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To: flyrotary@lancaironline.net
Date: Sat, 14 Jul 2007 21:50:23 -0700
Subject: Re: [FlyRotary] FW: Oil cooler air flow
Message-ID: <20070714.215034.3152.18.alwick@juno.com>
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From: al p wick <alwick@juno.com>

Really impressed with your scientific approach Al. I can't remember what
type of plane you have, but for the Cozy, my cooling was dominated by
dead air near rear of plane. That boundary layer gets thick back there.
So I duct taped two pieces of aluminum angle to the air brake and Bam!
All cooling issues disappeared. I do like Ed's suggestions. Sorry not
much help, but couldn't let it go without saying how impressed I was with
your method. Must have been tough to start cutting on your duct. 
You know, I also liked Ernests blower and yarn approach. I wonder if that
would help?

-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 Thu, 12 Jul 2007 21:02:32 -0800 "Al Gietzen" <ALVentures@cox.net>
writes:
> OK, all you aerodynamicists; here’s the scoop – what I did and what 
> I
> measured;
> (Pressures measured in inches of water.)
> 1 – sealed the strake/wing crack in front of exit fairing - - No 
> effect
> 2 – Installed Gurney flap at back edge of exit fairing (see photo 1) 
> – Very
> little effect.
> 3 – Set up manometer to get some pressures. (photo 2)
> 4 – Dynamic pressure in front of scoop, ˝” from surface (photo 3) -- 
> 9.5” at
> 160 mph.  Nothing wrong with that.  Free stream away from surface 
> would be a
> bit over 12”.
> 5 – Static pressure ˝” from face of core – 3 Ľ” (end of tube was 
> pointing
> slightly away from direction of flow at about 60 degrees to the 
> flow; flow
> velocity is pretty low)
> 6 – Static pressure just behind the core --- 0”
> 7 – Static pressure at behind exit fairing, ľ” from surface (photo 
> 4)   – ľ”
> 8 - Installed VGs about 2 1/2 ft in front he exit fairing - No 
> noticeable
> effect.
> 
> So .. . plenty of dynamic pressure in front of scoop and only 3 Ľ” 
> pressure
> in front of the cooler core.  This would suggest that the scoop/duct 
> isn’t
> working.
> 
> Photo 5 is a reasonably accurate x-section of the scoop and duct.  
> Shaping
> was limited because duct entrance is right behind the spar, and by 
> the
> limited thickness of the wing root.  I'm just guessing that the 
> somewhat
> abrupt curvature of the upper wall at the entrance is causing flow
> separation, turbulence; and whatever.
> 
> You'll also note in photo 4 that I had cut the center section of the 
> exit
> fairing to allow exit further forward - that didn't help.  I also 
> did soap
> drops on the surface which way air was going both in front of; on 
> top of;
> and behind the fairing.  In all places the flow was relatively 
> straight
> back.  I'm also guessing that there isn't much chance of developing 
> a
> greater negative pressure at the exit; but, hey, whatever works
> 
> All I need to know is a simple fix:-)
> 
> Al
> 
> 
> 
> 


-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