Hi,

I’m putting together an ARF plane and I simply can’t get the throw on the rudder to be equal on both sides. The instructions suggest about an inch and a half on each side. But no matter what I do the closest I can get them is within a half inch of each other. For example one side will go the full inch and a half but the other will only go inch. I have never flown so I don’t know if this is acceptable.

Any advise?


Thanks! (The plane is a ThunderTiger Windstar)

No, that's not acceptable.

Set the rudder trim slide on the transmitter to the middle of its range.

Turn on the transmitter and the receiver.

Look at the servo wheel on the rudder servo. The arm connected to the pushrod should be at a 90 degree angle to the pushrod. If it's not, remove the screw and servo wheel. Rotate the wheel until it can be reinstalled with one of the arms at a 90 degree to the pushrod. Be careful not to force the splines when you reinstall the wheel. The pushrod should be installed in the outermost hole in the arm. Reinstall the wheel and the screw.

Remove the pushrod from the rudder horn. Adjust the length of the pushrod as necessary to get the pushrod to go in the innermost hole on the horn with the rudder centered.

Now the rudder should move the same distance each way. It may not be the full 1 1/2" called for, but it'll be enough for it to fly just fine if it's at least 1 1/8"

If the rudder travel isn't the same both directions, the horn is probably too far back on the rudder. With the rudder centered, the hole in the horn where the pushrod attaches should be even with the hinge line. If it's off more than 1/16", I'd move the horn to the correct position, even if you have to move it up or down a little to put some new holes in the rudder.

Roger

Somewhere in the system you have the pushrods connecting to the servo or the control horn at an angle or the output arm or control horn is not at right angles to the hinge lines.

What you have is differential throw caused by the geometric misalignment of some or all of the parts from above. Correct the angles or compensate for one part with a deliberate offsetting of the other and you'll get what you want.

For example if the pushrod meets the control horn such that the travel axis to control horn line is not a proper right angle then you can compensate for that by offsetting the servo arm and retrimming the pushrod length. If this doesn't make sense it would help greatly if you can provide detailed closeup photos of the control horn and pushrod at the rudder and at the servo. Top down or bottom up to show the angles would be best. From those we could hellp you more.

Thanks guys.

I'll give it a try and let you know how it goes.

-Kevin