George,

Actually the fan is in between the air inlet, and the radiator, so it is pushing air through the radiator.  This is a pusher airplane, and the inlet scoop is what they call a NACA scoop, but it also has an extended lip, so not a true NACA. 

Steve

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of George Lendich
Sent: Sunday, August 03, 2008 8:22 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Back in the air

Steve,

Thanks for the photo and reply, yep it's a large fan, that's for sure - I assume it's sucking on the Rad.

I was wondering if it wouldn't be better if a large fan was used and it was blowing on the rad, and it was free wheeling when turned off - if ( in that case) the restriction would be less.

George ( down under)

George,

I had considered that.  I would assume that there is definitely some restriction caused by the fan, but I think that the benefits during extended ground operation, and during climb, probably outweigh the downside.  But, you are right.  The only way to see how much, is to remove it, and try a takeoff and climb without the fan.  It would probably take about an hour to remove the fan and get the plenum and cowlings reinstalled.

I will most likely do this, but I think that I will fly it some more first, and get a good benchmark on the current set up.  Plus after 3 ½ months of down time, I just want to fly it some.

Regards,

Steve

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of George Lendich
Sent: Sunday, August 03, 2008 5:36 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Back in the air

Steve,

How large is the cooling fan, do you think it may be restrictive ( restrict air flow) in the low speed climb.

Another test would be to take out the fan and do another test and you would have a better idea of what the advantages and disadvantages are.

George (down under)

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

To: Rotary motors in aircraft

Sent: Sunday, August 03, 2008 11:33 PM

Subject: [FlyRotary] Back in the air

I’ve had my plane torn apart for about 3 ½ months rebuilding the cooling system, in between vacation, wife’s projects, and problems fitting in the radiator.  I installed a custom made radiator, replacing two evaporator cores that I was using.  The evaporator cores provided only marginal cooling for the turbo 13B, in a pusher aircraft

In order to install the new radiator, I also had to relocate almost all of the fuel system components, and I replaced the aluminum lines connecting the fuel pumps to filters to regulator with SS braided AN hose/fittings.

Due to the extensive changes, I had at least an hour, maybe hour and a half of ground testing, including four high speed taxi’s up to rotate speed. 

The new cooling system also has a cooling fan which I was able to integrate into the plenum holding the radiator.  At 95 F degrees OAT, and turning the fan on at about 190 F degrees coolant temperature, The fan maintained 180 F for 20 minutes of ground operation, including some high power testing.

This morning OAT was about 78 F, which is very good for North Carolina in August,  I wanted something less than 95 F for the first test of the new cooling system.  I did not use the cooling fan for taxi or takeoff, as I wanted to see what the cooling was without the fan.  I took of and climbed up to about 1200’ AGL.  The coolant was up to about 205, and oil at 185.  I leveled off and reduced the throttle to normal cruise power.  I watched the coolant temperature for a little while (maybe 15-20 seconds), and it seemed to stay at the 205 F reading.  I wish now that I’d been a little more patient, but I kicked on the cooling fan, and the temperature came down pretty quickly to slightly above 180 F.  I turned the fan off again and the temperature stayed right there.  I did power up and climb another 300 feet or so, but really didn’t push it too hard on the first flight.  The temperature didn’t really move too much during the brief climb.  All other systems ran perfectly and it was a very nice flight.  I did stay within gliding distance of the runway the whole flight, but based on zero squawks on this flight, the next one will be longer.

While I would like to have seen a little better performance, I was happy with the improved cooling over the old system.  Climbing to pattern altitude old the old system at today’s temperature would have been 215 – 220F.  On the next flight, I’ll take off using the cooling fan, and see what kind of numbers I get with it.  I hope to see something more in the 185-190 range, but I’ll have to see what the real number are.

Steve Brooks

Cozy MKIV N75CZ

Turbo rotary