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-   -   Ball links for Rudder horh? (https://www.rcuniverse.com/forum/questions-answers-154/7947963-ball-links-rudder-horh.html)

sportflyer-RCU 09-12-2008 06:22 PM

Ball links for Rudder horh?
 
The servo arm and rudder horn configuration in the GP Sukhoi SU31 is such that the best config is a ball link at both ends. I am hesitant to attach a ball link at the rudder horn because its one of the Large Dubro heavy duty horn designed for 4-40 clevises. I would not like to apply side forces to the rudder horn and also the material thickness around the hole seem too this for this. Any ideas besides using the clevises but making sure its one of those with a metal lock. Tks

Gringo Flyer 09-12-2008 07:43 PM

RE: Ball links for Rudder horh?
 
Your right, the ball link is not a good idea at the rudder end.

I am not sure how you are going to go without a clevis. The only other attachment method I can think of is a z bend, but I wouldnt use a zbend on the rudder end either.

Why not use a high quality 4 40 clevis. I like the metal gp ones but I think any would be fine.

sportflyer-RCU 09-12-2008 08:00 PM

RE: Ball links for Rudder horh?
 
I will use Sullivan heavy duty clevises with metal locks.

woodbutcher 09-14-2008 07:01 AM

RE: Ball links for Rudder horh?
 
What about swivel ball links ? You get the action but are totally secure with a bolt. I've used them at the elevator horn with no problem.

http://www3.towerhobbies.com/cgi-bin...?&I=LXD610&P=7

daveopam 09-14-2008 11:41 AM

RE: Ball links for Rudder horh?
 
Those ball links are nice but should not be put on the control surface horn. Under a load they will twist the horn. A clevis puts a straight load on the horn without the twist.

David

sportflyer-RCU 09-14-2008 04:33 PM

RE: Ball links for Rudder horh?
 
I tend to agree . They should not be used on control surface horns due to twist action under load .

JohnW 09-15-2008 10:52 AM

RE: Ball links for Rudder horh?
 
Bah... the ball links can be used on horns. I'm using dubro 4-40 ball links on the control horns on my turbine. Yes, this puts side load on the horns, but they hold up just fine at 200MPH. Granted, not ideal, but it does work as long as the horn is strong enough to take the side load, and these are (carbon fiber.) I'd agree in that I wouldn't use his method if the horn is weak and bendy, but then again, I wouldn’t use any weak and bendy control surface linkage component in the first place.

daveopam 09-15-2008 06:34 PM

RE: Ball links for Rudder horh?
 
How many guys know the difference John? I have seen this done alot and it's a bad idea. Most control horns are plastic not carbon fiber. They will twist under a load. If the horn is going to twist why bother with a ball link setup? In most cases the ball link on the servo end and a metal clevis on the horn is a better setup. At least IMHO

David

sportflyer-RCU 09-15-2008 08:47 PM

RE: Ball links for Rudder horh?
 
Does anyone make heavy duty large control horns with the ball link integrated besides Robart ?

JohnW 09-15-2008 11:24 PM

RE: Ball links for Rudder horh?
 
Dave, point taken.

Sport, I know of other systems that do something similar, but not with a ball per se. MK products makes ball bearing linkages that center the load on the horn and dubro and others have linkage setups that center the load. These systems are designed for large planes. All of these products will use a machine screw as the control horn which must be securly mounted in a block that is then inset and glued into the control surface.

Another method I've used before is to install two control horns side by side. Put the ball in between and run a bolt thru the whole mess. No side load that way.

daveopam 09-16-2008 09:23 AM

RE: Ball links for Rudder horh?
 
That's sounds like a good idea John. Putting two horns side by side. That's why I enjoy RCU so much. I guy can learn something everyday.

David


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