Even though my engine now runs cooler than I’d like at cruise and descent; I’m hesitant to put a thermostat in the engine.  Measurements I made on the dyno showed that installing the thermostat reduced the coolant flow rate by nearly 1/3 (31%) at operating conditions typical of climb.  That would also reduce the cooling capacity some, resulting in higher temps.  I like that my coolant stays below about 200 - 205 on climbout on a 90F day, so I don’t want to change that.

 

The other factor of course is that the engine would get up to 180F much quicker.  As it is, I can start up, listen to ATIS, take my time taxing between hangars, down to the runup area, do the runup tests – and only then have the temp up to about 180.  It may get up to 190 by wheels up, but then it stabilizes during climb, and will begin to drop as I reduce power.

 

The best way to increase cruise temps is to reduce air flow. 

 

I do have an in-line thermostat in the line to my second radiator, but I had drilled a couple small holes to insure some flow.  I’m going to replace that with one with only the air bleed hole, and see if the coolant temp stays at/above the 170 thermostat temp.

 

Al G

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Steve Brooks
Sent: Sunday, August 10, 2008 3:46 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: 2nd flight on the new cooling system

 

Paul,

That is a good point, and something that I had not considered before.  Putting the thermostat back in, wouldn't be an easy task.  I removed the plastic / fiber, whatever it is made of portion where the thermostat resided, and used a 1/4" aluminum plate in it's place.  That plate has an AN16 fitting welded to it, and also has two  1/4 NPT  holes in it to hold sensors.

 

They probably make an in-line thermostat I assume, so that would probably be an option.

 

Steve Brooks

 

 

-----Original Message-----

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of fpbjr2001@yahoo.com

Sent: Saturday, August 09, 2008 7:40 PM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: 2nd flight on the new cooling system

 

steve

   sounds great. something to think about. if get to a point where you think you have enough cooling a 170-180 degree thermostat would be nice to stabilize the system. as you know i have run a thermostat since day one.

                       paul brannon

 

 

--- On Sat, 8/9/08, Steve Brooks <cozy4pilot@gmail.com> wrote:

 

> From: Steve Brooks <cozy4pilot@gmail.com>

> Subject: [FlyRotary] 2nd flight on the new cooling system

> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

> Date: Saturday, August 9, 2008, 1:58 PM

> I took the Cozy up this morning for the 2nd flight on the

> new cooling

> system.  The OAT was 3 or 4 degrees warmer than the first

> flight, as it was

> 79 F when I took off.

> This time, I turned the cooling fan on while I was taxiing

> out to the

> runway.  After the  taxi and pre-flight checks, the oil was

> 135 F and the

> coolant was still reading pretty low.  Maybe 115 to 120 or

> so.  It is a

> little hard to read the analog gauge down on the low end of

> the scale.

>

> I took off and climbed up to about 1300 FT AGL, at which

> time I pulled the

> throttle back some and continued a cruise climb.  The

> coolant was showing

> about 190F, and I didn't think to check the oil

> temperature.  Oil

> temperature has not been my issue.  It has always been the

> coolant.  The

> coolant temperature did still increase a little, even at

> the reduced power,

> but just up to 200 F.  I was close to a low cloud layer at

> about 1800 AGL,

> so I throttle back some more and dropped the nose to level

> flight.  I also

> turned off the cooling fan to see what the temperature

> would do on it's own.

> The temperature steadily dropped to about 180 degrees

> within just a few

> minutes, and then stabilized there.

>

> I cruised around for a little while, flew over my house and

> circled it once,

> and then headed back to the airport.  With the low cloud

> layer that had

> moved in, I really didn't know if it was going to clear

> out or get thicker,

> so I flew the 5 minutes back to the airport, and made a

> normal landing.  As

> I was ready to throttle back to descend about 800 feet to

> pattern altitude,

> and quick check of the coolant temperature showed about 160

> degrees.  Not

> bad at all, although I was probably flying at about 60%

> power.  Still, it

> would have not been nearly that low before the new cooling

> system.

>

> Once I landed and was clearing the runway, I checked the

> temperatures again,

> and the coolant was less then 140 degrees after the glide

> in to land.  Since

> I planned to wash the plane, and sometimes it starts hard

> after getting heat

> soaked sitting after a run, I turned on the cooling fan

> while a taxied over

> to the where the wash area is.  After washing the plane, it

> started up

> pretty easily, so I guess that worked out also.

>

> So far so good.  I like what I see so far on the radiator,

> and the cooling

> fan definitely gives me a lot more options.

>

> Steve Brooks

> Cozy N75CZ

> 13B turbo to read the an

 

 

    

 

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