I think you are on the right track using the exhaust as an eductor. You'll use the energy of the exhaust to speed up the air exiting the cowl. Very elegant solution.
-----Original Message-----
From: Bobby J. Hughes <bhughes@qnsi.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Tue, Dec 28, 2010 5:13 pm
Subject: [FlyRotary] Extraction Duct- RV10- input needed
I've been thinking about building an extraction duct (next winter) for my RV10. My exit area is overly large and I'm sure I have excessive cooling drag. The lower fairing ends 5" below and 1" behind the firewall. The extraction duct would join the existing lower fairing. This is an old picture and my muffler is already hanging under the belly. The grid lines in the excel attachment are at 1".
Bobby