Aileron to Servo Setup
 

I read an article that when setting up the Aileron servo that the control rod should NOT be 90 degrees to the servo arm when in the neutral position.
I remember the logic seemed sound but I can't remember how to calculate the angle that it should be at.
Does anyone use this theory?
How do you calculate the angle?
Thanks,
KW_Counter

RE: Aileron to Servo Setup
 

I think this link will answer your questions.


http://www.rcuniverse.com/forum/m_17...tm.htm#1705909

RE: Aileron to Servo Setup
 

If you are setting up a flat wing trainer, then many recommend using the two forward arms on a six arm servo arm. You still want them equidistant to the center with the servo centered and the trims center. They will be approximately 60 degrees forward.

What this does, is sets up aileron differential, since the aileron has more authority in the down angle, than the up angle. This differential allows more throw on the upward motion on the opposing ailerons downward motion, since the flat bottom allows the downward moving aileron to be in cleaner airflow, hense more responsive.

You usually cut off the four other arms, one at 90, one at 270 degrees and the others at 0 and 180 degrees.

Hope this isn't too confusing, but all the flat bottom trainer's (including my own) have flown very well with this set up. Even many large aerobatic airplanes profit from aileron differential.

If you are using a computer radio, you can set this up and adjust it. If you are using a standard 4 channel, then the best you can do is what I recommended.

Hope this helps,

Mike Boyd
AMA 7197

RE: Aileron to Servo Setup
 

The purpose of differential in ailerons is to counteract adverse yaw. Flat bottom airfoils are not necessarily the only type to use differential. Adverse yaw occurs because the downward deflected aileron causes more drag than the upward deflected aileron. The effect of adverse yaw is to pull the nose in the opposite direction of the turn. In a real airplane the pilot counteracts adverse yaw with the use of small rudder inputs. In R/C models, we aren't sitting in the cockpit of the airplane, so we can't readily see when the airplane is effected by this condition, so differential may be incorporated. Differential can be used in low wing airplanes also. In this case the servo arms would be set-up directly opposite to what was described by Mike Boyd. Differential can have negative effects in other types of airplanes.

RE: Aileron to Servo Setup
 

Also, trainer airplanes which need differential set-up in their ailerons should generally have this fact well described in their building instructions, I would think.

RE: Aileron to Servo Setup
 

Set it up as described. When your instructor flies the plane, he will immediately know if there is too much differential, or too little, & he will help you make adjustments.

RE: Aileron to Servo Setup
 

Here's what Mike is referring to.

As far as "How do you calculate the angle?" I use the TLAR Principle (That Looks About Right)

RE: Aileron to Servo Setup
 

If set up like MinnFlyer shows, the arms will be about 30 degrees forward of perpendicular as opposed to Mike Boyd's 60 degrees. The 30 degrees is more desirable as if you go much beyond this you will begin to limit the amount of throw available in one direction. In fact, the arm would actually go "over center" unless electronically limited. 45 degrees would be about the absolute limit for a servo that has a 90 degree total swing programed.