On Wed, 1 Sep 2004 15:52:22 -0500, "Russell Kent"
wrote:

The radiator wants an unobstructed path for the air leaving. Facing the
firewall is non-optimal. Adding an exhaust pipe makes it worse. Also, be
certain the exhaust pipe cannot radiate heat into the radiator.

Poor description of the location on my part, my apologies. The
radiator will be set in a cut out at the bottom of the firewall. This
is a Christavia, which is a big airplane. The firewall extends down
below the fuselage tubing so that there is a section underneath the
fuselage tubing that is unused space. I have cut out a section of the
firewall where the radiator's duct will pass through and still have
the firewall protecting the foot well. The area that forms the exit
duct will be made from the same firewall material so that the
firewall, in effect, continues as the exit duct.

The exhaust system by the time it reaches this duct, consists of two S
shaped 2 inch tubes. They sweep in from the side and then turn and
face the rear about a foot behind the radiator. They terminate about
6 to 8 inches from the end of the radiator exit duct. This gives the
exhaust outflow a chance to accelerate the air behind the radiator.

This is nothing new. Exhaust augmentation has worked on a number of
military airplanes and continues to work on civilian airplanes. It's
just more complicated to arrange than simply sticking the exhaust pipe
out the cowling.

Corky Scott