I have a question regarding Bellcrank setup. Both my pattern planes have a single rudder servo running into a bellcrank that then has the pull-pull cables running to the rudder. Can someone tell me the advantage of this over just running the cables direct from the servo to the rudder. thanks.

A bellcrank takes the tension load from the cables off of the servo output shaft, it can give some more options for setting up throw.

I've never tried the bellcrank system, but then again, I've not been flying 2m ships.

The bellrank systems are definetely more versatile tho.

What you gain in a reduced load on the servo output arm you lose in having a more complex linkage with the associated increase in play.

In my opinion, with a decent ballraced servo if your cables are so tight that you damage the servo then they are too tight. With them properly set up you can link straight onto the servo with no problems. Less complexity therefore more reliability and less slop.

James

You've received a variety of 'views'-----I will add one more. I use the bellcrank method (my design but they are all similar) and that is the only way I would go.

As to this being more complicated-----I really don't think so. After you get done with servo bracing on the direct setup I think this is simpler and very reliable, not to mention the ease of throw adjustment. (Servo bracing is required to keep the isolation grommets working otherwise you've got rubber mounting right where you do not want it.)

You can do a simple comparison. Set up a breadboard example each way. Then make your choice. I'll be surprised if you choose the direct servo method.