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Date: Tue, 11 Nov 2008 18:58:27 -0700
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Oil Coolers - OFF TOPIC - hailing Lynn Hanover!
Message-Id: <20081111185827.c42940da.bob@bob-white.com>
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OK, understood.  I would be surprised if BMW designed the oil cooler so
that it didn't work very well, but I don't know enough about their
design to explain it either.  I have a K75.  I'll have a look at it
tomorrow to see if it's the same setup.

Bob W.

On Tue, 11 Nov 2008 19:20:22 -0500
"Thomas Jakits" <rotary.thjakits@gmail.com> wrote:

> Hi Bob,
> 
> the coolers on the BMWs have bottom inlet and bottom outlet.
> What bothers me is the bottom outlet.
> Although the oil is under pressure - if you do the numbers there maybe still
> up to a 1/4 of the cooler useless with a air pocket doing only damping
> duties...
> 
> As with your radiator, with a top outlet the air will always be on top and
> pushed out the outlet.
> Once back in the oil lines, viscosity and speed will take care of the air
> and purge it from the system.
> Once the air is trapped it will not move anymore. The oil below the air
> cushion will flow through the cooler, but the air has no more chance to get
> pushed out, because ther is no more oil going to the top rows.
> 
> Of course if the inlet tank is small, no thermostat in the system, full flow
> system, there is a small chance that most of the air gets pushed out!
> Depends if the oil volume/mass that goes *initially* through the upper most
> rows of the cooler has enough inertia/speed to trapp the air and pull it
> along on the way down and out the bottom outlet ......
> 
> That is essentially my question!!
> 
> Is oil that much different than water that the outlet position does not
> matter??
> 
> I hope Lynn can shed some light on this - racing and all!!
> It would also be interesting if someone has actual test/trial data:
> # transparent tanks ....
> 
> Thomas/thjakits
> 
> 
> 
> 
> On Tue, Nov 11, 2008 at 6:30 PM, Bob White <bob@bob-white.com> wrote:
> 
> > The way I was visualizing it, if you have a bottom inlet then you
> > would have a top outlet and vice versa.  I agree with what you are
> > saying, but suspect you might get better distribution through the
> > exchanger if the input were on the bottom.
> >
> > I learned the ineffectiveness of plumbing a heat exchanger wrong with
> > the heater core on my old '52 Ford.  Since radiators outlets were on
> > the bottom and inlets on the top, I reasoned that the heater core
> > should be the same.  As soon as the water level in the system got a
> > little low (and it always did), the heater would only blow cold air.
> > After switching the hoses around, water going in the bottom would
> > always fill the core to the top outlet and the heater worked just fine
> > even with low water in the cooling system.
> >
> > Bob W.
> >
> > On Tue, 11 Nov 2008 18:00:32 -0500
> >  "Thomas Jakits" <rotary.thjakits@gmail.com> wrote:
> >
> > > Hi Bob,
> > >
> > > thanks for your reply!
> > >
> > > In both installations the oil-cooler is above the oil level by a good
> > > margin.
> > >
> > > In my opinion the inlet position is not the critical issue, but the
> > outlet.
> > >
> > > As the oil slows down considerable in the inlet tank, it may (or not)
> > loose
> > > the ability to push all the air out in front of it.
> > > If at the initial filling of the cooler after start-up (or opening of the
> > > thermostat) air gets trapped at the top of the cooler, this air never
> > gets
> > > pushed out, just compressed to oil pressure values.
> > > With a top outlet, the air has no choice but leave the cooler through the
> > > outlet....
> > >
> > > Am I way out there ?????
> > >
> > >
> > > thjakits
> > >
> > > On Tue, Nov 11, 2008 at 2:46 PM, Bob White <bob@bob-white.com> wrote:
> > >
> > > > Hi Thomas,
> > > >
> > > > If the oil cooler is below the oil level in the bike, I don't think top
> > > > or bottom inlet will matter too much.  If it's above the oil level in
> > > > the pan, then bottom inlet will ensure the cooler is always full of
> > oil.
> > > >
> > > > My 2 cents and that's probably more than it's worth. :)
> > > >
> > > > Bob W.
> > > >
> > > > On Tue, 11 Nov 2008 14:27:00 -0500
> > > > "Thomas Jakits" <rotary.thjakits@gmail.com> wrote:
> > > >
> > > > > Hi all,
> > > > >
> > > > > I know this is a rotary and aviation list, but there is a lot of
> > cooling
> > > > > going on here, so I just dare to ask a OFF TOPIC - no pics, so it
> > should
> > > > > load quick too :)
> > > > >
> > > > > I would like to ask specifically* Lynn Hanover*, but if anyone else
> > knows
> > > > > something too, please let me know!
> > > > >
> > > > > Hopefully soon I will start to restore my 79 R100S BMW bike.
> > > > > It does not have an oil cooler yet, but it will when I am done with
> > it.
> > > > >
> > > > > My question regards the correct orientation of the cooler.
> > > > >
> > > > > To my knowledge ALL BMW airhead OEM oil cooler installations are with
> > the
> > > > > connections at the bottom of the cooler.
> > > > > I have a mangled specimen off a GS at home - it seems to be a 6-row,
