Re: an aircraft design question


Why change the original design? It would have probably flown very well on three channels.
Ailerons on a wing with significant dihedral and lots of drag will often cause a lot of adverse yaw. Removing the dihedral will cure SOME of that. However, barn door ailerons cause more adverse yaw than strip ailerons, so you're back to square one there.
Less dihedral, differential throw and/or aileron/opposite rudder coupling may help.
My advice would be to build a new, stock wing, and fly it with three channels. Dr.1 Driver "There's a Hun in the sun!"
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Dr1Driver wrote:

Got it backwards. You want your rudder to turn the same way as the ailerons, because the problem is adverse yaw, causing the plane to turn against the ailerons. Other than this detail, I wholeheartedly agree. Differential throw is also a great idea.

Absolutely. When you add ailerons to a plane designed for three channel flying you are opening a can of worms. You soon discover that you have to change several things in order to make it fly right, and you end up building a whole new set of wings. Just leave it like it is and have some fun.
By the way, when you think that you are finished with this plane because it has nothing more to offer, try some new maneuvers. You will probably discover that it has another entire performance envelope that you didn't know about. I used to teach new RC fliers on a plane that I designed for 049 and two channels. We would build the plane together (a 42" span all sheet flat bottom trainer that looked a lot like a Goldberg Eaglet, but smaller and a lot lighter), then fly it without a buddy cord. It was a very stable, lightweight, durable and friendly airplane. One friend of mine had such a successful time learning to fly it that within a few lessons he was just buzzing it around at constant altitude and looking great, and he proclaimed that he was ready for something new. So I took the radio from him and did a split S, rolls, a snap roll, a powered spin, an immelman, and a quick succession of tiny loops. He was so impressed that he ended up flying this plane exclusively for the next several months, and he didn't care about ailerons any more.
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DUH! You're absolutely right. My apologies. It was late when I posted that. Dr.1 Driver "There's a Hun in the sun!"
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Differential will help. You could use two small servos in the wings, and a computer radio to do the differential (good excuse if you don't have one), or change out your 90 degree bellcranks for 60 degree (pre-computer solution). If you have already installed 90 degree bellcranks, can't get at them, and have a single rod to each aileron connected together at the wing-center aileron servo, then you could still effect differential with a funky linkage that connects each of the wing pushrods to the output wheel of the servo at a different location (say 30 degrees apart from each other) such that the "up" aileron movement is increased, and the "down" reduced. The hard part about this would be if your horns are on the bottom of the wing (as they probably are on a parasol), since the control rods need to crossover; but it could be done.
If building a new wing, think about using a semi-symmetrical airfoil, and reduce or eliminate the dihedral. Frise ailerons help with adverse yaw too (where the leading edge of the "up" aileron hangs into the airflow below the wing to increase it's drag).
The other posts about keeping it simple have a point. Maybe this isn't the airplane for what you want to do. OTOH, it's a hobby -- knock yerself out.
--
Charles Wahl
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