REFLECTOR: Re: radiator size

["Wayne Owens" <wamowens@bellsouth.net>]

----- Original Message -----
From: <RGVelocity@aol.com>
To: <wamowens@bellsouth.net>
Sent: Friday, June 04, 1999 7:24 AM
Subject: radiator size


> Wayne,
>
> Glad you're back! Thanks for the reply. I suppose my real question at this
> point is what was the minimum size radiator that was adequate on the test
> stand, and from your initial estimates, were you able to get away with a
> smaller one than you thought due to the augmentation. I figure once in the
> air, cooling should be no problem, therefore I was shooting for the
smallest
> possible to do the job on the ground, what do you think? Thanks.
>
> Mark
Charley Airesman sure thinks augmentors  helped him get by with less.
My initial radiator on the ground wouldnt cool the plane and after several
antics and  schemes to use prop suction to get air through the radiator  I
finally tried the augmentors. That got the manometer readings up to 5,4
inches ( approx  90 kts) and found the engine was still heading toward
overheat.  The next radiator even with only a 50 kt wind cooled the plane.
Mick Myal cautioned me "dont assume it will cool better in the air"  the
loads are much higher during climb and lots more heat is generated. Mick
was relating observations about a fellow who had overheat related forced
landings.
Cubic inches of radiator  seem more important than square area assuming
a3.75 inch thick core. With our air velocitys the consenssus seems to be
thick rads are better.
My first rad  fin area was 22 x 5 x  3.75. Ron Davis said it was enough but
I couldnt make it work.  My current radiator  fin area is 23.5 x 3.75 x
7.25.  On the test stand with a 50 kt prop blast I could just stabilize
temperature at cruise on a 90 + degree day. The engine is a 3.3 litre (201
c.i.) 230 Hp  engine.  The ratios roughly concur with those suggested in
CONTACT Magazine
Rather  than building a too small system and having to do it over think
about having plenty and a cowl flap to reduce drag during cruise. With your
HP prop efficiency or something else is likely to limit your top speed
anyway.
Wayne