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I have tried two different oil-water cooling schemes and I could see the
potential advantages. When using the 83-84 (I think) Mazda
oil/water cooler it was not quite adequate as the oil temp was always near
redline in-flight, BUT! I was using the same radiators and had no air
inlet for the oil cooling thus I was using far less CFM of air to do the
engine cooling (the key to less cooling drag). The only shortcoming
was that there was simply too few square inches of heat exchanger area to get
the oil temp down to near the engine water temp. To do this takes a
much larger oil/water exchanger and that is what Art at Propelled Engineering
was using on his FWF demo engine. It looks like it has 6 - 10 times the
area of the Mazda oil/water cooler. In ground runs, the oil tracked
the water temp within a few degrees so I am hopeful that it will work well in
flight.
Tracy
----- Original Message -----
Sent: Monday, April 30, 2007 8:52
AM
Subject: [FlyRotary] Re: oil
coolers
Hi Ed,
I have no actual experience with a oil/coolant
heat exchanger. I looked at
them and decided that since I had room
for an oil cooler (and already owned
one) that a oil/coolant heat
exchanger would not provide any benefit.
Theoretically, the heat
transferred from the oil to the coolant raises the
temperature of the
coolant compared to the incoming cooling air - thus
making that
arrangement thermodynamically more efficient due to the
increased
temperature difference. On the other hand, this is somewhat
offset by the fact that by raising the temp of the coolant the temperature
difference between the oil and its cooling agent (the water) will be
lessened. Which in turn is offset by the fact that a lb of water can
carry
more heat than a lb of air {:>).
However, I think the main
advantage of the oil/coolant heat exchanger is:
1. Give you
more freedom in installation in that you can put the exchanger
just about
anywhere without worrying about how to get cooling air to it.
2.
Eliminates the need for a separate oil cooler
Since you are dumping the
oil heat into the coolant this will generally
necessitate a large radiator
system to handle the additional heat load.
Since I have no experience
with the units, I am unaware of their most common
failure mode.
Personally, a case could be made that without airflow to an
oil cooler you
are better protected against rocks ect, damaging it. If you
have a
leak in the lubrication system your engine is going to seize sooner
rather
than later. Leaks in the coolant system will result in engine damage
but at least two case shows that the overheated engine will still continue
to function well enough, long enough to get you to a safe
landing.
I think your NASCAR contact can probably provide better input
on the pros
and cons of using one.
Ed
----- Original
Message -----
From: "Ed Klepeis" <techwelding@comcast.net>
To:
"Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent:
Sunday, April 29, 2007 10:06 PM
Subject: [FlyRotary] Re: oil
coolers
> Dear Ed
> What is
your opinion on oil coolers air/oil or water/oil. I know art
> is
running a water cooler oil cooler and it works fine my concerns are if
> you should lose water cooling there goes the whole system water and
oil.
> At least if you have your oil cooling system air cooled you have
some
> cooling of the eng to get you safely on the ground. Also less
lines to
> hook up without the water going to the oil cooler.I have a
meeting with my
> neighbor Waltrip the nascar fellows cheif mech to
talk this subject over
> will be interesting to see what the nasca boys
say and use. I can build it
> either air/oil or water/oil. What are the
opinions out there.thanks
>
> Regards
>
> Ed
Klepeis
>
>
> ----- Original Message -----
> From:
"Ed Anderson" <eanderson@carolina.rr.com>
>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
>
Sent: Sunday, April 29, 2007 7:26 PM
> Subject: [FlyRotary] Re: Throttle
body size
>
>
>> Hi Buly,
>>
>> I have
tired throttle bodies as big as 75mm, I went back to a 65 mm
>>
Mustang Throttle body. Here is what I found.
>>
>> The
larger throttle body provided no measurable increase in power
>> produced - in fact, the power actually went down as my static
fell 200
>> rpm. I did find that suddenly opening the large 75mm TB
would cause the
>> engine to bog and hesitate for a second. It
was suggested that I push
>> the throttle in more slowly, well,
Scotty, when I want full power I want
>> it
NOW!
>>
>> In any case, I now fly and have flown with the 65
mm for 3 years. I can
>> turn 6000 rpm static on a standard
day and upto 6200 static on those
>> wonderful cold mornings. I can
shove the throttle in as fast as I can
>> and there is no bog
or hesitation.
>>
>> That is what my experience has
been. For a full up all out race engine,
>> I am certain
Paul's suggestion has merit, but for our usage, I did not
>> find a
large TB provided any improvement and actually make flying less
>>
pleasant.
>>
>> Ed
>>
>> ----- Original
Message -----
>> From: "Bulent Aliev" <atlasyts@bellsouth.net>
>>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
>>
Sent: Sunday, April 29, 2007 6:05 PM
>> Subject: [FlyRotary] Throttle
body size
>>
>>
>>>I originally planned and
tried TA set up on my Cosmo 13B. Soon after the
>>>first
few flights removed the turbo and vent NA. At the time did not pay
>>>much attention on the throttle body size, counting on
the turbo to make
>>>up for any losses. Today I measured
the inside opening of the TB and was
>>>surprised to find
it was only 60mm. This is rather small. Paul Lamar on
>>>his visit also said I should get a bigger one. I wander
what size TB
>>>other people are using, or any comments and
suggestions on the matter
>>>will be
helpful.
>>>
>>>
Buly
>>>
>>>
>>>
>>>
>>>
>>>
--
>>> Homepage: http://www.flyrotary.com/
>>>
Archive and UnSub:
>>> http://mail.lancaironline.net:81/lists/flyrotary/List.html
>>
>>
>>
--
>> Homepage: http://www.flyrotary.com/
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>>
>
>
>
>
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