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Chris Barber wrote:
Just some data points for discussion. PLEASE if you know some stuff that
is rotary specific, or just wrong, CHIME IN!!
Chris
Houston
Cooling Guidelines for V8 Engines in Aircraft
by Bud Warren and Phyllis Ridings
After much thought, Bud decided to install a thermostat in the LS1
engine of the Ravin 500 to do some test flying. During cold weather the
resulting engine temps have remained stable at 190°F at cruise, and
near 200°F during climb out; just about what we see during the warm
months of the year. This has corrected the check engine light coming on
due to the engine remaining in warm up mode.
This approach makes me nervous. It doesn't hit us much here in the southern US, but things get colder as we move north.
When it is freezing on the ground, it's very easy to get REALLY cold temps at altitude. If it is 0*F on the ground,
then the rule of thumb says that it will be -40* at altitude.
The problem described is that the engine isn't able to produce enough heat to warm the water with the amount of -40*F
air that is rushing through. The prescription given is to force the water to stay in the engine longer. This
necessarily means that the water will stay in the radiator longer. Now the thermostat opens even less, because what it
pulls from the radiator is ice water. At some point, the water gets really hard in the radiator and stops flowing
altogether. The there is no flow from the engine to melt it. The engine water keep recirculating and it eventually
overheats.
The Mack truck I bought in the late 80's had a shutter arrangement in front that would close when it got to cold and
block airflow through the radiator. I think a thin aluminum panel, possibly controlled by a push-pull cable from the
cockpit, that slid in to partially block the radiator would be a much safer solution. It would also alleviate the
concern over broken thermostats. The panel would require minimal support, as it could simply lay flat against the
radiator face.
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