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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: Sat, 10 Mar 2012 01:29:39 +0000
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From: Charlie England <ceengland@bellsouth.net>
Subject: Re: [FlyRotary] Re: Engine cooling
Date: Fri, 09 Mar 2012 16:45:55 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

I detect a pun Charlie ... yes I only have one bottom too ... butt only one=
 radiator, so one bottom is enough.
Jeff

Butt I've only got one bottom. Are you different?
:-)
_______________________________________
From: Jeff Whaley
Sent: March 9, 2012 12:59 PM
To: 'Rotary motors in aircraft'
Subject: RE: [FlyRotary] Engine cooling

Ooops, I mis-quoted him; he says 1.5 sq in per cu in of engine ... however,=
 we aren't cooling cu in of engine we're cooling HP.
So, to me the math I presented before and below makes more sense ... 1.5 sq=
 in per HP.
Jeff

-----Original Message-----
From: Jeff Whaley
Sent: Friday, March 09, 2012 12:54 PM
To: 'Rotary motors in aircraft'
Subject: RE: [FlyRotary] Engine cooling

Yes, he has the math correct; however, I agree with Ernest about the applic=
ation of stating one thing and doing another.
300 Hp x 1.5 sq in =3D 450 sq in  ...  when in fact he uses 540 sq in. or a=
n additional 20%.
300 Hp x 3.0 cu in =3D 900 cu in  ...  when in fact he uses 1215 cu in. or =
an additional 35%.
So what is the true minimum requirement?
Also, if side air scopes are great due to their alignment with outer prop t=
ips, then bottom cowl air scoops should work as well.

Jeff

From: Ernest Christley <echristley@att.net>
Subject: Re: [FlyRotary] Re: Engine cooling
Date: Fri, 09 Mar 2012 11:10:50 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>


Tracy wrote:
> Sanity check:
>
> 1) Requirement: Radiator surface required is 1.5 sq in of surface area
> per cubic inch of the engine. For example: LS1 V8 Chevrolet =3D 350 cu
> in x 1.5 =3D 525 sq in of radiator surface area required. For this
> purpose, this applies only to the surface area of the radiator that
> the air flow first makes contact with.
>
>
> 2) Requirement: Minimum of 3.0 cu in of cooling volume per HP produced.
> For example: We only utilize up to 300 HP of an LS1 for aircraft use.
> Using a dual radiator configuration with two radiators measuring 15=94 x
> 18=94 x 2.25=94 thick =3D the total cooling volume is 1215 cu in.
> Therefore, our cooling volume to HP ratio: 1215 cu in cooling volume =F7
> 300 HP =3D 4.05 cu in per HP. With this formula, we have been able to
> maintain climb out temperatures of around 200=B0F and 190=B0F at cruise o=
n
> a 100=B0F day. With a cooling system like this, we could taxi from
> Houston to Dallas with no overheating problems.
>
> Is it just me or is the math here bogus?
>

He's got dual radiators that add up to 540in^2 of surface and 1215in^3 of v=
olume.  The math is right.
What doesn't add up to me, is that he says you can get by with 3in^3/hp, bu=
t then demonstrates that 4in^3/hp is just adequate on a reasonably hot day.=
  I would not take issue with the math, just his definition of what constit=
utes "minimum".


-----Original Message-----
From: Jeff Whaley
Sent: Friday, March 09, 2012 9:21 AM
To: 'Rotary motors in aircraft'
Subject: RE: [FlyRotary] Engine cooling

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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