Mailing List flyrotary@lancaironline.net Message #8513
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: engine mount geometry
Date: Sun, 23 May 2004 09:36:30 -0500
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
mike McGee and I were just talking about my setup, I.e. going from a left turning mount to a right.  he pointed out that this is exactly what Tracy just did with his -4.  we guessed that he didn't change the engine mount geometry, but perhaps offset the vert stab instead.   
 
Actually, Tracy has no offset in his RV-4 mount, or his vert stab.  He originally had a small wedge type trim tab on his rudder which worked fine until he changed drives.  Now he's moved that wedge to the other side of the rudder, and it isn't quite big enough for the new drive and prop.  No surprise there I guess.   Now, I believe he's in the same boat we are for his RV-8 mount, as I think it has left offset built in. 
 
 I would like to hear what you guys say about this geometry.  does the vert stab offset create drag?  is one way better than another?  will higher cruise speeds affect the alignment, I know it affects rudder trim?
Kevin Lane  Portland, OR 
 
I'd like to know this as well.  As far as I can tell, offsetting the vert stab is no different than applying some rudder trim, which I can certainly do.  The real question for me is whether the engine offset is any better than rudder trim, in terms of drag at cruise speed.  
 
Cheers,
Rusty (making the TB flange, and fitting the tubes later this afternoon)   
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