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Thats it exactly Earnest. Nail on the head. The theoretical advantage of the thin over the thick only exists with optimum ducting. In reality, a thick radiator with good ducting is going to be better than a thin radiator with sub optimal ducting - and both are much better than a system that does not fit at all.
BTW, you're not going to get me to underestimate of the difficulty of making it all happen :-)
--
David Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net
On Nov 13, 2007 9:19 AM, Ernest Christley < echristley@nc.rr.com> wrote:
David Leonard wrote:
> Why is it going slower? BECAUSE YOU HAVE DESIGNED YOUR THIN RADIATOR SYSTEM
> DUCTS SUCH THAT AN EQUAL AMOUNT OF AIR PASSES THROUGH AN EQUAL VOLUME OF
> RADIATOR AS WOULD OCCUR ON A THICK RADIATOR SYSTEM. (This is the big if...
> system design... but bear with me). ie, equal amount of air, equal volume
> of radiator - in the thin radiator system the air will be flowing more
> slowly.
>
I agree with your concept, Dave, but I think you underestimate the
difficulty of fitting a large faced radiator into the physical
constraints of the area available in a small airplane. I worked on
trying to use a large, 1" thick radiator for a while, and this was in a
delta planform. I had comparitively HUGE amounts of volume to work
with. I eventually gave up, as there was just no reasonable way to get
a duct built around it that would slow the air down. As you increase
the face area, you increase the size of the duct necessary to expand the
air without separation. The best radiator and duct ever created will be
useless if we have to leave it on the ground because it doesn't fit in
the airplane.
I think the flow chart for sizing a radiator for our needs should follow
something like this:
1) Mark out a space for the largest volume that you can fit a radiator
and its associated ducting into. Insure that routing for the hoses will
be convenient, and the ducting can be made something resembling efficient.
2) Visit one of the websites like frigidair.com and find a radiator that
meets the dimensional specs you came up with. Or contact Jerry and have
him make you one of that size.
3) If the core volume is less than 700 cubic inches, add another.
4) Go fly. If it is to cool (<160F), choke off the inlet a little. If
it is to hot (>200F), fiddle with the ducting.
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