OK thanks Charlie.
The lower cowl is still a couple of inches too deep in this 3D. Looks
like
a water rad under the engine is not practical with the Schertz beam
so
you will have to
use evap cores like Tracy and Bill Schertz used. There is room of
course for the
oil cooler and people seem to have more trouble with that than water
cooling.

Why cannot a 22/24 inch wide radiator be fitted,  lying flat under
the
engine.  The Intake plenum above it has only to clear the 1.5 inch
beam.  The beam may facilitate hanging the rad as it provides
something to attach to.  I'm going to install  a piece of  hat
section
 across the back of the engine so I can hang the other end of the rad
as well.    The Tailwind firewall is only 25 inches from top to
bottom
and I have mocked up the rad/plenum installation before.  It seemed
to
be doable.       Jerry

Once I corrected the lower cowl dimensions a good size rad and stock
RX7 oil
cooler does fit side by side. The only problem is that 1-1/2 inch high
Schertz beam gets in the way of the air coming in over the top of the
rad.
20 inches wide by 1-1/2 inches high is a considerably area. 30 square
inches to be exact. This is about 30% of the area required to get air
into the
rad and oil cooler. That space under the flywheel is critical real
estate.

Fortunately I have a solution. Yet another Schertz beam configuration.
This one does double duty as a motor/PSRU plate spacer. It utilizes
the two large
lower ten mm bolts that are used to hold the motor/PSRU plate to the
end housing.
No clips are needed and no pan bolts are used. It is tricky to make
however and it can only be this size and no larger. Still made out of
4130 .065 sheet steel. The flywheel just fits in the slot on top of
the beam.

Paul Lamar

Taking the path of least resistance,  I think we should follow Bill's
example and mount the oil cooler under the beam.  It is a natural
location.  Nothing wrong with cheek rads, either.  They are proven.   I
forget how long the stock cooler is but it would be a good idea to make
the Barry centers far enough apart  that  it could be hung between
them.   Oil cooler mounting brackets can be part of the package.  Jerry

The problem with cheek rads is the need to open up the intake to obscene 
proportions :) This cause more drag than necessary.

More complicated  plumbing. So far we have lost the vast majority 
of rotary powered airplanes to plumbing failure.

There is just not enough room in there to get a proper diffuser. They are too 
thick so it takes a lot of air speed (dynamic pressure = V^2) to get the air 
to flow through them. 

They work sort of but you must compromise your climb. In Florida
it is less of a problem because once you reach 500 feet you rarely
need to climb higher. 

I don't like them. I think we need to move beyond evap cores.

Paul Lamar
 
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