Im doing my first rudder pull pull setup and I cant seem to get rid of the slack in the opposite wire when I deflect the rudder. I have both of my clevis's on the outer most hole of the control horns. The wire slacks so much that it drops a little. I was trying to find some info before posting this, but Im still unsure on what to do.

are the wires crossed? the wires should only be tight enough so that you can't move the rudder without moving the servo arm...ahhh Ackerman, is what you have discovered

Having the opposite wire go slack is normal, depending on how you ran the wires. Concerning Ackerman, here is a link to a site that explains it:

http://members.cox.net/bdfelice/Pull-pull/pull-pull.htm

On my Katana, I crossed the wires and added Ackerman to the setup. Also, you should try to match the length of the servo arm to the length of the control horns or one piece rod, at the surface. Click on the link "Ackerman" within the page in the link above to see some diagrams.

Jesse

If the wires are tight when the rudder is at neutral, it is OK if they go slack when deflected.

here is a couple of examples of a pull/pull for a tail wheel but the basic idea applies to a rudder as well .

first is the attachment at the servo using small quick connects for my FW190A8 which is currently under const. here's the build thread http://www.rcuniverse.com/forum/m_56...tm.htm#5620546

second is my P-47, the attachment point for the P/P,and rudder push rod,and the tail wheel.
for the P-47 I used ball links with soldered threaded ends, to the 30lb test steel rubber coated fishing leader,I crossed the wires through some extra golden rod, on this plane I also put EZ connectors at the tail wheel so I could take up the slack of the wires this was my first attempt at a pull pull set up, it works great,and is smooth, but tightening the wires is time consuming since acess is limited through the fuse, for the tail wheel, for a rudder obviously alot easyer .

the set up on the FW190 is much more strait forward, again the cables are crossed in the fuse, running through some plastic tubing,whats different is I used cable crimps,I got from the bait and tackle store, at the tail wheel, there stronger than you can believe, and then small EZ connectors at the servo.
I pull the wire tight through the EZ connectors and tighten the allen screw down there is no slack what so ever when turning the servo either direction I am planning on a push rod for the rudder on this particular build.

but for any other P/P application these methods work well,I have found that crossing the wires help with keeping the slack on the wires to a minimum.

About three months ago Dick Pettit did a great right up on setting up a pull/pull system in RC Report magazine. I now do things his way and that slack doesn't happen. Sometimes you just can't set up a plane and be able to get rid of the slack but I have never had any problems because of it. It's easy to do the set up correctly in a kit or scratch build but in an ARF you are pretty much stuck with the way things are.

Gray Beard, how does he do it?

I do mine mine the simple way. Measure how far apart the holes in the rudder horns are going to be. Last plane I did they were 1-3/8". Then use a servo horn so the wires attach 1-3/8" apart. Like someone else said the slack wont hurt but if it bothers you try it my way.

David

Call 256-722-5279 and ask Heather for the back issue that has it in there, while you are talking to her subscribe, sure beats the heck out of the other RC advertisement magazines. They do have a website but other then the photos of the models I don't know what else is in there? www.rcreport.ws go take a look, they may have it there?

Never mind, the web site wouldn't let me in??? Make the call!!