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Hi Dennis,
Yes, had 3 grandsons over yesterday myself - so I understand distraction {:>)
Yes, going to more H20 probably helps more than just about anything -well, more air flow also helps. The normally 50/50 has a Cp of around 0.8 where as water of course is 1.0 or a 20% improvement right there. But, then you have to remember to put it back to 50/50 come winter time. Texas gets cold as best I remember.
Several folks have tried cowl flaps with less than overwhelming success. Not certain why they do not seem to used more - they, of course, do add complexity and a small bit of weight. In my opinion, they get to be a real hassle trying to put them in to a nose gear aircraft - not so much in a tail dragger with more room under the lower bottom cowl.
I can tell when OAT changes by more than 2 -3 degrees F just by how my cooling temps are running. So you're on the money about relatively small changes having bigger impact on liquid cooled installations.
I believe that driving a bit more air to your oil cooler will pay dividends.
Best Regards
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda/index.html
----- Original Message ----- From: "Dennis Haverlah" <clouduster@austin.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, June 10, 2007 11:32 PM
Subject: [FlyRotary] Re: RV-7A cooling - continued
Sorry the pictures were not attached - I got distracted - 5 grand kids descended on us for the evening. I'll send the pictures Monday. Your idea for a vertical plate to divert more air from the water and to the oil may be the ticket. Also I'm using about 50% water and antifreeze, I'll change to 10 % antifreeze, 90 % water and a teaspoon to a tablespoon of liquid soap to help lower the water temps more. We have plenty of 95 + degree days here in the summer! Air cooled engines have a big advantage because the cylinders can run 450 deg F and the delta T between the cylinder and fins is much higher. A 10 degree change in max. temp due to ambient temps going up is not nearly as critical for them as compared to us when we are trying to control temps at 200 to 215 deg F. I'm surpassed cowl flaps are not standard issue on rotary A/C. I may have to add them in the future to enhance full power climb cooling.
Dennis H.
UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
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