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Old 03-29-2006, 03:58 PM
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Ed_Moorman
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Default RE: Ultra Stick 60 rudder design question

Ernie,

High wing location, sweep back and dihedral cause roll in the direction of the rudder

Low wing location, sweep forward and anhedral cause roll opposite to the rudder.

On a high wing plane, you will always need anhedral or forward sweep to counter the pro-direction roll. Conversely, if you build a low wing plane with a flat wing, it will roll opposite to the rudder. I have shown this to several people who thought they were helping by building a low wing plane with a flat wing. Pattern planes with a flat wing will use a swept leading edge to counter the roll.

As for pitch, this is harder, a high wing low tail will pitch toward the top. Sticks need a higher tail-their's is usually on the bottom.

Low wing and high tail will pitch down (toward gear). A Kaos will usually need a lower tail.

I don't know if you have flown either of the UCD's, 60 or 46, but the 60 size has a lot of roll and, with its high tail, right on top of the fuselage, the plane pitches down pretty badly with rudder. The UCD 46 has the stab at mid fuselage, which I think was an attempt to corrrect this.

It's all a compromise and since mixing was invented, there has been less experimentation with solving the problem. The experts in pattern usually mix everything out.