X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 13 Mar 2009 06:07:46 -0400 Message-ID: X-Original-Return-Path: Received: from QMTA07.westchester.pa.mail.comcast.net ([76.96.62.64] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3545894 for lml@lancaironline.net; Thu, 12 Mar 2009 23:21:41 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.62.64; envelope-from=nrgarvin@comcast.net Received: from OMTA13.westchester.pa.mail.comcast.net ([76.96.62.52]) by QMTA07.westchester.pa.mail.comcast.net with comcast id SR1B1b00p17dt5G57TM6UD; Fri, 13 Mar 2009 03:21:06 +0000 Received: from nrggateway508 ([71.234.116.252]) by OMTA13.westchester.pa.mail.comcast.net with comcast id STM51b00H5SotVj3ZTM6ho; Fri, 13 Mar 2009 03:21:06 +0000 From: "neal garvin" X-Original-To: "'Lancair Mailing List'" References: Subject: RE: [LML] Re: oil cooling/Vernatherm X-Original-Date: Thu, 12 Mar 2009 23:21:08 -0400 X-Original-Message-ID: <42BDC58C422C4F13B8D0FB2767B2074C@nrggateway508> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0124_01C9A369.39A02560" X-Mailer: Microsoft Office Outlook 11 In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Thread-Index: Acmjan5xjkBEQdl8TIOmp5SkeKTXiwAHlrrQ This is a multi-part message in MIME format. ------=_NextPart_000_0124_01C9A369.39A02560 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit The vernatherm works the opposite as you might think. When it is cold, it opens the shortcut passage inside the vernatherm that causes the oil to bypass the cooler and go back to the engine. The passage to the cooler is still open but the oil takes the path of least resistance and flows into the engine. When the oil is hot, this shortcut passage is blocked off forcing the oil to go to the cooler. Most high oil temp problems are caused by insufficient airflow through the cooler. This is due to insufficient pressure differential across the cooler. You can have plenty of blast air hitting the face of an oil cooler but if the hot, expanded exit air can't depart the other side free of any obstructions or slightly increased lower cowl pressure then the cooler won't function well. If you have an air duct & hose on the back side of the cooler it needs to be 3x the diameter of the feed hose to accommodate the 3x volume of hot expanded air. A balloon makes a good illustration, especially in winter. Blow one up then put it outside and watch it shrink. The best mounting for an oil cooler is such that the exit air dumps directly overboard to a low pressure area. The P51 Mustang is a good example. The Glasair III mounted to the side of the lower cowl has proven to work well also. _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Sky2high@aol.com Sent: Thursday, March 12, 2009 7:30 PM To: lml@lancaironline.net Subject: [LML] Re: oil cooling/Vernatherm Randy, Oh, I forgot. I also replaced the Vernatherm, but I don't remember technical details of the testing (a long story involving a flash fire - best told in a bar). I believe the chamber that the Vernatherm operates in is such that, when cold, allows oil to bypass being sent to the cooler. When hot, the extension of the device shuts the bypass opening. Thus, if the Vernatherm does not fully extend when hot, the bypass is not sealed and uncooled oil would be returned to the system. Here is one example of test results: http://www.vansairforce.com/community/showthread.php?t=32763 Here is some interesting info, click on tech data: http://www.rostravernatherm.com/oil-valves.htm Here is a more interesting read: http://www.sacskyranch.com/eng18.htm Scott. In a message dated 3/12/2009 9:35:08 A.M. Central Daylight Time, randylsnarr@yahoo.com writes: Scott, I was thinking the same thing and am making plans to "redo" my oil cooler to cowl connection and make it nice and smooth. That will happen after I verify the vernatherm is doing what is supposed to... I pulled out the vernatherm the other day and put it in boiling water to see what it would do. I admit I really do not understand how it works but the spring loaded end got about 1/8" longer when going from room temp to 212 F. Does that mean it is working? If anyone knows if this is good or bad, please pipe in... Thanks for the feedback! Randy Snarr --- On Tue, 3/10/09, Sky2high@aol.com wrote: From: Sky2high@aol.com Subject: [LML] Re: oil cooling To: lml@lancaironline.net Date: Tuesday, March 10, 2009, 8:36 PM Randy, My large sharp edged NACA duct is poorly placed on the left rearward side of cowling. It enters a short flexible 3" smooth rubber sleeve (plumber's sleeve) and then to a plenum above the small SW oil cooler mounted to the fire wall. The bottom is open to the lower cowl. I climb at about 135 KIAS and see cylinders occasional reach 400 degrees on a hot day while the oil stays at 180. In cruise in 30-40F temps, I must at least partially close the door between the NACA and the cooler. Recently, in 10C temps, I had to completely close the door to keep the oil temps about 180. In the pattern at 100 KIAS I will see the oil go 190F or even 200F on hot days because of lack of air thru the cooler. It wasn't always that way. When I had high oil temps, I tried a special cooler air exit to assist, no help.. Another was to try exiting thru shark gills on the side of the cowl, no help. I temporarily attached a scoop to force more air in the duct, no help. I finally discovered that the air was backed up in the NACA duct plenum (or chamber), thus cutting off air flow. I used Micro to smoothly shape the chamber, thus directing the air into its 3" outlet (no more dead corners) with the results detailed above. Good Luck, Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) In a message dated 3/9/2009 12:41:32 P.M. Central Daylight Time, marv@lancair.net writes: Posted for randy snarr : All, Thanks for the good suggestions on the oil cooler. I flew again today and my oil temps are at 208 F flying in 35 f air. They will be 215 or 220 this summer. I will try a few solutions that do not need to cut the cowl. I will most likely make a duct to carry the exhaust air from the oil cooler down to the lower aft part of the cowl. I have also heard that the aft vertical edge of the naca opening should be shaped like an air foil. Mine is flat and fairly sharp. The easiest way to test will to be construct a piece to give it a little airfoil made from balsa or foam taped in place and flight tested. If that does not work, I will make a duct from the cooler to the low pressure area on the bottom of the cowl and lastly would be a small lip on the bottom of the cowl aft. every producton airplane I have seen with an opening on the bottom of the cowl has 45 deg lip to create a low pressure area. I should have done that before I painted.... I will post my findings when I get them. Randy Snarr N694RS -- SFor archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html _____ A Good Credit Score is 700 or Above. See yours in just 2 easy steps! _____ A Good Credit Score is 700 or Above. See yours in just 2 easy steps! ------=_NextPart_000_0124_01C9A369.39A02560 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

