchangers.
I could find no reference to anti-freeze and one row 
radiators which are now the industry standard for cars.
All experimental work included in the book was completed by 1984.
The lack of properties on anti-freeze is inexplicable.
Perhaps the work, being sponsored by the Navy, is the answer.
The Navy never ever believed in liquid cooled air craft 
engines :-)

The one SAE paper on rads given me by Juergen Bax at Wankel
is more relevant to our needs. I am off to the tech
library tomorrow to see if I can find more late SAE papers
on rads.

Paul Lamar
 
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