The wheels work real well providing you allow for the hinge pivot line offset at the rudder post. Otherwise you've gained nothing. Best setup is a wheel at either end. Problem here is you have to build the wheel into the rudder post at inception.

My new Carden Extra 330S has BIG wheels at either end, coupled like a tiller bar setup. Works great...

I have a web address somewhere for a very good detailed article on this. As soon as I find it I'll pass it along.

Paul,
The wheel doesn't correct for geometry. In fact the rudder should not have any ofset from the hinge line as mgalvin had alluded to.

However with a servo arm you must make sure that the arm cable connection points are perfectly paralell to the horn connection points. This is usually done by making identical length cables and placing the servo on the centerline of the fuse. When you get it all connected and the rudder isn't quite on the center you usually start adjusting the cable lengths. With a wheel you just trim the servo with you radio. The same thing with cable tension. With a wheel you adjust one side, and with a servo horn you really should adjust both sides. A wheel is just easier.

You probably could use a standard servo wheel if you could mill out a slot all the way around and fabricate a cable hold down point. Of course the wheel would be a little small.

http://members.cox.net/bdfelice/

Check out his fun fly designs as well - some of the lightest construction methods I've seen for glow powered.

Ok...now i understand why one line goes slack at or near full deflection (Rudder) !!


I have 2 questions......


1.....what harm will this cause ??

2......how do i get a servo arm that matches the offset of the rudder hinge line ?

Daryl

That's the web site I was looking for, thank you...

Outsider

The slack cable is not so much a problem as the harmonics it might create... And the slack has to be pulled tight when opposite rudder command is commanded... This creates undesirable hard to duplicate; consisten, rudder command. It certainly not very smooth with slack as well.

Best method is to obtain a tiller-bar/bellcrank. Measure the offset and install the rudderpost thereafter...

Here is the link for the Ackerman system, which is the way I have mine installed and it is perfect,

http://users.ids.net/~bdfelice/ackerman.html

Regards
Roger
ACM Rep....

Team ACM
Fiber Optic Servo Extensions
Forgues Propellers
Multiplex Dealer
http://www.aerografixs.com
Model-Scan Frequency Analyzer

If you want to see some neat pull-pull systems including the Noll- Boston System,go to the Carden Aircraft site.Click on links & go to the Sure-Link Custom Control System site.Saw these at Toledo.Good stuff.