Roll coupling #2

[Steven Maxwell]

 Thanks Mike thats what I was looking for much easier to me to move the wing socket up or down in the fuse, and what you said about rudder is also the same a freind found out.
 Excellent Dude.
 You coming to the D4 Championships? Goping to have a pretty good FAI class.
 Steve Maxwell 


----- Original Message ----- 
From: Mike McConville 
To: patternrules at earthlink.net;discussion
Sent: 9/20/2005 9:25:41 AM 
Subject: RE: Roll coupling #2


Yes, Higher the wing, the less dihedral is needed. Roll couple is a function primarily of dihedral. And the dihedral needed is a function of the the distance the wing is from the thrust line. Assuming you have adverse roll couple and need more dihedral, an alternative to changing the dihedral would be to move the wing up. 
Sub-fin, rudder size, shape,hinge-line angle etc play a very small part in coupling but there could be some small effect. Its likely that changes there will also have some effect on pitch couple as well. In my experience, changes there will have a very small effect on roll couple and probably wont effect the change you are looking for if your issue is dihedral related.

There are also a few unorthodox things you can do to effect a change in dihedral such as up swept wing tip shape, ala some Prettner designs, to give the effect of more dihedral,  or fins on the bottom of the wing angled outward to effect less dihedral. 

FWIW.....
m
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Steven Maxwell
Sent: Tuesday, September 20, 2005 9:18 AM
To: discussion
Subject: Roll coupling #2


 I ask this question the other day and got a few replies, all dealing with dihedral, with one exception. Seems that there could be and is much more to this. #1 Could the wing be moved up or down instead of dihedral? 2# Couldn't the rudder size and position,  sub fin added or reduced? Sense the 2 piece wing offers less possiblities of changing dihedral than the old one piece wing.
 Designers?
 Please reply to all and remove the sender.
Thanks 


Steven Maxwell
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