Closed loop.

[Dove from above]

Trying to use a closed loop system on a funfly rudder.

Two questions please, The supplied horn for the rudder is sort of Y shape. It fits into a slot that needs to be made. It can fit 2 ways,the 2 connections arms facing forward OR rearwards,which is correct. connections near the hinge OR away?

Lastly, the rudder horn is about 15mm between wire connection points,what is the apx servo horn width connection? do I need to match the rudder horn OR adjust to get the right movement when installed?

Very fiddly, I am not going to use this on ele for sure! thought I would give a go at closed loop.

What is the advantage over pushrods?

[Attilio Rausse]

**LINK**

[Geoff S]

The horn should fit facing forwards with the holes for the connections to the cable as near to the hinge line as possible (though I don't think this is as desirable as when using a single operating pushrod).

I use a lot of closed loop connections. There are 3 in each of my DB Moths, for a start and there'll be 3 in my current build, a DB Sopwith Pup. In those cases they are there for scale reasons but closed loop controls are both positive and light, though some might think them a bit fiddly, I like them a lot.

Strictly speaking for the wires to be in constant tension throughout the range of operation both horns on the servo (or slave pivot) and the control surface need to be of equal length (ie form a parallelogram) - just check the geometry. In practice, however, I've never found it to be a problem. On my Moths the servo drives an arm pivotted in the middle of the fuselage with the ends poking outside just in front of the front fuselage as the scale loops do. That means the arm is much longer than the rudder horn yet the system never binds. It doesn't matter if the non-puling wire is slack, the load keeps the rudder where it needs to be. There's obviously a llittle backlash (slack) but I've never found it a problem. The Limbo Dancer fun fly has both rudder and elevator controlled by closed loop connections.

Just connect it up and fly.

Geoff

[J D 8]

The arms should face forward so the connection points line up with the hinge line of the rudder. I try and get the width of connection points for horn and servo arm the same.

Not much advantage for an average model but handy where little room for two push rods or if weight at the rear is critical.

A well set up closed loop will be as slop free as having servo at the tail with short pushrod. For some models like WW1 aircraft an external closed loop will be scale