dbeeler

how can i get more throw on a control surface without servo overtravel or causing the servo to bind? the throws are set at 100% on the radio. i dont think it is a good idea to set it beyond 100%. do i make the adjustment at the servo arm or the control surface arm? or both? in or out on the arm?
thank you for your help

big max 1935

My Feedback: (9)

Go out on the arm & in on the horn .You may need to adjust both to get what you want.Make sure the servos are powerful enough to handle the extra stress. Max H.

Lnewqban

Check this thread for ideas:

http://www.rcuniverse.com/forum/m_81...tm.htm#8150099

Dreddi

My Feedback: (3)

The servos are designed to be over traveled electronically, you cannot over drive a servo by changing the programming in the Tx. By doing it electronically you aren't changing the leverage and thus force requirements of the servo. Which wont be a problem unless your servos are so under rated that a small change in mechanical advantage will stall them. But to change the throws mechanically here is what to do..

At the servo; more control surface deflection = farther out on the horn.

At the control surface; more control surface deflection = closer in on the horn.

jaka

Hi!
Most radios can go to 125% or even 150% trim setting.

Longer servo horn will give more leverage.

Must ask! Why do you want more throw????
You probably know that you can place the CofG further back and doing so you don't need as much throw! And vise versa.
What plane do you have in mind?

jester_s1

It's always better to be running the max servo throw you can before doing the mechanical setup. Sometimes going all the way up in servo throw will cause binding just because of the way the servos are installed, so in those cases you go to the maximum that you can and then do the mechanical setup. IMO, your best setup will be to use the outermost hole on your control surface and then get it right at the servo. The reason being that the more movement in the control rod you have the less any slop in the system will matter. Often though that means that even in the outermost hold at the surface you're controls are too hot, so you'll have to move it in some at the servo. I aim for having 100-125% throw at my high rates once the setup is finalized, and then low rates will be whatever I need them at. That keeps me from losing any noticeable resolution at the low rate and lets me have maximum torque from the servo. Having max torque also improves speed in most setups, since servo speed is dependent on the loading.

So to summarize,

1. Max servo throw in the radio that you can use without binding,
2. Use the outermost hole on the control surface that allows you to get the throw you need,
3. Adjust the throw down at the control arm of the servo.

It's pretty rare on most planes that a pilot can't get enough throw using 100% travel settings and the mechanical setup. What kind of plane are you working on?

dbeeler

thanks for all your input. i want to do this on two planes. a high wing trainer to get more rudder mostly. and on a 40 size super sportster. to get more rudder and aileron. right now, my radio is set to 100% throw (travel adjust) for all surfaces for both planes. also on both planes, high rates are set at 100% for all surfaces. the surface i mainly need more throw is rudder. i have trying to do flat turns and the planes do not want to turn. also with the sportster i am sure i would need more rudder to fly knife edge. so i would like to obtain more throw by adjusting linkage and try the maneuvers again. i just confused myself thinking about which linkage to move (servo arm or control arm) and in which direction. and i don't want to cause the servo to bind. again, thanks for all your input. it helps.

flyinwalenda

My Feedback: (5)

Try to make the adjustment on the control surface horn by moving the clevis in toward the surface as opposed to moving out  all of the way on the servo arm.
When you move the clevis out on the servo arm you loose torque. The rated torque of the servo is measured as far in on the arm as possible and as you move out it gets weaker.

jester_s1

dbeeler, I'm curious how much throw you currently have. Also, how hot do the controls feel at low speeds? The reason I ask is that unless you got really odd with your clevis and horn setup, you should have enough rudder throw to do a flat turn. It doesn't take that much unless you're trying to go straight into a flat spin from level flight. Your issue may be not that you don't have enough mechanical throw, but rather that your rudder servo isn't up to the task. Before a tree ate it, I was able to whip my trainer around pretty quick with the rudder, and I wasn't even close to *****g out the rudder throw mechanically.

Charlie P.

Longer servo arms and shorter control surface horns.