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Old 10-19-2006, 10:23 PM   #8 (permalink)
Baron
Gettin' Lower!
 
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Join Date: Jan 2006
Location: Florida
Posts: 71
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Default Re: Lets talk some aero...stab location

Aside from those mentioned already (wing & stab vertical placement, dihedral), coupling also depends upon cross-sectional shape of the fuselage, fin & rudder geometries, rudder/elevator proximity, vertical and longitudinal CG location, etc.

Then if you could (remarkably) balance all these effects throught the range of sideslip angles while maintaining a CG suitable for the type of flying desired, you still have asymmetric prop forces that cause both pitch and yaw moments due to sideslip

However, generally speaking for most aerobatic aircraft - holding all other variables constant - a lower wing results in adverse roll (opposite direction of rudder application), higher wing results in proverse roll (same direction of rudder application), lower stab results in positive pitch (nose-up), and higher stab results in negative pitch (nose-down).

George Hicks wrote a very interesting piece on his research and thoughts regarding coupling, I think it's on RCU. It's a .txt file attached to a post in the aerodynamics section... very highly recommended reading on a very complex subject matter.

-Baron
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