Mailing List flyrotary@lancaironline.net Message #624
From: Tom Kendall <Tom.Kendall@att.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: [FlyRotary] Re: Coolant loss : More cooling system test stuff.
Date: Sun, 01 Dec 2002 15:53:56 -0500
To: <flyrotary>
Well, not quite.  Visualizing thermal expansion is something that gives everybody headaches.  Simply put: on the inside everything gets farther apart just like on the outside.  So the volume of the cavity for the coolant actually gets larger.
 
Think of it this way:  you are sitting on the edge of a hole drilled in a plate.  As the plate heats up, the metal starts expanding away from you in all directions.  The far side of the hole expands away from you too.
 
But the thermal expansion coefficient for liquids is inevitably much greater than for metals.  So much so, that any change in the volume of the tank (or engine cavity) is trivial in comparison.  The liquid expansion dominates.
 
Tom Kendall
----- Original Message -----
From: Al Gietzen
Sent: Sunday, December 01, 2002 1:04 AM
Subject: [FlyRotary] Re: Coolant loss : More cooling system test stuff.

Another factor that affects the coolant volume is the expansion of the metal in the engine.  The coolant is essentially contained in an annular region around the rotors.  The inside of that annulus gets pretty hot.  Could be that the coolant capacity in the engine is decreased. 
 
I have no idea how big a factor this is, but it seems that that overall coolant "expansion" is more in a rotary.  I'd estimate that the amount of coolant that gets pushed into the catch bottle on the V-8 in my van is a pint or less.
 
Al

.Tracy and others, what is the theory behind so much liquid in the external
expansion tank? Thermal expansion of the initial coolant volume doesn't
account for such a large overflow. So is vapor building up inside? If it is
there is no longer a liquid filled system. I don't get it.
Peter


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