Return-Path: <13brv3@bellsouth.net> Received: from imf23aec.mail.bellsouth.net ([205.152.59.71] verified) by logan.com (CommuniGate Pro SMTP 4.2.3) with ESMTP id 432201 for flyrotary@lancaironline.net; Sat, 25 Sep 2004 13:27:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.71; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf23aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20040925172704.XPTI1787.imf23aec.mail.bellsouth.net@rd> for ; Sat, 25 Sep 2004 13:27:04 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: oil filter, pressure test, ewp Date: Sat, 25 Sep 2004 12:27:20 -0500 Message-ID: <018301c4a324$e99edff0$04000100@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0184_01C4A2FB.00C8D7F0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 In-Reply-To: Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_0184_01C4A2FB.00C8D7F0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Interesting Rusty. My take on the oil pressure is that the restriction = of the oil cooler (evap core) is not a big factor. Who cares whether the pressure is dropped by the cooler or the oil pressure regulator? (until = it drops it below regulator spec of course) =20 =20 Agreed. I was just getting paranoid about having another failure of the = oil cooler, and felt compelled to actually prove what the pressure was. I = feel better now. =20 =20 Aren't these types of oil pumps considered positive displacement pumps? = In other words, they displace a certain volume with every turn. If that's = the case, it would seem that a higher volume pump would be a good thing for cooling. The extra volume would get bypassed at the regulator, and = would get sucked right back out of the pan and sent back to the oil cooler. = Just seems like this would be a way to get more cooling out of a given cooler size. It might not quite work that way in reality, but I'm just trying = to think of anything that could help oil temps. Not likely I'll be = changing oil pumps. =20 =20 What really concerns me is the poor oil cooling you are getting. I plan = to use an evap core for the 20B and on my mental scratch pad, it should be better than the Mazda oil cooler in aircraft applications. Wish I knew what the air pressure in front & back of your cooler is. Pressure = recovery is real important with evap cores.=20 =20 Don't get too concerned yet. It was working great before I started = making "C" power, despite the fact that the installation is far from ideal. = The oil cooler scoop looks nice, but doesn't have the best pressure recovery shape to it. The air has to turn about 60 degrees to get into the core, then about 80 degrees to exit the cowl. The rear face of the core is = also within 3-4 inches of the oil pan, so the exit area is restricted. In = other words, I don't think the core itself is to blame. Unfortunately, = without expanding the cowl in the downward direction, I can't see a way to = improve the geometry. Fortunately, that is a fairly reasonable solution, and = would offer some other benefits, such as increasing the cowl exit area, and = being able to fair in the muffler to some extent. =20 =20 My actual plan is to (eventually) use your ASI trick on both rads, and = the oil cooler. I assume the water cores are getting a much better pressure recovery than the oil core is. If that proves to be the case, and = since I still have some excess water cooling, I could swap the roles of the = right cheek core and the chin scoop core. That would make the left cheek and = chin cores water, and the right cheek core oil. This option isn't without = it's own problems when it comes to running hoses. =20 =20 With any luck, I'll have my repairs complete by the end of next weekend = (Oct 3rd), and will get back in the air. I've blown off all the other = fly-ins with Shady Bend being my only goal. It's going to be close, but I still might make it. =20 =20 Cheers, Rusty (surrendered Slingshot data plate, and airworthiness cert- just = parts pending rebuild and recertification now) =20 =20 ------=_NextPart_000_0184_01C4A2FB.00C8D7F0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
Interesting=20 Rusty.  My take on the oil pressure is that the restriction of the = oil=20 cooler (evap core) is not a big factor.  Who cares whether the = pressure is=20 dropped by the cooler or the oil pressure regulator? (until it drops it = below=20 regulator spec of course)  
 
Agreed.  I=20 was just getting paranoid about having another failure=20 of the oil cooler, and felt compelled to actually = prove what the=20 pressure was.  I feel better = now.  
 
Aren't these=20 types of oil pumps considered positive displacement pumps?  In = other words,=20 they displace a certain volume with every turn.  If that's the = case, it=20 would seem that a higher volume pump would be a good thing for = cooling. =20 The extra volume would get bypassed at the regulator, = and would get=20 sucked right back out of the pan and sent back to the oil cooler.  = Just=20 seems like this would be a way to get more cooling out of a given cooler = size.   It might not quite work that way in reality, but I'm = just=20 trying to think of anything that could help oil temps.  Not = likely=20 I'll be changing oil pumps. 
 
What really=20 concerns me is the poor oil cooling you are getting.  I plan to use = an evap=20 core for the 20B and on my mental scratch pad, it should be better than = the=20 Mazda oil cooler in aircraft applications.   Wish I knew what = the air=20 pressure in front & back of your cooler is.  Pressure = recovery is=20 real important with evap cores. 
 
Don't get too=20 concerned yet.  It was working great before I started making = "C"=20 power, despite the fact that the installation is far from = ideal.  The=20 oil cooler scoop looks nice, but doesn't have the best pressure recovery = shape=20 to it.  The air has to turn about 60 degrees to get into=20 the core, then about 80 degrees to exit the cowl.   The = rear face=20 of the core is also within 3-4 inches of the oil pan, so the exit = area is=20 restricted.  In other words, I don't think the = core itself is to=20 blame.   Unfortunately, without expanding the cowl in the = downward=20 direction, I can't see a way to improve the geometry.  = Fortunately,=20 that is a fairly reasonable solution, and would offer some other = benefits, such=20 as increasing the cowl exit area, and being able to fair in the muffler = to some=20 extent.  
 
My actual plan is=20 to (eventually) use your ASI trick on both rads, and the oil = cooler.  I=20 assume the water cores are getting a much better pressure recovery than = the oil=20 core is.   If that proves to be the case,  and since I = still have=20 some excess water cooling, I could swap the roles of the right cheek = core and=20 the chin scoop core.  That would make the left cheek and chin cores = water,=20 and the right cheek core oil.   This option isn't without it's = own=20 problems when it comes to running hoses. 
 
With any luck,=20 I'll have my repairs complete by the end of next weekend (Oct 3rd), and = will get=20 back in the air.  I've blown off all the other fly-ins = with Shady=20 Bend being my only goal.  It's going to be close, but I still = might=20 make it.  
 
Cheers,
Rusty=20 (surrendered Slingshot data plate, and airworthiness cert- just=20 parts pending rebuild and recertification=20 now)   
 
------=_NextPart_000_0184_01C4A2FB.00C8D7F0--