X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 25 Sep 2011 23:37:08 -0400 Message-ID: X-Original-Return-Path: Received: from nskntmtas04p.mx.bigpond.com ([61.9.168.146] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTP id 5135609 for lml@lancaironline.net; Sun, 25 Sep 2011 06:14:36 -0400 Received-SPF: pass receiver=logan.com; client-ip=61.9.168.146; envelope-from=frederickmoreno@bigpond.com Received: from nskntotgx03p.mx.bigpond.com ([124.180.125.148]) by nskntmtas04p.mx.bigpond.com with ESMTP id <20110925101359.TWGU1385.nskntmtas04p.mx.bigpond.com@nskntotgx03p.mx.bigpond.com> for ; Sun, 25 Sep 2011 10:13:59 +0000 Received: from Razzle ([124.180.125.148]) by nskntotgx03p.mx.bigpond.com with ESMTP id <20110925101358.PGGG22866.nskntotgx03p.mx.bigpond.com@Razzle> for ; Sun, 25 Sep 2011 10:13:58 +0000 MIME-Version: 1.0 X-Original-Message-Id: <4E7EFEDB.0000A6.01908@RAZZLE> X-Original-Date: Sun, 25 Sep 2011 18:13:47 +0800 Content-Type: Multipart/Alternative; charset="iso-8859-1"; boundary="------------Boundary-00=_ZQP2T71AMY5000000000" X-Mailer: IncrediMail (6244788) From: "Frederick Moreno" X-FID: FLAVOR00-NONE-0000-0000-000000000000 X-Priority: 3 X-Original-To: "Lancair Mail (lml@lancaironline.net)" Subject: Oil question for Walter A X-Authentication-Info: Submitted using SMTP AUTH LOGIN at nskntotgx03p.mx.bigpond.com from [124.180.125.148] using ID frederickmoreno@bigpond.com at Sun, 25 Sep 2011 10:13:58 +0000 X-SIH-MSG-ID: oh02GdL+TFa2kTAvmTy2alorgFm6/gF5uMhSBI0wt0lHEVbCu8XAQsKjbaJDxJDn0DZcVV/bLgJ1I7zmWJ/QstOxIrZUUqDb5/kNsw== --------------Boundary-00=_ZQP2T71AMY5000000000 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable "Everybody"knows that when you put "too much" oil in your aircraft engine (that is, fill it up to the top level), it will blow oil overboard. =0D =0D But I am mystified after seeing how our engines are constructed. =0D =0D On my Continental IO-550, the oil in the pan can not "see" the crankshaft spinning overhead because the crank is nearly entirely enclosed by the crankcase housing, with only narrow semicircular slits in the casting allowing oil to drain from around the crank and bearings down to the oil = pan So there is very little windage effect possible to disturb the surface = of the oil in the sump. =0D =0D There is a cracked Lycoming 0-360 crankcase in my hangar, and it has narr= ow slots oriented parallel to the crank centerline through which oil drains = to the crankcase so in this design the prospect of windage reaching the oil surface in the crankcase seems remote indeed. =0D =0D Yet, adding two quarts of oil which may raise the oil level half an inc= h on a big engine makes the difference between oil going overboard or not going overboard. =0D =0D Why? What seems obvious is now not so obvious when I think about it and=20 try to visualize what is going on inside. =0D =0D The only idea that came up in discussion is that there is a layer of oil foam on top of the oil in the sump, and it builds up deep enough to block the drain slots or allow oil foam to churn around the crankshaft. That seems like a stretch, except that a friend who used to work at Garrett to= ld me he saw a Garrett turbocharger on the test stand, and what came out the bottom of the turbo was not oil, but more like brown mayonnaise that was sucked up by the scavange pump and returned to the engine. But turbos wi= th bearings at slight negative pressure (and suckng air through seals) are n= ot crankshafts at positive pressure. =0D =0D Reading about oil foaming ascribes it to water in the oil, an abnormal condition. Engine oil have anti foaming agents. =0D =0D So to Walter or anyone: please explain how adding one to two quarts of oi= l causes oil to be blown out? =0D =0D Fred Moreno, mystified (as usual) --------------Boundary-00=_ZQP2T71AMY5000000000 Content-Type: Text/HTML; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
"Everybody"knows that when you put "too much" oil in your aircr= aft engine (that is, fill it up to the top level), it will blow oil overb= oard.
 
But I am mystified after seeing how our engines are constructed.&nbs= p;
 
On my Continental IO-550, the oil in the pan can not "see" the crank= shaft spinning overhead because the crank is nearly entirely enclosed by = the crankcase housing, with only narrow semicircular slits in the casting= allowing oil to drain from around the crank and bearings down to the oil= pan.  So there is very little windage effect possible to disturb th= e surface of the oil in the sump.
 
There is a cracked Lycoming 0-360 crankcase in my hangar, and it has= narrow slots oriented parallel to the crank centerline through which oil= drains to the crankcase so in this design the prospect of windage reachi= ng the oil surface in the crankcase seems remote indeed.
 
 Yet, adding two quarts of oil which may raise the oil lev= el  half an inch on a big engine makes the difference between oil go= ing overboard or not going overboard.
 
Why?  What seems obvious is now not so obvious when I think abo= ut it and  try to visualize what is going on inside.
 
The only idea that came up in discussion is that there is a layer of= oil foam on top of the oil in the sump, and it builds up deep enough to&= nbsp;block the drain slots or allow oil foam  to churn around the cr= ankshaft.  That seems like a stretch, except that a friend who = used to work at Garrett told me he saw a Garrett turbocharger o= n the test stand, and what came out the bottom of the turbo was not = oil, but more like brown mayonnaise that was sucked up by the scavan= ge pump and returned to the engine.  But turbos with bearings at sli= ght negative pressure (and suckng air through seals) are not crankshafts = at positive pressure.  
 
Reading about oil foaming ascribes it to water in the oil, an abnorm= al condition.  Engine oil have anti foaming agents. 
 
So to Walter or anyone: please explain how adding one to two quarts = of oil causes oil to be blown out? 
 
Fred Moreno, mystified (as usual)
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