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Steve, with equivalent OATs, if I make a full stop landing and taxi back and then take off. Under those conditions I will see around 180F for both oil and coolant by the time I am back to take off position. But, its about a quarter mile back from my point exiting runway for a taxi way and then back to take off position. So with taxi rpm my temperatures do not elevate. But, I will see 200F on the oil and perhaps 210-220F on the coolant after take off under those conditions.
While both our temps are above the nominal recommended, I have found that for short duration, there does not APPEAR to be any problem. I know Tracy encounters (or did with the old 13B) the same conditions with no apparent problems. I think we would both feel a bit more comfortable with temps that stayed below 200F (and I do use that as my max red line for oil), they only way I know to do that is to size your coolant system for climb conditions which means it will be oversized for cruise with resulting excessive drag.
My 0.02
Ed
----- Original Message ----- From: "Steve Brooks" <prvt_pilot@yahoo.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Monday, July 10, 2006 2:10 PM
Subject: [FlyRotary] Re: Temperature control
Ed,
While you're on the subject of cooling, I have a
question.
What are you temps on takeoff when you are starting
with a hot engine ?
This weekend, I flew and the OAT on takeoff was about
75 F. Climbing up about 1500 AGL my coolant was at
200 and oil about 180. Both stabilized at about 190
in level flight.
I landed to check thing out and temps on shut down
were about 160. Cooled off some on decent.
After sitting for 20 minutes or so, start up showed
about 185 and taxing to the runway. coolant was about
200 when starting the takeoff roll. Climb to about
1000 AGL had the coolant up to 220, and oil about 200.
I reduced power and continued a slow cruise climb
(about 200 fpm). The temps came down withing 2-3
minutes to below 200, and stabilized to about 190
after 5 minutes or so.
Does this seem reasonable, or are my temps running a
bit high ? I have always seemed to have temperature
problems when starting out with a hot engine.
Just wondering about what is normal.
Steve Brooks
--- Ed Anderson <eanderson@carolina.rr.com> wrote:
----- Original Message ----- From: James Maher
To: Rotary motors in aircraft
Sent: Monday, July 10, 2006 1:28 PM
Subject: [FlyRotary] Temperature control
The setup:
· Engine/Model/Year: 13B 6 port NA mixed
· Source Condition: David Atkins Rebuilt
for Aviation Application
· Modifications: Ported intakes and cooling
for 180HP
· Intake: Atkins short manifold w/TWM 48mm
Throttle body
· Exhaust: 321 SS tangential muffler
· Engine Control: RWS EC2
· Fuel Control: 4 Mazda 460cc Injectors,
pri. in block & sec in manifold
· Fuel Pumps: RWS
· Cooling System: 2 - 9"x13"GM evaporator
cores with 0.75" auto hose, stock water pump with
180F deg.-thermostat, 50/50 glycol\water mix.
· Oil System: stock 1986 oil cooler
· Installation: conventional - self built
mount
· PSRU/Re-Drive: Ross 2.85:1
· Prop: IVO Magnum 74" 45-105"pitch
in-flight adjustable
· Power: 180HP?
The issue:
On the ground, cooling stabilizes at 180-190F deg
and oil is usually 10 degrees below the cooling with
an OAT of 65-70F deg.
When running with higher OAT (75-85F deg) after
about 0.5 hours of moderate taxi runs (up to
4300RPM) the cooling temps reach 212Fdeg with the
oil about 200F deg.
The question:
Can something be done to get lower operating
temperatures without redesigning the system?
Would switching to pure water help and if so by
how much?
Would removing the thermostat help and if so by
how much?
How much change should I expect if I were to do
both?
You guys down south should have a good idea of how
best to enhance cooling.
What are your suggestions?
Thanks,
Jim Maher(Dyke Delta)
Hi James,
Welcome to the club, cooling appears to always be
the first item of business. I can not quantify the
differences those changes you propose would make.
However, a 50/50 coolant mixture has a 40% lower
specific heat than pure water alone. Meaning it
will not carry as much heat away at the same coolant
temperature. Would pure water give you 40% more
cooling - I personally doubt it, would it help, I
believe it certainly would.
I fly without a thermostat and my normal (60-70 F
OAT) temps are 160F for coolant and oil at cruise.
On a hot day, right after take off, I may hit 200F
on the oil and 220F on the coolant for a short
duration. With a thermostat, your coolant temps
are going to go right up to the thermostat limits
shortly after starting your engine - after all that
is what a thermostat does. But, still at moderate
rpm of 4300 on a 60-70F day, I would like for the
coolant and oil not to exceed 200F.
I fly without a thermostat to remove any flow
restriction as well as permitting my temps to stay
below any thermostat limit if conditions permit.
Since I get acceptable temperatures when flying I am
satisfied without a thermostat. In winter, the
temps do run a bit cool, but then I can tape off a
bit of the core and get higher temps.
Ed
That's my 0.02 worth
Ed
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