> > > > single
> > > > > pass cooler.
> > > > >
> > > > > I posted this question on ADV, but got no clear answer.
> > > > > I am  still waiting for a reply from one member who posted a
> > reference to
> > > > a
> > > > > cooler manufacturer that says cooler orientation does not matter (in
> > > > > reference to the position of the connections .....)
> > > > >
> > > > > # My concern is, that if the outlet is at the bottom of the cooler,
> > there
> > > > > may be a air cushion trapped in the upper part of the cooler -
> > depending
> > > > on
> > > > > the oil pressure and heat, this may cause a significant loss of
> > cooling
> > > > > capacity - question: Right or Wrong???
> > > > >
> > > > >
> > > > > Here the link to the post on ADV if you care to discuss (Beware, if
> > > > you're
> > > > > used to the polite, friendly and helping attitude on this list, you
> > may
> > > > > encounter a somewhat different trend on other lists, ..... at times!
> > ADV
> > > > in
> > > > > general is a great place, just now and then one encounters ridicule
> > of
> > > > > varying degrees.....)
> > > > >
> > > > > http://www.advrider.com/forums/showthread.php?t=400352    ("Oil
> > Cooler
> > > > > Orientation")
> > > > >
> > > > > All I really want is to confirm or refute my view!
> > > > >
> > > > >  Also, most "performance installations" Sport, Racing - seem to
> > support
> > > > my
> > > > > suggestion - outlet on top....
> > > > >
> > > > > http://www.advrider.com/forums/showthread.php?t=328831
> > > > > http://www.advrider.com/forums/showthread.php?t=399841
> > > > >
> > > > >
> > > > > Any experience, data, tests  -   you guys/gals?
> > > > >
> > > > > Next question: Again orientation of the cooler.
> > > > >
> > > > > On this list I learned a lot about ducting. Obviously here we are
> > > > generally
> > > > > talking about 35-40 kts at a minimum or at least a prop blast on the
> > > > ground.
> > > > > On the bikes (I limit this discussion to BMW airheads) they are
> > installed
> > > > > vertical in front of the engine or on the right side on top of a
> > crashbar
> > > > in
> > > > > front of the cylinder.
> > > > > Generally there are no ducts - one had a "fairing" for optics at some
> > > > time.
> > > > >
> > > > > Check the following thread and you will see either installation at
> > some
> > > > > point.
> > > > >
> > > > > http://www.advrider.com/forums/showthread.php?t=51879   (Plenty of
> > GS
> > > > > installations right away, a center one is on a yellow bike nearly all
> > the
> > > > > way at the bottom of the 1st page....)
> > > > >
> > > > >
> > > > > According to my wisdom gathered  on this list, either installation is
> > > > about
> > > > > useless:
> > > > >
> > > > > # Most of the cooling air would go around the cooler instead of
> > through
> > > > > # Speeds are of course slower than with airplanes, but the cooling is
> > > > worse
> > > > > when standing still or in stop and go.
> > > > > # Cooling would be done mainly by radiation in this situation.
> > Question:
> > > > > True/False?
> > > > >
> > > > > Question: Could cooling be improved in this stop/go situation by
> > > > installing
> > > > > the cooler at an angle (30-45 deg) so there would be some convective
> > > > action,
> > > > > once the heated air leaves the back of the cooler?
> > > > >
> > > > > I know, there is probably not much action.....
> > > > >
> > > > > My plan (pending replies...) is to have me a cooler custom welded (Ed
> > > > > Klepeis  ?), still need to guestimate the size: 2-pass, inlet at the
> > > > bottom,
> > > > > outlet at the top.
> > > > > Install with a 30 degree angle (top forward) and make a small
> > alu-duct.
> > > > > Question how long should the the duct be at a minimum in front of the
> > > > > cooler?
> > > > > It will probably not be a real duct, but rather a guide - aesthetics
> > are
> > > > of
> > > > > course of some importance on the bike!
> > > > >
> > > > >
> > > > > Any airheads on this list?
> > > > >
> > > > > Any suggestions?
> > > > >
> > > > >
> > > > > At the end my 100S lived its life without a cooler, but Austrian airs
> > are
> > > > > way cooler than Panamanian, so a cooler she will get! :)
> > > > >
> > > > >
> > > > > Thanks for your time and suggestions!
> > > > >
> > > > > thjakits
> > > > >
> > > >
> > > >
> > > > --
> > > > N93BD - Rotary Powered BD-4 - http://www.bob-white.com
> > > > 3.8 Hours Total Time and holding
> > > > Cables for your rotary installation - http://roblinstores.com/
> > > >
> > > > --
> > > > Homepage:  http://www.flyrotary.com/
> > > > Archive and UnSub:
> > > > http://mail.lancaironline.net:81/lists/flyrotary/List.html
> > > >
> > >
> >
> >
> > --
> >  N93BD - Rotary Powered BD-4 - http://www.bob-white.com
> > 3.8 Hours Total Time and holding
> > Cables for your rotary installation - http://roblinstores.com/
> >
> > --
> > Homepage:  http://www.flyrotary.com/
> > Archive and UnSub:
> > http://mail.lancaironline.net:81/lists/flyrotary/List.html
> >
> 


-- 
N93BD - Rotary Powered BD-4 - http://www.bob-white.com
3.8 Hours Total Time and holding
Cables for your rotary installation - http://roblinstores.com/