REFLECTOR: High Oil Temps
steve korney
s_korney at hotmail.com
Mon Jun 24 13:08:10 CDT 2013
If you vent into the low pressure side it's OK...
Steve
Date: Mon, 24 Jun 2013 12:57:51 -0500
From: michalk at awpi.com
To: bjb3013 at yahoo.com; reflector at tvbf.org
Subject: Re: REFLECTOR: High Oil Temps
What would happen if you just vented
into the engine compartment?
On 6/24/2013 9:52 AM, Brent Bourgeois wrote:
I did lots of
measuring in flight and found inlet area is not nearly as
important as exit area. Most have way to much inlet and the
largest portion of the air never makes it through the cooler. I
was never successful cramming more air in the cooler and
achieved real good results sucking it out. ( that's for
cylinder cooling also) A ramp or lip in front of the exit can be
used to actually make the air behind the cooler much lower
pressure than in front. My coolers are good for about 15 degrees
each. The best thing I did was to move the oil lines each to
their own duct and add a 1 inch hole inlet and a 1.5 x3 reverse
ramp on the duct exit 6 inches before the firewall. There is
more cooling available in those 2 long aluminum lines than most
coolers.
Cool the oil and the CHT problem will take care of it
self.
Call if I
can help
985-785
eight two nine 9
Brent
N61VB
From: steve
korney <s_korney at hotmail.com>
To:
Reflector Reflector <reflector at tvbf.org>
Sent:
Sunday, June 23, 2013 10:09 PM
Subject:
Re: REFLECTOR: High Oil Temps
It will take about 8 square
inches of inlet to get enough air to each oil
cooler at 150 knots...
Steve
Date: Sun, 23
Jun 2013 21:35:47 -0500
From: michalk at awpi.com
To: reflector at tvbf.org
Subject: Re: REFLECTOR: High Oil Temps
They
are the stock coolers, about 4.5" x 6" face
area. The inlet duct is not a real NACA scoop.
I extended the face of the cooler to the skin of
the plane. Once I have enough hours, I will
experiment with closing down the aft lip of the
inlet, making a diverging duct.
I've already closed down my armpit scoops a
little based upon oil flows on the fuselage. I
have variable armpit scoops, but at the moment
they are only ground adjustable.
On 06/23/2013 09:29 PM, steve korney wrote:
Hey Brian...how big
are the oil coolers and how much inlet scoop
area do you have...?
Steve
> Date: Sun, 23 Jun 2013 17:42:44
-0500
> From: michalk at awpi.com
> To: reflector at tvbf.org
> Subject: REFLECTOR: High Oil Temps
>
> Today I had a very good test flight.
>
> I've been battling high CHT and oil
temps, and made the decision to
> increase my prop pitch for todays
flight to bring down RPM's. That made
> a marked difference in CHT temps, and I
could fly without redlining the
> CHT's.
>
> Now, I still have high oil temps. My
oil cooler arrangement is two oil
> coolers in the nose in parallel. The
secondary cooler has a radiator
> fan attached with a flapper valve that
doubles for ground operations and
> cabin heat. Needless to say, the fan
doesn't do a very good job, and I
> think is the source of my high oil
temps.
> For this thought game, assume two
identical oil coolers with equal oil
> flow in parallel. This means that each
cooler gets 50% of the oil.
> Now, assume no cooling air flows
through one of the coolers. The result
> is that half the oil is cooled, and the
other half gets returned at the
> same temperature it began. The result
is that I get 50% of the cooling
> that's available.
>
> What I've done in the meantime is I've
capped off my second cooler. I
> have not flown with this configuration,
and will do so this coming
> weekend. I really do think this will
get me within the temperature
> ranges to get around to some serious
flight testing.
>
> Now, the real question:
> Given two identical coolers that flow
equal parts oil, and also have
> equal amounts of airflow, is it better
to plumb them in series or in
> parallel for maximum heat rejection? It
seems to me that parallel is
> like having more frontal cooler area,
while in series would be like
> having a thicker cooler, with the
larger frontal area being the more
> efficient design.
>
> Does anyone have any info on this?
>
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