Received-SPF: pass
 receiver=logan.com; client-ip=64.136.30.75; envelope-from=alwick@juno.com
To: flyrotary@lancaironline.net
Date: Mon, 28 May 2007 05:29:11 -0700
Subject: Re: [FlyRotary] James Cowl - RV-7a - Renesis - Cooling
Message-ID: <20070528.052919.3180.0.alwick@juno.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
From: al p wick <alwick@juno.com>

Couple things really grabbed me from the photo's. 
1) Expecting air to turn so sharply going thru the cores. 
2) It looks like fluid flow through the radiator is dramatically reduced.
Am I seeing that right? Hose reduces flow by 70% compared to automobile?
I try not to allow myself to assume it's ok just because someone else did
it. 

I was unable to understand your description of changes. However, if the
facts say that it's a negative change, then go back to what you had. 

I also like the diverter theory, so I'd make up a bunch of different
diverters, then test which makes a difference. I'd make them so I could
easily install and remove them. Recognizing that the "aha" design
approach is seldom real affective. Later I'd make them pretty. 
You don't have to test this on your plane(unsafe). You can test it in
your car. Take a soda straw, stick it out the window at various speeds,
angles. Convert that to facts by placing a clear tube on end of straw.
Fill tube with water. Instant pressure gage. Put a ruler behind it and
suddenly you are dealing with facts. 
Put a diverter on the end of a stick, then test trying to divert air into
straw. You can then easily test different angles, speeds, distance from
straw.

Don't try to finesse your system, throw rocks at it. Big changes. Convert
your ideas to facts. Don't rely on theory and feelings. 

Good luck!


-al wick
Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam
timing. 
Artificial intelligence in cockpit, N9032U 240+ hours from Portland,
Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html


On Sun, 27 May 2007 13:11:09 -0500 Dennis Haverlah
<clouduster@austin.rr.com> writes:
> I had very marginal cooling on my first and second flight - RV 7A, 
> James 
> cowl, Griffin Scirocco aluminum double pass water radiator with a 
> Mazda 
> 1989? RX-7 oil cooler.  Water radiator fin size - 22LX13WX2.5T 
> inches. 
> Oil - 19LX4.5WX 2T  inches.  The radiators are mounted side-by-side 
> 
> under the engine and are at about 25 - 30 degree to the inlet air 
> flow. 
> (The air must turn 60-65 deg to flow through the radiators)   See 
> photos 
> 1 and 2.  After my first 2 flights, I constructed a divider/duct to 
> 
> provide a duct for the engine combustion air to make the sharp turn 
> 90 
> deg. up after the inlet to get to the filter.  The bottom of this 
> duct 
> was also supposed to provide a duct wall for the air going to the 
> radiators.  See photo 3.  Two flights demonstrated this really hurt 
> - 
> not helped  - my cooling.  Now I can barely take off and fly the 
> pattern 
> before getting up to 210 - 215 on oil and water.  The divider duct 
> took 
> out about 8-10 sq. in. of inlet area but removed the engine 
> combustion 
> air requirement form the remaining inlet air going in the larger 
> inlet.
> 
> My inlet is about 50 sq. in. and the outlet is about 67 sq. in.  
> This 
> cowl was used successfully on the Power Sport a/c so I believe the 
> inlet 
> and outlet are at least big enough for 160 + hp.  When I first 
> posted 
> pictures of the radiator installation someone suggested I may need 
> turning vanes to improve flow to the radiators.  I am now ready to 
> try 
> the turning vanes below the radiators.
> 
> Does anyone have info. I can use to design the turning vanes?  The 
> K&W 
> document on page 273 mentions guide vanes but does not go into 
> detail.  
> I am thinking of 2 inch wide vanes long enough to go from the left 
> to 
> right side of the radiators and spaced 4 inches apart  with the top 
> of 
> the vanes about 3/4 inch below the radiator  fins.
> Comments or -- Any other ideas? 
> 
> Dennis H.
> 
> 
> 
> 


-al wick
Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam
timing. 
Artificial intelligence in cockpit, N9032U 240+ hours from Portland,
Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html