I have been working on and off (mostly off) on an exhaust augmentation
system
for my EA81 powered monowheel. The idea is to use the waste heat of the
exhaust to do the cooling for you instead of using high drag ram pressure
thru the
rad. The Reno racers do this and claim it adds up to 20 mph while improving
cooling. Inlet duct areas can be dropped to almost nothing as the augmenter
creates a huge suction effect to suck cooling air thru the rad from behind.
Racers who have used this arrangement report up to 4 inches of suction. A
standard flow thru ram type duct arrangement typically only gives an inch of
pressure difference even if done well. Theoretically, one could reduce the
rad
size dramatically as a result, saving more weight and drag (maybe by half or
more).
The engine exhaust pipe will enter the duct at the big bulge and terminate
about
6 inches inside the duct. This then creates a high speed jet of exhaust
that mixes
with the back side radiator air and the mixing creates an enormous suction
on
the back side of the rad. It all fits very snug and the long oval shaped
tube tucks
in right beside the monowheel. It looks heavy but the kevlar tube is only a
pound
and the fiberglass duct is only a pound, replacing the rear duct I already
use.
I have one radical idea that I will try and that is to not use a front
difffuser duct
at all, and just let the radiator suck air from the inside of the cowling.
Hopefully,
that would be near zero cooling drag.
Ground cooling is claimed to be excellent as well, as cooling is entirely
determined
by engine rpm, not airspeed. One should be able to run WOT on the ground as
long as desired without overheating as suction is doing all the work, not
ram
pressure. Also, reports are that the long mixing tube only gets warm to the
touch.
The system should be peaches on a 912/914 powered unit as well although
you
would need a 4 into 1 type exhaust.
Glenn
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