X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qmta12.westchester.pa.mail.comcast.net ([76.96.59.227] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTP id 5435763 for flyrotary@lancaironline.net; Fri, 09 Mar 2012 19:36:57 -0500 Received-SPF: none receiver=logan.com; client-ip=76.96.59.227; envelope-from=gordon@acumen-ea.com Received: from omta19.westchester.pa.mail.comcast.net ([76.96.62.98]) by qmta12.westchester.pa.mail.comcast.net with comcast id jaGh1i00227AodY5CccR4T; Sat, 10 Mar 2012 00:36:25 +0000 Received: from GordonHPelite ([76.27.173.182]) by omta19.westchester.pa.mail.comcast.net with comcast id jccQ1i0163wUsn83fccQm3; Sat, 10 Mar 2012 00:36:24 +0000 From: "Gordon Alling" To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Re: Engine cooling Date: Fri, 9 Mar 2012 19:36:19 -0500 Message-ID: <004a01ccfe55$cfd52770$6f7f7650$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_004B_01CCFE2B.E6FF1F70" X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: Acz+T+VQ+0sY1CSvQWmFjiAmdeBa4AABLDTA Content-Language: en-us This is a multi-part message in MIME format. ------=_NextPart_000_004B_01CCFE2B.E6FF1F70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable These are clearly empirical relationships based on some unspecified = number of data points. They include implicit assumptions about the heat = exchanger configuration (frontal area to volume ratio). Thus, the validity for = other HX configs is undetermined. That said, these guidelines provide a reasonable starting point if one is not going to do a full-fledged HX analysis. I always say that all the analysis in the world only tells me where to start testing. I appreciate the input and will consider these parameters in selecting my cooling system comnponents. =20 Gordon C. Alling, Jr., PE President acumen Engineering/Analysis, Inc. =20 540-786-2200 www.acumen-ea.com =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Tracy Sent: Friday, March 09, 2012 10:31 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Engine cooling =20 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.=20 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.=20 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 on a = 100=B0F day. With a cooling system like this, we could taxi from Houston to Dallas = with no overheating problems.=20 Is it just me or is the math here bogus?=20 Tracy On Fri, Mar 9, 2012 at 9:20 AM, Jeff Whaley = wrote: 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 flow; at 0F I add tape to reduce to 25% air flow. This is of course = only ground adjustable but adequate for typical winter flying. Running = synthetic oil 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 restrict 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 = southern 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. = The prescription given is to force the water to stay in the engine longer. = This 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 = stops 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 = radiator. 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 thermostats. The panel would require minimal support, as it could = simply lay flat against the radiator face. This message, and the documents attached hereto, is intended only for = the addressee and may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received = this message in error, please notify us immediately so that we may correct = our internal records. Please then delete the original message. Thank you. -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html =20 ------=_NextPart_000_004B_01CCFE2B.E6FF1F70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

These are clearly empirical = relationships based on some unspecified number of data points.=A0 They include implicit assumptions = about the heat exchanger configuration (frontal area to volume = ratio).=A0 Thus, the validity = for other HX configs is undetermined.=A0 That said, these guidelines = provide a reasonable starting point if one is not going to do a = full-fledged HX analysis.=A0 I = always say that all the analysis in the world only tells me where to = start testing.=A0 =A0I appreciate the input and will = consider these parameters in selecting my cooling system = comnponents.

 

Gordon C. Alling, Jr., = PE

President=

acumen Engineering/Analy= sis, Inc.

 

540-786-2200

www.acumen-ea.com

 

From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Tracy
Sent: Friday, March 09, 2012 10:31 = AM
To: Rotary motors = in aircraft
Subject: = [FlyRotary] Re: Engine cooling

 

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” x 18” x 2.25” 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 on 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?

Tracy

On Fri, Mar 9, 2012 at 9:20 AM, = Jeff Whaley <jwhaley@datacast.com> = wrote:

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 flow; at 0F I add tape to reduce to 25% air flow.  This = is of course only ground adjustable but adequate for typical winter = flying.  Running synthetic oil 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 restrict 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 southern 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.  The prescription given is to force = the water to stay in the engine longer.  This 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 = stops 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 radiator.  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 thermostats.  The = panel would require minimal support, as it could simply lay flat against = the radiator face.

This message, and the documents attached = hereto, is intended only for the addressee and may contain privileged or = confidential information. Any unauthorized disclosure is strictly = prohibited. If you have received this message in error, please notify us = immediately so that we may correct our internal records. Please then = delete the original message. Thank you.

--
Homepage:  http://www.flyrotary.com/
Archive and UnSub: =   http://mail.lancaironline.net:81/lists/flyrotary/List.h= tml

 

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