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The RV10 rotary cowl was built with the offset that was
designed into the CCI mount. I will try Saturday to calculate what Fred built
in. The cowl is adjustable in length (straight section by firewall) between
48.75 and 52.75 inches from firewall to back of the spinner. It will
take some sanding to get it centered.
Bobby
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 :)
Jerry
My 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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