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Dihedral effects on CL models

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Chuck_Smith:
I know I'm late to the party here but I'm sitting here waiting for my car to get serviced so what the heck. 

Brett, Howard and others are correct Dihedral is probably the most misunderstood topic on airplanes. It has to do with how roll and yaw are coupled, i.e., Dutch Roll Stability. Since a controline plane is ( hopefully) always in yaw it can be a handy thing to add t a design if the wing is very far off the vertical centerline.

I've been using it for while because a) it allows to lower the wing and give the model a nicer "stance" and b) it's just cool.

The one thing I didn't anticipate was the effect on the control linkages. You have basically two options. One solid joiner between the flaps or a "Y" pushrod and ball links. I guess there is a third option with a round bellcrank but that becomes a weightier and more complicated option.

The simple solid joiner will work, but you can so easily end up with binding it's a bit of a crapshoot. The "Y" off the crank has some really interesting unanticipated consequences, If you're good at vector mechanics and to the cross products you'll see that the inboard and outboard flaps move at different rates. Depending on bellcrank location you can have more or less movement on one side, and it can be more in one direction and less in the other.

This will drive you crazy a first until you learn to embrace it. On my dihedral setups I have more downward flap movement on the inboard flap, they are level at neutral, and then slightly less upward travel on the inboard. The creates a slight rolling moment out of the circle on insides and a very slight inboard moment on outsides. Basically, I replaced my  movable rudder with differential flaps.

It's goofy, but it works, and it makes me smile when I watch them move.

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