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Date: Mon, 04 Aug 2008 13:12:49 -0400
From: Finn Lassen <finn.lassen@verizon.net>
Subject: Re: [FlyRotary] Re: Back in the air
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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If you have a good diffuser ahead of the radiator, ideally the air would 
be all pressure and minimal velocity just before the radiator, and thus 
your relatively slim fan blades should not be a big obstacle to the air.

Al's comments seems to confirm this theory.

Up till now I have always thought it would be a bad thing to put a fan 
in the path ...

Finn

Steve Brooks wrote:
>
> 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 -----
>
> *
> From: Steve Brooks <mailto:cozy4pilot@gmail.com>
> *
>
> **To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net> *
>
> **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*
>
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