Return-Path: Received: from [216.52.245.18] (HELO ispwestemail2.mdeinc.com) by logan.com (CommuniGate Pro SMTP 4.2.3) with ESMTP id 434664 for flyrotary@lancaironline.net; Mon, 27 Sep 2004 19:00:57 -0400 Received-SPF: none receiver=logan.com; client-ip=216.52.245.18; envelope-from=wschertz@ispwest.com Received: from 7n7z201 (unverified [67.136.146.16]) by ispwestemail2.mdeinc.com (Vircom SMTPRS 3.2.315.0) with SMTP id for ; Mon, 27 Sep 2004 16:00:22 -0700 Message-ID: <001201c4a4e5$c3abf8b0$10928843@7n7z201> From: "William" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Oil viscosity Date: Mon, 27 Sep 2004 18:00:15 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01C4A4BB.D7A79420" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 This is a multi-part message in MIME format. ------=_NextPart_000_000F_01C4A4BB.D7A79420 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageI realize flow and pressure are same, but the fluid is more = viscous, therefore it takes more power from the engine to turn the pump, = and this extra energy is converted to heat. Bill Schertz KIS Cruiser # 4045 ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Monday, September 27, 2004 12:05 PM Subject: [FlyRotary] Re: Oil viscosity I think it is a mystery, and not heating by the pump - for two = reasons: 1) The heat load added by the pump has to VERY small compared = to the heat load coming from the engine, 2) The pressure the pump is = working against is basically the same as determined primarily by the = pressure regulator valve (as confirmed by his data), and the flow is = roughly the same because it is positive displacement pump. Al -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Bill Schertz Sent: Monday, September 27, 2004 8:33 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Oil viscosity Some thoughts on Rusty's improved cooling with the lower viscosity = oil. If you recall, there was an earlier discussion about drilling out = the oil passage in the iron end plate and taking the oil from there. I = believe Ken Welter did this, and obtained about a (15 degree?) = improvement in oil temperature. The only way this effect could be = possible is that the pump is working less hard, and there is therefore = less heat being generated in the oil by the action of the pump. This could relate to Rusty's experience, namely a lower viscosity oil = would require less power input to pump, and the heating due to the pump = would be less. Add to this the beneficial effect of lower viscosity = improving the heat rejection in the heat exchanger, and I can believe = the improvement is related to viscosity change. There is an interesting NACA paper "Cylinder-Temperature Correlation = of a single cylinder liquid cooled engine" published in 1946 where they = studied the effects of flow rate and coolant properties on cooling = effectiveness. The correlation of lots of data where they varied the = ethylene glycol concentration from 0 to 97% allowed them to determine = the relative effects of heat capacity, thermal conductivity, and = viscosity of the cooling medium. They found that high specific heat, = high thermal conductivity, and low viscosity are desirable = characteristics of a good cooling fluid. In order of importance,=20 Thermal conducivity (k) > heat capacity (Cp) > viscosity (v). Rusty is not changing k or Cp with the lighter weight oil, and the = viscosity change only affects the heat transfer effect slightly, so I am = left with the conclusion that it is the decrease in absorbed work that = makes the biggest difference. Bill Schertz KIS Cruiser # 4045 ----- Original Message ----- From: Russell Duffy [mailto:13brv3@bellsouth.net] Sent: 9/26/2004 4:39:16 PM To: flyrotary@lancaironline.net Subject: [FlyRotary] Re: Oil viscosity 5W30 seems a bit low. > > I was thinking the same thing. Leon, will an extremely light oil be able to keep the seperation between the bearings and shaft? On the other hand, will it 'wet' the walls of the cooler better and thereby transfer heat more efficiently? Since when it 30 weight oil is "extremely light"? You might call it = extremely standard, or extremely normal :-) As I understand it, the = first number is the cold rating, which is just for cold starting, so it = doesn't have any effect on normal operation.=20 BTW, I made about 3 trips around the airport (on the ground of = course), and just made it to 140 degrees. I'm convinced it's cooling = much better with the lighter (though not extremely light ) oil. Can't = wait to fly it, but next Sunday is the earliest possible opportunity, = and probably more like the next weekend.=20 Rusty (Airbike project for sale cheap on eBay now, gotta make room in = the garage) ------=_NextPart_000_000F_01C4A4BB.D7A79420 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
I realize flow and pressure are same, = but the fluid=20 is more viscous, therefore it takes more power from the engine to turn = the pump,=20 and this extra energy is converted to heat.
 
