REFLECTOR: High Oil Temps

[Brian Michalk]

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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