The vernatherm works the opposite = as you might think. When it is cold, it opens the shortcut passage inside the vernatherm that causes the oil to bypass the cooler and go back to the = engine. The passage to the cooler is still open but the oil takes the path of = least resistance and flows into the engine. When the oil is hot, this shortcut passage is blocked off forcing the oil to go to the = cooler.

 

Most high oil temp problems are = caused by insufficient airflow through the cooler. This is due to = insufficient pressure differential across the cooler. You can have plenty of blast air = hitting the face of an oil cooler but if the hot, expanded exit air can’t = depart the other side free of any obstructions or slightly increased lower cowl pressure then the cooler won’t function well. If you have an air = duct & hose on the back side of the cooler it needs to be 3x the diameter = of the feed hose to accommodate the 3x volume of hot expanded air. =

 

A balloon makes a good = illustration, especially in winter. Blow one up then put it outside and watch it shrink. The best mounting for an oil cooler is such that the exit air dumps directly = overboard to a low pressure area. The P51 Mustang is a good example. The Glasair = III mounted to the side of the lower cowl has proven to work well = also.

 

 

 

 

From: = Lancair Mailing List = [mailto:lml@lancaironline.net] On Behalf Of Sky2high@aol.com
Sent: Thursday, March 12, = 2009 7:30 PM
To: = lml@lancaironline.net
Subject: [LML] Re: oil cooling/Vernatherm

 

Randy,

=

 

=

Oh, I forgot.  I also = replaced the Vernatherm, but I don't remember technical details of the testing (a = long story involving a flash fire - best told in a bar).  I believe the = chamber that the Vernatherm operates in is such that, when cold, allows oil = to bypass being sent to the cooler.  When hot, the extension of the = device shuts the bypass opening.  Thus, if the Vernatherm does not fully = extend when hot, the bypass is not sealed and uncooled oil would be returned to = the system.

