Perry Mick is using something similar. Note the small size of the
water rad even for the reduced power that Perry's engine is generating.
Note also the use of a NACA duct with a fuel sump in the middle of it.
IMHO it would work much better with a P51 style duct.
The big advantage of this scheme in a pusher is the outlet panel
slopes up so the pressure is naturally and highly negative in this region.

How is it working Perry?

BTW I think your front opening at the big end of the wedge is a bit small.

Paul Lamar

Sorry, I'm way behind on my email, just found this message.
I have about 160 hours on this new rad installation.  Works
great as long as ambient temp is below 70F.  Above 70F
it runs pretty warm in a long climb, close to redline on the
Mazda gauge. Cruise it cools off to mid-range, even with
90F.  I think it is just the limitation of the small size of the
rad. I tried the VGs in front of the NACA, no difference.
I made a bolt-on scoop that doubled the inlet area to the
rad, no difference.

Awhile back I made an exit duct that covered the exit

in front of the fan, but it didn't work, cooling was terrible
so I had to remove it and leave the rad exit open to the breeze
again.

I agree about the size of the inlet.
--
Perry Mick

Thanks for the update Perry. Is this the dimension you are referring to when
you say the "size of the inlet"?

Is this what the "exit duct that covered the exit
side of the rad with an exit hole into the low pressure area
in front of the fan" looked like?

If so I can  now understand why that did not help.
Too close to the back of the rad near the front.

Best to leave it open and pump in a bit more air.

Paul Lamar

Yes those drawings are roughly accurate.

--
Perry Mick
Duckt N7XR
http://www.ductedfan.com

Thanks Perry. This adds to what we are finding out from theory and 
the rad test box. I noticed that about NACA ducts. Adding a larger
external scoop does not seem to help. Once the pressure is built into
the duct no amount of external scoop size seems to help.
One must bleed the boundary layer with a P51 style scoop.

Paul Lamar
 
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