INCIDENCE settings

[John Ferrell]

The short, non technical answer:
Incidence is generally considered to be the difference in angle of attack 
between the stab and the wing.

Assume long tailed pattern plane...
I get there by:
Block the tail up to the desired flight angle.
Set the stab to exactly level.
Adjust the wing to 0.25 degrees up relative to the stab.
If test flight trims with other than zero elevator trim, tweak wing 
incidence as required.

The CG will have an effect on this setting, but not as much as you think.

There are people who use 0-0 incidence or even lifting stabs. I will let 
them defend their positions. As far as I am concerned, the function of the 
elevator is to maintain the angle of attack of the wing.
John Ferrell
http://DixieNC.US

----- Original Message ----- 
From: "Pat Hewitt" <phewitt at farmersagent.com>
To: <jonlowe at aol.com>; <discussion at nsrca.org>
Sent: Friday, September 30, 2005 12:53 PM
Subject: INCIDENCE settings


I would like to learn more about incidence settings on our wings. I have a
chance to buy a plane that has preset settings such as O, .25, .50, or .75 
but
how do I make the correct choice. I am sure the best is to have an just able
system but please lets not go there I just want to understand how you pick 
the
correct one.

Thanks

Pat Hewitt
Paola, Ks.






------ Original Message ------
Received: 11:35 AM CDT, 09/30/2005
From: jonlowe at aol.com
To: discussion at nsrca.org
Subject: Backplate Pump for OS 1.60

After seeing the discussion about putting an OS 1.40 pump in the
backplate of an OS 1.60, I got to thinking.  The OS 1.40 pump/backplate
is over $150 from Tower, then you have to get a special 1.60 backplate
for another $100 or so.  In the old days, Perry made special backplates
with integral pumps for .61s.  I had one with a bad pump.  Perry
doesn't make the backplates anymore, but they put in a new pump in my
backplate for less than $50.  As long as we are thinking about making
up special backplates, what about copying the old .61 design for the
1.60, and sending them to Perry to have pumps put in?  This would
certainly clean up the installation of the 1.60, eliminate a couple of
failure points for the separate pump setup, and be a lot cheaper than
using the 1.40 pump.  I have a couple spare old Perry backplates that
could be used as samples for a machinist that I'd be willing to loan
out.  Anyone willing to take this on?

Jon Lowe
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