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Neil says:
<current thinking of running a thermostat, yes , no or possibly
Safety decisions trump all others. I'd encourage using thermostat for the
first 30 flights. You should also make sure you measure BLOCK temperature, not
radiator or some other area. That way you will know if thermostat behaving
properly prior to takeoff (Block temp would be hotter than normal during taxi if
thermostat stuck closed. )
You don't want to increase workload during those first flights just for
purpose of improving efficiency. Playing with a stupid coolant flap during
initial flights not recommended. Likewise, normally coolant temp causes big
mixture changes. Why screw with it? Let engine run at normal operating temp for
less risk of mixture issues (more stable).
After 30 flights, then it's reasonable to consider flying without
thermostat if you desire reduced drag by choking off rad air flow. There might
be a small risk reduction by removing thermostat, although it would fail any
test for significance.
-al wick
----- Original Message -----
Sent: Sunday, October 13, 2013 1:23
PM
Subject: [FlyRotary] Re: waterless
coolant?
Regarding coolants of both types, what is the current thinking of running
a thermostat, yes , no or possibly? Neil.
Sent: Sunday, October 13, 2013 11:08 PM
Subject: [FlyRotary] Re: waterless coolant?
Good discussion on that link Michael. Although I noticed one of the
posters referred to 30% glycol mix as 70%. Making it quite confusing.
Over the years, I've encountered pilots who've done good job of measuring
Evans vs. glycol temperatures. We would expect them to have 20% higher temps,
but usually find 15% or so. I'm always intrigued when the occasional person
describes that Evans reduced their temp. It defies physics. But when you think
about it, it's possible that person started out with trapped air in system.
When converting to Evans, he may have eliminated that trapped air. Thus sees
much improved cooling. That's my best guess. That and pareidolia.
-al wick
----- Original Message -----
Sent: Friday, October 11, 2013 4:16
PM
Subject: [FlyRotary] Re: waterless
coolant?
Al:
I did a bit more digging on
the stuff and came up with this which makes the same point.
Michael Silvius
Scarborough,
Maine
----- Original Message -----
Sent: Friday, October 11, 2013 10:33
AM
Subject: [FlyRotary] Re: waterless
coolant?
I've researched this product thoroughly and used to do fluid heat
transfer experiments in my occupation. If you drained all the fluid in
your radiator, replaced it with 100% antifreeze (normal ethylene glycol)
you'd have identical boiling point and heat transfer characteristics to
Evans product. So you could operate zero pressure, as it wouldn't boil
over until it reached 392F.
Unfortunately both Evans and 100% glycol have very low heat transfer
coefficient (.66). They are both insulators, so all things being equal,
you have to increase your radiator area by 30% to achieve the same engine
operating temperature. Compared to running with 30% glycol mix, that's
quite a penalty.
Ethylene glycol is substantially superior to Evans, as you can tune
it's efficiency by adding water. For example, it you decide to operate
with more efficient 50/50 mix, the heat transfer coefficient jumps from
.66 to .86. You get to reduce your radiator size a lot, yet still have
230F boiling point.
Evans has a great propaganda web site, a lot of people get sucked in.
It's one of those rare products that has zero redeeming value. Far
inferior to glycol. Yet I bet it will continue to sell for decades.
-al wick
----- Original Message -----
Sent: Thursday, October 10, 2013
11:15 AM
Subject: [FlyRotary] Re: waterless
coolant?
You might want to check what happens to the viscosity of this fluid
at lower temperatures. Its been a while, but as I recall this
fluid turns into heavy syrup at lower temps. You can
visualize your water pump churning (cavitating) in a void of this
fluid at low temperatures while not moving any through your cooling
system.
The fluid next to the rotors would undoubtedly get hot -while
that in the radiator and water pump may act as a (Temporary) plug to
coolant flow – until the heated fluid explosively forces the
issue.
I tried finding the viscosity charts they used to have on the site,
but could not find it.
My impression when I looked into this fluid back a few years ago,
was that this heavy viscosity at low temps was probably not much of a
draw back compared to the benefits in a racing motor – heated
garage, summer temps, etc. But, might be a different story for
aircraft application.
Ed
Edward L.
Anderson
Anderson Electronic Enterprises LLC
305 Reefton
Road
Weddington, NC
28104
http://www.andersonee.com
http://www.eicommander.com
Sent: Thursday, October 10, 2013 1:05 PM
Subject: [FlyRotary] Re: waterless
coolant?
This
appears interesting. I looked at the website and was unable to
find the heat capacity of the fluid. The higher boiling temp may
not be helpful if the heat capacity is such that you need a large delta
T to transfer the same amount of heat as a water-based
system.
One
must also consider the effect of the higher operating temperature on
engine oils. At some temperature, oil loses its lubrication
ability. I don’t know what that temp is but assume it is different
for different oils. Just because the coolant allows higher
operating temperatures, doesn’t mean one should do
that.
Gordon
C. Alling, Jr., PE
President
acumen
Engineering/Analysis,
Inc.
540-786-2200
www.acumen-ea.com
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of
Michael Silvius
Sent: Thursday, October 10, 2013 1:19
PM
To: Rotary motors in aircraft
Subject:
[FlyRotary] waterless coolant?
While on the subject
of cooling, I am curious if anyone has tried the waterless coolant?
Seems to offer some advantages, namely higher boiling boint and low
pressure, is there any reason it should not be used in our
aplication?
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