|
I was wondering more about the temperature of the plastic shroud
itself.
Being very close and directly above the cylinder heads I assume
it would
get very soft during a hot soak. True? Should it be made
from aluminum?
I'm less worried about wires and such as wire insulation is
silicone and
should take it. I'm not sure the mags would get any hotter
inside the
plenum than behind the engine, but that is pure speculation as I
have no
data. Also, is there any reason to join the two sides of the
plenum? Why
not build two small plenums, one on each side? Also,
one of the links from
a previous post described a "RTV BID." Did they
really mean impregnating
cloth with RTV? I assume that would make a
flexible structure? I was
puzzled.
Gary Casey
My LNC2 has a plenum chamber and many of you have seen it at the Lancair
Redmond Fly-In on Labor Day weekend. The plane was completed in
1999.
The plenum top is constructed of 4 bid E-glass with two, 1/8 "
thick glassed-over foam stiffeners on the underside. It also has removable
glass ramps from the bottom of the cowl inlets (bottom half of the cowl) that
fit in slots and pockets (for flex) all made of the same fiberglass
material. The ramps actually touch the cooling fins on the front
cylinders.
I have had no problems with fiberglass deformation with the plenum top or
the ramps related to high heat. The airbrushed picture on the plenum top
also has shown no indications of heat stress over time.
I have seen aluminum plenums, but fiberglass would be much easier to deal
with the curves and compound angles under the cowl.
I thought about two separate plenums in the beginning. And I already
had my cowls built. It would have been more work, and after 10 years of
building, I was ready to get the plane finished.
Gary Edwards
LNC2
N21SN
|