Return-Path: Received: from [65.54.241.211] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2.3) with ESMTP id 435071 for flyrotary@lancaironline.net; Tue, 28 Sep 2004 04:22:32 -0400 Received-SPF: none receiver=logan.com; client-ip=65.54.241.211; envelope-from=lors01@msn.com Received: from hotmail.com ([65.54.168.111]) by hotmail.com with Microsoft SMTPSVC(5.0.2195.6713); Tue, 28 Sep 2004 01:22:00 -0700 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Tue, 28 Sep 2004 01:22:00 -0700 Received: from 4.171.174.101 by bay3-dav7.bay3.hotmail.com with DAV; Tue, 28 Sep 2004 08:21:43 +0000 X-Originating-IP: [4.171.174.101] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Oil viscosity Date: Wed, 29 Sep 2004 04:22:43 -0400 MIME-Version: 1.0 X-Mailer: MSN Explorer 7.02.0011.2700 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0001_01C4A5DB.F758F680" Message-ID: X-OriginalArrivalTime: 28 Sep 2004 08:22:00.0550 (UTC) FILETIME=[3A237060:01C4A534] Return-Path: lors01@msn.com ------=_NextPart_001_0001_01C4A5DB.F758F680 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Very interesting findings Rusty, I'll be very interested in the flight te= st results. Another possibility of where the temp increase (with higher = viscosity) is coming from is the gear drive. The good thing about planet= ary drives is the very high strength from all those gear teeth in mesh. = The bad thing is the higher losses from shearing the oil in all those gea= r teeth. I didn't think the difference would be that much but I never t= ested. I've always used 15-50 Mobile 1 but will try a batch of 5-30 on t= he next oil change. Synthetic is my choice because of the much higher sh= ear strength. Tracy (running the generator) ----- Original Message ----- From: Al Gietzen Sent: Monday, September 27, 2004 1:36 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Oil viscosity I think it is a mystery, and not heating by the pump =E2=80=93 for two re= asons: 1) The heat load added by the pump has to VERY small compared to t= he heat load coming from the engine, 2) The pressure the pump is working = against is basically the same as determined primarily by the pressure reg= ulator 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 B= ehalf 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 K= en 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 wou= ld require less power input to pump, and the heating due to the pump woul= d be less. Add to this the beneficial effect of lower viscosity improving= the heat rejection in the heat exchanger, and I can believe the improvem= ent 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 studi= ed the effects of flow rate and coolant properties on cooling effectivene= ss. The correlation of lots of data where they varied the ethylene glycol= concentration from 0 to 97% allowed them to determine the relative effec= ts of heat capacity, thermal conductivity, and viscosity of the cooling m= edium. They found that high specific heat, high thermal conductivity, an= d 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 viscos= ity change only affects the heat transfer effect slightly, so I am left w= ith the conclusion that it is the decrease in absorbed work that makes th= e 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 extre= mely standard, or extremely normal :-) As I understand it, the first numb= er is the cold rating, which is just for cold starting, so it doesn't hav= e any effect on normal operation. =20 BTW, I made about 3 trips around the airport (on the ground of course), a= nd just made it to 140 degrees. I'm convinced it's cooling much better wi= th the lighter (though not extremely light ) oil. Can't wait to fly it, b= ut next Sunday is the earliest possible opportunity, and probably more li= ke the next weekend. =20 Rusty (Airbike project for sale cheap on eBay now, gotta make room in the= garage) ------=_NextPart_001_0001_01C4A5DB.F758F680 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
Very interesti= ng findings Rusty, I'll be very interested in the flight test results.&nb= sp; Another possibility of where the temp increase (with higher viscosity= ) is coming from is the gear drive.  The good thing about planetary = drives is the very high strength from all those gear teeth in mesh. = The bad thing is the higher losses from shearing the oil in all those ge= ar teeth.   I didn't think the difference would be that much bu= t I never tested.  I've always used 15-50 Mobile 1 but will try a ba= tch of 5-30 on the next oil change.  Synthetic is my choice because = of the much higher shear strength.
 
Tracy&nbs= p; (running the generator)
 
----- = Original Message -----
From: Al Gietzen
Sent: Monday, September 27, 2004 1:36 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Oil viscosity<= /DIV>
 

I think it is a mystery, and not heating= by the pump =E2=80=93 for two reasons: 1) The heat load added by the pum= p 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 determi= ned primarily by the pressure regulator valve (as confirmed by his data),= and the flow is roughly the same because it is positive displacement pum= p.

 

Al

 

 -----Origina= l Message-----
From: <= /SPAN>Rotary motors in aircraft [ma= ilto:flyrotary@lancaironline.net] On= Behalf Of Bill Schertz
Monday, September 27, 2004 8:33 AM<= BR>To: Rotary motors in aircraft=
Subject: [FlyRotary] Re: Oil viscosity

 

<= FONT face=3D"Times New Roman" size=3D3>So= me thoughts on Rusty's improved cooling with the lower viscosity oil.&nbs= p; 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 believ= e Ken Welter did this, and obtained about a (15 degree?) improvement in o= il temperature. The only way this effect could be possible is that the pu= mp is working less hard, and there is therefore less heat being generated= in the oil by the action of the pump.

 

This could rela= te 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 rejec= tion 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 engi= ne" published in 1946 where they studied the effects of flow rate and coo= lant properties on cooling effectiveness. The correlation of lots of data= where they varied the ethylene glycol concentration from 0 to 97% allowe= d them to determine the relative effects of heat capacity, thermal conduc= tivity, and viscosity of the cooling medium.  They found that high s= pecific heat, high thermal conductivity, and low viscosity are desirable = characteristics of a good cooling fluid. In order of importance, <= /FONT>

= <= /SPAN> 

Thermal conducivity (k) > heat capacity (Cp) > vis= cosity (v).

 

<= SPAN style=3D"FONT-SIZE: 12pt">Rusty is not changing k or Cp with the lig= hter 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.

=  

= B= ill Schertz
KIS Cruiser # 4045

 

 

----- Ori= ginal Message -----

From: Rus= sell Duffy [mailto:13brv3@bellsouth.net]

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

To: flyrotary@lanc= aironline.net

Subject: [FlyRotary] Re: Oil = viscosity

5W30 seem= s 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 "extremel= y light"? You might call it extremely standard, or extremely normal :-) A= s 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.

 

BTW, I made about 3 trips= around the airport (on the ground of course), and just made it to 140 de= grees. I'm convinced it's cooling much better with the lighter (though no= t extremely light ) oil. Can't wait to fly it, but next Sunday is the = earliest possible opportunity, and probably more like the next weekend. <= /SPAN>

 

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

=  

 

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