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From: Jeff Whaley <jwhaley@datacast.com>
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Engine cooling
Thread-Topic: [FlyRotary] Engine cooling
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Date: Fri, 9 Mar 2012 14:20:19 +0000
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I think the approach makes sense for the worse-case hot weather environment=
 but from a northern perspective you have to do something when it gets cold=
. If you design a system to cool at 100F OAT, your engine it is going to be=
 too cold at 0F OAT; in fact it will be exactly 100F less, typically 80F.
Right now I'm using grills that block off approximately 50% of inlet air fl=
ow; at 0F I add tape to reduce to 25% air flow.  This is of course only gro=
und adjustable but adequate for typical winter flying.  Running synthetic o=
il a bit too cool is less significant than running the glycol too cool.  My=
 long-term approach will be to install an in-flight adjustable flap to rest=
rict the outlet air of my radiator, which does not provide airflow over the=
 engine, only my oil coolers do that.
Jeff

-----Original Message-----
From: Ernest Christley [mailto:echristley@att.net]
Sent: Thursday, March 08, 2012 3:38 PM
Subject: Re: [FlyRotary] Engine cooling

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=B0F at cruise,
> and near 200=B0F 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 souther=
n 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.  Th=
e prescription given is to force the water to stay in the engine longer.  T=
his 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 s=
tops 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 radiato=
r.  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 therm=
ostats.  The panel would require minimal support, as it could simply lay fl=
at against the radiator face.

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