 

=

 

=

Here is some interesting info, = click on tech data: http://www.rostra= vernatherm.com/oil-valves.htm

 

=

Here is a more interesting read: = http://www.sacskyranch.com/= eng18.htm

 

=

Scott.

=

 

=

In a message dated 3/12/2009 = 9:35:08 A.M. Central Daylight Time, randylsnarr@yahoo.com = writes:


Scott,

I was thinking the same thing and am making plans to "redo" = my oil cooler to cowl connection and make it nice and smooth. That will = happen after I verify the vernatherm is doing what is supposed to...
I pulled out the vernatherm the other day and put it in boiling water = to see what it would do.
I admit I really do not understand how it works but the spring loaded = end got about 1/8" longer when going from room temp to 212 F.
Does that mean it is working?
If anyone knows if this is good or bad, please pipe in...

Thanks for the feedback!
Randy Snarr
--- On Tue, 3/10/09, = Sky2high@aol.com <Sky2high@aol.com> wrote:


From: Sky2high@aol.com <Sky2high@aol.com>
Subject: [LML] Re: oil cooling
To: lml@lancaironline.net
Date: Tuesday, March 10, 2009, 8:36 PM

Randy,

 

My large = sharp edged NACA duct is poorly placed on the left rearward side = of cowling.  It enters a short flexible 3" smooth rubber sleeve (plumber's sleeve) and then to a plenum above the small SW oil cooler = mounted to the fire wall.  The bottom is open to the lower cowl.  I = climb at about 135 KIAS and see cylinders occasional reach 400 degrees on a = hot day while the oil stays at 180.  In cruise in 30-40F temps, I must at = least partially close the door between the NACA and the cooler.  = Recently, in 10C temps, I had to completely close the door to keep the oil temps = about 180. In the pattern at 100 KIAS I will see the oil go 190F or even = 200F on hot days because of lack of air thru the = cooler. 

 

It wasn't = always that way.

 

When I had = high oil temps, I tried a special cooler air exit to assist, no = help..

Another was = to try exiting thru shark gills on the side of the cowl, no = help.

I temporarily = attached a scoop to force more air in the duct, no = help.

 

I finally = discovered that the air was backed up in the NACA duct plenum (or chamber), thus = cutting off air flow.  I used Micro to smoothly shape the chamber, thus directing the air into its 3" outlet (no more dead corners) with = the results detailed above.

 

Good = Luck,

 

Scott Krueger AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, = IL (KARR)

In a message = dated 3/9/2009 12:41:32 P.M. Central Daylight Time, marv@lancair.net = writes:

Posted for randy snarr <randylsnarr@yahoo.com>:

 All,
 Thanks for the good suggestions on the oil cooler.
 I flew again today and my oil temps are at 208 F flying in 35 f = air.
 They will be 215 or 220 this summer.
 I will try a few solutions that do not need to cut the cowl. I = will most
likely make a duct to carry the exhaust air from the oil cooler down = to the
lower aft part of the cowl. I have also heard that the aft vertical = edge of
the naca opening should be shaped like an air foil. Mine is flat and = fairly
sharp. The easiest way to test will to be construct a piece to give it = a
little airfoil made from balsa or foam taped in place and flight = tested. If
that does not work, I will make a duct from the cooler to the low = pressure
area on the bottom of the cowl and lastly would be a small lip on the = bottom
of the cowl aft.
 every producton airplane I have seen with an opening on the = bottom of the
cowl has 45 deg lip to create a low pressure area. I should have done = that
before I painted....
 
 
 I will post my findings when I get them.
 
 Randy Snarr
 N694RS
 

--

  

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http://mail.lancaironline.net:81/lists/lml/List.html
 



A Good Credit Score is 700 or Above. See yours in just 2 easy steps!

 

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