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Aileron Guidance needed

I'm building a normal size FT design Pietenpol with flaperons. Need a bit of advice regarding what size to cut them.
I'll be using 5g emax servos and using a separate ubec as I don't trust the 20a emax esc's ability to power 4 digital servos. Be running a 2204 emax motor and 6045 bull nose props.
Also would it be wiser to keep the dihedral in the wing or just use a straight wing?
All advice appreciated. Photos of progress so far to follow. Happy building and flying everyone.


Well-known member
With full length ailerons, the standard recommendation is 1/8 of the wing cord. To avoid adverse yaw, make sure the up aileron goes up as much or more than the down aileron goes down.
To dihedral or not is a matter of personal choice. Dihedral will give more stability. My self I like a bit of instability.
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Active member
Dihederal negates some aileron authority, fixed by using less down (differential) aileron, flat wings are preferred, but flat wings only yaw on rudder command. Flat wings tend to be stronger in the center joint.
So I'll stick with the flat wing then. Thanks for that. Need to measure the wing chord now. Thanks for the help. I modified the landing gear fairings too as per the modified bushwacker article. Feel doubling up and putting in bevels helps with strength and seating against the fuselage. Landing gear should be rock solid with the mods and 65mm thin wheels. This is the progress pic I promised. Just waiting on servos and an esc coming then see how this bird flies 4ch.


So got the modified landing gear fairings on. Rather pleased with them. They strengthened it up massively and looks well with the wheels.
Wing I think may need redone. Done 1/8 of the chord for ailerons Depth. Worked out like 20mm and seems way too small, though proof will be in the pudding(maiden flight crash😂). Next time I'll increase this to 1/4.
Finally I got the power pod and faux engine installed. Made some 'reinforcement discs' for the BBQ skewers out of guitar picks, placed internally on power pod and power pod bay.
I'll post a pic or 2 of progress tomorrow. For now I'm off to bed. Happy flying everybody.


Well-known member
Worked out like 20mm and seems way too small, though proof will be in the pudding(maiden flight crash😂)
Youll be surprised how much control small ailerons have if they are on a large wing. When i built my Hurricane, I thought the ailerons were on the small side and dialed up the rates, the first launch I attempted a small correction and rolled it upside down.


Well-known member
Keep in mind aileron authority is dependent on several factors: control surface size, surface deflection, and relative airflow. A small control surface that has very little throw is all you need on a fast moving flying wing, for example. That same control surface and deflection setup would not be effective on a larger wing that's flying slowly.
Little update. Servos and esc's finally arrived in the post yesterday. Spent a while this morning soldering up esc's(one needs redone on the esc side as I put the wrong bullet connectors on).
Got the servos and control horns installed. Planning on running the wires through the cavity at the front of the spar and down the back of the front canines to keep everything clean and tidy. Will have another update later hopefully with the model basically complete and just in need of an appropriate battery and receiver.
Happy flying and (re)building everyone😁. Not long until the maiden flight (crash test, ahem) of this bird.


Now she's altogether. 253g without battery and receiver. Just waiting on them coming as well as a ubec. I'd say ready to fly weight will be about 350g-ish. Beats 489g from my first attempt that flew like a pig.
Next post will be performance and/or damage report😋. After all the addition of ailerons is experimental so this could go very wrong. Can't wait to find out.
Could anyone give me pointers on flaperon mixes and set ups by chance? Havn't got my head around them yet. Thank you and happy flying.



Well-known member
Your Tx should have a flaperon setting, use it. If you can, follow the direction in your Tx manual. The set by set instructions will depend on your Tx and on how you installed your servos, if they are facing the same way or the opposite way. Let us know your Tx brand & servo orientation, if you need more help.
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Using Flysky Fs-i6x Tx. Doesn't have a flaperon option but managed to find a video online to help set up some 3 position mixes. Think the video was from RCwithAdam on YouTube.
Everything with this bird is ready apart from receiver, throws and rates check, glue on wing and then maiden. Hopefully next week get testing this one out and have another update for then.
Happy flying and building.