 
Bill Schertz
KIS Cruiser # 4045
----- Original Message -----
From:=20 Al = Gietzen=20
Sent: Monday, September 27, = 2004 12:05=20 PM
Subject: [FlyRotary] Re: Oil=20 viscosity

I think = it is a=20 mystery, and not heating by the pump =96 for two reasons: 1) The heat = load added=20 by the pump has to VERY small compared to the heat load coming from = the=20 engine, 2) The pressure the pump is working against is basically the = same as=20 determined primarily by the pressure regulator valve (as confirmed by = his=20 data), and the flow is roughly the same because it is positive = displacement=20 pump.

 

Al

 

 -----Original=20 Message-----
From:=20 Rotary motors in=20 aircraft=20 [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Bill Schertz
Sent: Monday, = September=20 27, 2004 8:33=20 AM
To: Rotary = motors in=20 aircraft
Subject: [FlyRotary] Re: Oil=20 viscosity

 

Some thoughts on Rusty's = improved cooling=20 with the lower viscosity oil.  If you recall, there was an = earlier=20 discussion about drilling out the oil passage in the iron end plate = and taking=20 the oil from there. I believe Ken Welter did this, and obtained about = a (15=20 degree?) improvement in oil temperature. The only way this effect = could be=20 possible is that the pump is working less hard, and there is therefore = less=20 heat being generated in the oil by the action of the=20 pump.

 

This could relate to Rusty's = experience,=20 namely a lower viscosity oil would require less power input to pump, = and the=20 heating due to the pump would be less. Add to this the beneficial = effect of=20 lower viscosity improving the heat rejection in the heat exchanger, = and I can=20 believe the improvement is related to viscosity=20 change.

 

There is an interesting NACA = paper=20 "Cylinder-Temperature Correlation of a single cylinder liquid cooled = engine"=20 published in 1946 where they studied the effects of flow rate and = coolant=20 properties on cooling effectiveness. The correlation of lots of data = where=20 they varied the ethylene glycol concentration from 0 to 97% allowed = them to=20 determine the relative effects of heat capacity, thermal conductivity, = and=20 viscosity of the cooling medium.  They found that high specific = heat,=20 high thermal conductivity, and low viscosity are desirable = characteristics of=20 a good cooling fluid. In order of importance,

 

Thermal conducivity (k) > = heat=20 capacity (Cp) > viscosity (v).

 

Rusty is not changing k or Cp = with the=20 lighter weight oil, and the viscosity change only affects the heat = transfer=20 effect slightly, so I am left with the conclusion that it is the = decrease in=20 absorbed work that makes the biggest = difference.

 

Bill Schertz
KIS Cruiser # = 4045

 

 

----- Original Message=20 -----

From: Russell = Duffy=20 [mailto:13brv3@bellsouth.net]

Sent: 9/26/2004 = 4:39:16=20 PM

To:=20 flyrotary@lancaironline.net

Subject: = [FlyRotary] Re:=20 Oil viscosity

 

5W30 seems a bit low.
>
>
I = was=20 thinking the same thing. Leon, will an
extremely light oil be able = to keep=20 the seperation
between the bearings and shaft? On the other = hand,
will=20 it 'wet' the walls of the cooler better and
thereby transfer heat = more=20 efficiently?

 

Since=20 when it 30 weight oil is "extremely light"? You might call it = extremely=20 standard, or extremely normal :-) As I understand it, the first number = is the=20 cold rating, which is just for cold starting, so it doesn't have any = effect on=20 normal operation.

 

BTW, I=20 made about 3 trips around the airport (on the ground of course), and = just made=20 it to 140 degrees. I'm convinced it's cooling much better with the = lighter=20 (though not extremely light ) oil. Can't wait to fly it, but next = Sunday is=20 the earliest possible opportunity, and probably more like the next = weekend.=20

 

Rusty=20 (Airbike project for sale cheap on eBay now, gotta make room in the=20 garage)

 

 

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