Banche

Well I dont know if it is really new or not and I hate that I still dont have a digital camera to give a better description but here it is.



I have a long 4.5 inch SWB servo arm on my HS- 6985HB servo. It is my first time build a gas plane and my first time for a pull pull, airplane is a 30% yak and I got a DA 50. Is this servo enough, its faster than the 5945 and has more torque than the 5645. But its got Karbonite gears?

Normal pull pull setup involves two wires going from the ends of the arm to the rudder. I dont have any directions on how to secure the wires to the rudder using those little metal tubes and such but I think it will be OK.

Here is what I am really getting at----> I am only using one wire. I will attach it to the rudder arm on one side, then I will bring it in the plane and just push the wire through the corresponding hole in the servo arm. then I will take the wire and push it through the oppisite hole that is equally far out on the arm on the other side of the servo, and from there I will put it on the rudder. This makes sure that there is equal tension on both of the wires. It seems like it would work to me. Why hasn't anyone done it? Is there a problem?

pettit

My Feedback: (23)

Your method may work but it runs the risk of slipping through the servo arm holes and changing the center point.

Those "little metal tubes" are called crimps or ferrules. Basically you put one on your wire, loop the wire through the servo arm or the clevis (more on this later) and then loop it back through the ferrule. Pull it tight and then loop it through the ferrule again.

Using a set of diagonal cutters, crimp the ferrule in about 3 places, not tight enough to cut it, but tight enough to keep the wires in place.

The clevis, you ask? You need some way of adjusting the centering and tightness of the system. Put a clevis and a rigging coupler (that's a piece of threaded rod with a hole in one end) at each rudder horn. Then feed the pull-pull wire through this hole and the threaded part can be used to adjust the tension. Be sure to use a nut on the threaded part to keep it from turning.

And use a keeper on the clevis.

MINNFLYER, please feel free to jump in here with one of your great diagrams.

Banche

I would love a diagram but that helps tremendously

AcroJo

My Feedback: (1)

Banche, SWB offers an adjustable pull/pull cable setup with two ball links, two titanium turnbuckles, for 'adjusting' and two composite cable slings for attaching the cable. All you need for the rudder end is two ball links and two rigging couplers as Pettit stated. Off hand, I don't know the specs on the servo you mentioned, but all the 30% I've ever seen have two or three rudder servos ganged together.

I'm doing a 2 metre, 3W Extra Fun presently and on rudder I have one, 186oz./inch metal gear JR digital with a three inch SWB 'offset' servo arm, as I will be crossing the cables. The plane should weigh ten pounds when complete. Good luck, Joe

drumbum

My Feedback: (1)

Not to be off subject. but since you are talking about the SWB horns. i am thinking of getting some for an 87" yak. i was wondering the hole size in the arm for the link? They look rather large. will a DUBRO 4-40 locking clip clevis work in them without slop??

AcroJo

My Feedback: (1)

Lee, on the servo arm I would use nothing but 4/40 ball links. Thats what they are set up for. The hole is actually sized for the bolt that goes through the link. Also check out the pull/pull adjustment rig for the wire. You could get away with clevises on the tail end. Good luck, Joe

65 Chevy

My Feedback: (1)

The Karbonite gears in your servos will likely be a problem. Hitec only recommends the karbonite gears on planes weighing less than 8 pounds. Over the winter there was a large controversy over the karbonite gears stripping and causing the loss of MANY airplanes from 90 size and up to 30%ers. After which Hitec stated publicly in this forum that the hoopla and hype generated by Hitec Sales Dept about the karbonite gears and their strength was supposed to be directed as an improvement to nylon gears and not to be intended to replace common sense and metal gears in larger planes. They went on to say that metal geared servos should always be used on planes over 8 pounds or any plane doing extreme maneuvers. Since I was one of the people who bought into the Hitec Hype and bought the karbonite geared servos for a 25% Edge, you can bet I was a bit upset when I read these threads (Under Hitec Direct Support) I decided to use these servos on a 60 size 3D plane I have instead. I am very glad that I did not put them in my Edge. On the 3D planes third flight, I stripped the rudder servo gears. Now just to keep this in prospective here, the rudder was (is) only 18 sq inches of surface with about a 45 degree surface deflection. JUST IMAGINE WHAT MAY HAPPEN WITH 40 Sq inches or more. If the plane is precious to you, please be careful with the servos and gear-train you choose.

drumbum

My Feedback: (1)

I see,, Thanks JOE