I am going to be building a hybrid fun-fly type plane (the Wacky Bee III from HSRCM http://www.hsrcm.com/) in the next couple of weeks. Right now I am getting all of the materials together and I am debating if I should install Pull-Pull controls or go with pushrods.

If you look at the plans you will see that the servos are mounted in the aft portion of the fuse, making the distance from servo to control horn fairly short. The designer recommends a pull-pull setup.

I did a search and read a lot of posts about pull-pull setups on this board, but I am still undecided on what to do. I have never installed a pull-pull setup and I am just wondering what everyones opinion on them is. Are they worth the time and effort? Or, for a model like this one with such short distances between servo and horn, would it make more sense to just go with a nice stiff pushrod?

Any thoughts on this subject are appreciated.

well you can't run pull pull when the servos are in the tail,you would have to mount them in the fuse up front to have room to run the cables.it is a very posative system when done right

Why do the servos need to be up front? There is approx. 8" between the servo pivot and the hinge line, that should be enough room for a cleivs and threaded coupler on each and 4 to 5 inches of cable.

If you look closely at the photos of the "Bee" on the website you will see that both the elevator and rudder use pull-pull. It is not uncommon for tail mounted servos to use the lighter pull-pull method to connect the servos to the control surfaces. I would follow the plans and use whatever is shown there.

GalenB:

Do you think it is worth the extra time to use the pull-pull on an airplane like this? Oe do you think that either pull-pull or pushrods would give the same performance?

The link didnt work for me, so I cant see the exact plane.

However, I have a 3D plane that has a pull pull setup on the rudder. The servo is mounted directly under the fuselage in the tail about 6 inches or so from the rudder. It works well for me.

Pull-pull systems aren't that hard to setup, and yes I think it's worth it on this plane, especially since it's designed for pull-pull. If you set it up and don't like it, just replace it with a pushrod.

Thanks -- this is exactly the response I was going to give...

the designer says pull pull and there must be a reason i would stay with the plans