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| It has certainly been done that way by many. The only problem I can see is that it kicks the nose over and may not fit in the center of the cowl opening. Of course, if you are building the cowl, you can make it look good. Jerry
My kit suggest to install washers between my mount and the firewall to get the thrust I need. This doesnt sound like a very good way to do it to me. Is this really the norm for adjusting thrust? Bob Mears Supermarine Spitfire
-----Original Message-----
From: jerryhey@earthlink.net
To: flyrotary@lancaironline.net
Sent: Wed, 11 Apr 2007 3:22 PM
Subject: [FlyRotary] Re: Mount offset
Bobby, I am sure we can get it right. I am interested in Blake's suggestion because I can do the drilling of the S-beam on the mill where I have more control. We can also do something like you have just suggested by measuring from a point on the S beam back to the firewall. And then instead of moving the motor around, I can just move the firewall. Same thing in reverse. Jerry
On Apr 11, 2007, at 5:05 PM, Bobby J. Hughes wrote: Your correct Ernest. I should have specified an RV. I think all of the
RV's are designed the same. I have read somewhere it is 1.25 degrees.
Just trying to confirm.
Bobby
The direction of the engine offset, and any fin offset would also depend on the direction of propeller rotation. The fin and engine offset must agree. Lynn E. Hanover
Also, you might ask your engine mount builder if he can truly resolve a quarter of a degree. I am sure he is pondering this issue and wondering the same :) JerryMy simple (hanger engineering) approach would be to draw a straight line the length of the left side tubes. This should be a known length. Then using a protractor draw another line the same length at a 1.25 degree offset. Measure the difference at the end of the lines. Then draw a line 47.5 inches (firewall to C-drive face) and repeat with a 1.25 degree offset. Measure the difference and subtract first set of measurements. That should provide a good estimate for how much shorter to make the right side tubes. Washers could be use for fine tuning if needed. The flying RV10's seem to be as much as 1/2 ball out to the right in cruse. Not sure how much it would be without the offset. It does vary with airspeed. Some are installing rudder trim. Van's mounts have the offset build in. Tracy also has offset built into his RV8 mount. I think it is needed to make the plane fly correctly. Bobby
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