hi - i'm going to install a pull pull elevator system in my cg super chipmunk - i fully understand the rudder pull pull set up but i'm not clear on the elevator set up ? do i install the servo on its side ? do i install the servo as normal and cross the wires ? use a vertical horn/cam system if yes how do i install it or is there another method - thanks in advance

The easiest thing to do is to just mount the servo on its side - preferably in line with the stab

Hi!
Much easier to just mount the servo as usual in the fuselage and have the wires crossing!

thanks for the rapid response - i'm guessing the rudder and elevator servo's will be fighting for centre axis ? do i install one off centre or do some stacking thing?

You can, but there is really not enough pressure on any of them to cause any fraying or binding problems

Please BE CAREFUL with pull pull cable ends, especially with elevators.

When using regular stock rod/clevises, be careful as GAS engine vibration levels weakens those cable ends. I almost lost one!
It is just my opinion..

I use pull-pull on all my large planes and the only care you have to take is to make sure you have a bit of positive Ackerman built in. The servos can be placed just about anywhere and in any position if you use some cable guides. The inner (even the outer works) tube on nyrods work well as guides. You can also have different distances at each end; i.e. the control horns can be longer or shorter than the servo arms as long as things do not bind up at maximum throws. Do not overtighten the lines, you want them barely taunt at neutral and the line not being pulled will become slightly slack (if you have the Ackerman setup) when the surface is deflected. I know that some will disagree with what I've said here but I use this system all the time and in some 20 years and as many models, have never had anything but success with these setups.

many thanks for all your replies

Rodney,

Time for a little learning for those of us who don't know. Just what is the "Ackerman setup"?

Hi!
http://www.qmfc.org/school/ackerman.htm

jaka's reference says it all, very good information and illustrations.