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
Here is the square box Schertz beam. This opens up underneath the
flywheel
for more air to the rad.
Charlie lay out your side mounted rad. I think you will have trouble
ducting
enough air to it. the plumbing will be more complicated as well.
Paul Lamar
I don't think trying to fold sheet metal to form this S-beam will
lead to happiness. However, it might be possible to do something
rather neat with mild steel structural channel. There is one that is 3
inches deep with a 1.41 inch flange. It is .170 inches thick. It is
much stronger than the .063 hat section. There is no reason this
could not be lightened by milling to reduce the thickness or even
better by lightening holes which take out the weight but not the
strength. They can look cool, too., In the area where the 3.050
outside dim. is critical, one could either shim or build up the area
and then mill it back to a precise fit. Since it is hot rolled, each
beam's width would have to be checked. And since it is mild steel, a
little extra weight might be required but not much. Before lightening,
a 24 inch beam would weigh 8.2 lbs.--- Jerry
That is a bit heavy and crude. I still say the right shop can bend the 4130.
How is the availability of 4130 these days? I can get some and have it
bent up for you. Modest cost. I have a friend in the precision
sheet metal business that can handle this no problem.
Paul Lamar
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