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What a thorough analysis Ed. I really enjoyed reading it. I always consider
the next step is to do some simple tests that prove these conclusions. Only
because too much reliance on theory often leads to lost perspective. Well,
that's been my experience anyway.
In spite of Dave's experience, I really find that higher boiling point real
attractive. I try to encourage guys flying unknown cooling systems to take
advantage of the safety margin you get from boiling point. Even though I
don't use Evans myself. I consider boil over the number one coolant
risk item.
Do you guys have anyone flying with evans?
Thanks for sharing your analysis. -al wick Artificial
intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+
hours on engine/airframe from Portland, Oregon Prop construct, Subaru
install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html
Things have been a little dull on the list, since Dave
reported on his "adventure".
Also, I recently received a phone call from a
rotary enthusiast (not on the list) about the use of Evans NPG (Propylene
Glycol) in rotary engines. I did a bit of research and my conclusion was
the rotary engine was not well suited to benefit from the properties of
NPG in its stock coolant system configuration.
That the use of 100% glycol would require
increased coolant flow rates by 10-15% and more coolant pump power would
be required (hard to quantify this one but it appears in the range of 15-25%
more). Also the hazard of fire due to a leak on hot exhaust would be
increased (this would apply to a 100% mixture of either Ethylene or Propylene
glycol). There are benefits to using NPG, however, in my opinion the
effort needed to change the rotary cooling configuration to safely
use it makes the cost effectiveness of the conversion
questionable.
The apparent success of Evans NPG in reciprocating
engines is not in conflict with my assessment about its suitability for the
rotary engine.
Attached is some supporting (I believe) facts to support
this opinion (and that is all it is).
Ed
-al wick
Artificial intelligence in
cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on
engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk
assessment, Glass panel design
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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