My coupe has the two landing lights mounted to the nosebowl ring.  The
lights
look through openings in the nosebowl but are not attached to it.   The
opening is sealed poorly with a metal band which approximates the shape of
the cowl but does a poor job of sealing the opening.  That means that any
air
which leaks alongside of the light is that much less air available to cool
the engine.  The last few years I have worked out a system of sealing the
opening with foam rubber strips  but I am still not particularly happy
with
it.

For the benefit of those who are new to coupes and aircraft in general,
cooling an airplane works like this.  The J-3 Cub was cooled by simply
hanging the cylinders out in the breeze.  That works at low power but has
its
limitations.  The radial engine exists in an attempt to give each cylinder
a
clean look at the airflow. Fred Weik is responsible for putting the ring
cowling on radial engines which improved cooling while reducing drag.

At the other end of the cooling picture are aircraft like the Mooney where
a
box is built over the top of the engine which forces all of the cooling
air
to flow through the cooling fins to get from the top of the engine to the
lower engine compartment,  The standard for tightness is that a total of
extra openings equal to more than a quarter is too much and needs to be
addressed with  silicone and baffle material.  Leaks on this system can
have
a large effect on the cooling of the engine.

The Ercoupe lies between these two designs.  The airbox exists and works
but
it is nowhere near as tight as on modern designs.  Nevertheless it is
important that no extra air is introduced into the lower engine
compartment
and that is my problem with the design.  I seem to have removed one
cylinder
at each annual over the ten years that I have had the plane.  The left
front
cylinder is a Millennium with 50 hours and its' exhaust valve is leaking
so
it has to come off for repair when the weather warms up a bit.  This will
be
the second time that a cylinder in that position has to come off for a
leaking exhaust valve.

Considering the difficulties I have had sealing the cooling air and
problems
with cylinders, the leading edge of the wing looks good to me.  A 100 watt
bulb attached to the nosebowl could be a nice installation but
manufacturing
the required covers and parts would not be a small project.  I believe
that
my installation was done by Metcoair in the late 60s but I have not looked
up
the paperwork in a long time.

Bob Condon

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