Ed Anderson wrote:

Hi Paul,

    You asked about the new inlet duct modification.

....................

 I first filled the duct with the liquid expanding foam, then shaped

and

added some lightweight filler to smooth the surface. I used the

paper

templates (Mvc33)to try to stay as close to the spreadsheet curves

as I

could.

Ed

In any event I think you are better off with a cowl flap as closing

the

cowl flap will build back pressure in the duct and cause external

diffusion

thereby automatically streamlining the inlet externally.
...............................
On the other hand the Kays & London simple wedge shaped diffuser

requires

no more length than the rad lying on its side. I now think this
is the best approach as it uses a minimum of under cowl volume or

space.

Paul Lamar

Ed,
I am very interested in how your tests go with the revised ducts, since

you

had pretty good cooling with the original ducts.

Bill Schertz

Hi Bill

Yes, current ducts are working just fine in the cooling department.
However, I felt that the duct shape was probably causing "eddies" around the
inside of the opening and disrupting some air flow/cooling.  Plus the
current openings are 24 square Inches for each radiator.  I thought that if
the smoother transistion from duct to radiator improved the air flow into
the duct then perhaps I could reducing the opening.  However, Paul, may be
correct  about my old duct cooling better as I reduced the opening from 25
in^2 to approx 10in^2 on the new duct. Perhaps a bit overly zealous {:>).

If the new duct does cool as well as the old duct, then I believe I will
have reduced some of the cooling drag, if not, then I rip out the foam and
go back to the old duct.  Hope to make first flight tomorrow and will let
everyone know of the results.

Ed Anderson

 
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