I have been wondering about this every since I saw it. I would like too know if anyone can tell me - whats the pros and cons of the following. This is just out of curiosity sake.

I hate it when I don't know something - it eats me alive!!![:@]

1. On most planes, which I have seen, the two elevator halves gets connected via a "rod" - which you glue onto/into the one and also the other. This then holds it together (and it becomes one) and only one of the elevator halves has a horn mounted to it, which then is connected to the servo with a pushrod. The servo moves and the both elevator halves moves - plain and simple.

2. The other I have now seen in a plane is where the two elevator halves are NOT connected too each other and both has a horn mounted onto them. You then have two pushrods going up into the plane and then is joined too one single which then gets mounted too the servo.

Now I would like too know - is option 2 better or doesn't it really matter. Why do people/manufacturers have these two ways in doing it? Is the one better than the other?

I think here in the Beginner forum is another thread which they are discussing the technique used in option 2.

Like I said - this is purely out of curiosity and something I don't understand.

The first method uses a torque rod that connects the two halves together. See my drawing which I will post shortly (after I draw it).

The second method uses a pair of pushrods that are joined together near the servo in the servo tray under the wing. Depending on how you do that, you would use either a pair of metal pushrods that are either joined together with silver solder or using wheel collars and a set screw... you push the ends of both rods together with one longer than the other, then slide the collar over both and tighten it down.

There is also the method that uses a pair of servos in the rear of the fuselage, one on the right and one on the left, each has it's own pushrod connecting to it's horn on the elevator.

The first method is used on smaller aircraft, trainers, and so on, that don't have as much stress back at the elevator when maneuvering. And, you cannot adjust them separately unless you bend the torque rod, difficult when all is installed.

With two pushrods, you can adjust each half individually for straight tracking of the aircraft. And, of course, the same follows with two servos, one on each elevator half.

I have all three. I have a club trainer that has the torque rod, three other aircraft, one sport and two pattern types with pushrods joined in the third method in the drawing, and another aircraft with a pair of servos back aft. I'm sure some others will have more pros and cons of each method, but if your plane comes with torque rods, you can do either the torque rod method or leave it off and control each half separately. It just takes the additional control rod from the servo and some additional work to get it installed.

CGr.

Okay so basically with two pushrods you can do better adjusting (if that is the word too describe it) and it also lessens the stress on equipment when doing maneuvers?

My Edge has the "Torque Rod" method and that was what I have seen on most of the planes I've had a decent look at.

Then when I saw this method (refer too teribble drawing) I started too wonder about what difference it would make.

Would the "Torque Rod" method be sufficient for a Edge 540 .60?

Well, if it comes with the torque rod, then I would have to assume that it's been tested with that method. I just feel that it puts a lot of stress on the one single control horn during maneuvers.

The problem with the long control rods when using the split method is that they can bend and flex if not secured properly inside of tubes. The Sullivan Goldenrod or their carbon rod comes with tubes that the rods pass freely through but the rods have to be secured either on or in the formers along the inside of the fuselage. If your plane is an ARF, then you will have to get inside to secure those rod tubes somehow.

What I did was I carefully removed the bottom covering to gain access to the inside of the fuselage. Then I drilled out holes in the formers where the two tubes would go (one on each side because you join the rods close to the servo in the wing saddle) making sure that you have the tubes going as straight as possible, one on each side, as I said, leading to the hole in the fuselage where the rods would exit to the elevator. You can also do this for putting a tube in for the rudder, by the way. Then you lay the tube along side of the formers where the holes are, mark them with a permanant marker, remove it, scruff the tubes up where the marks are (this allows epoxy to set up and bond with the tubes) then slide the tubes in the holes all the way back to the rear of the fuselage. Apply a bit of epoxy at each of the holes in the formers (returns the strength and holds the tubes in place) and let the epoxy set up.

Once set up, make your rods as I showed in my drawing or as you wish, your choice, the pass the rods through the tubes.

Now on the rear of the fuselage, where the rods exit, what I do is measure the threaded steel rod so that it is long enough to pass into the center of the Sullivan rod far enough into the rod so that the steel rod would be well inside of the fuselage. Another drawing will show what I mean. You want strength so that the rod does not flex outside of the fuselage between the tube and the horn. You want that stiff.

At the servo end, do that measurement also so that the threaded rod is far enough inside of the carbon rod (or golden rod) so that it goes to where the string is at the joint of the rods.

I'll up load a picture of what I mean shortly.

CGr.

Hey CGwith all these nice drawings, MinnFlyer will be hiring you. Not a good breakfast today, included hash browns, english muffin, bacon and poached egg. Chock full of nuts coffee of course.

All three work well....Like CGretired I have all 3 as well...the only real draw back to the 1 horn with a connecting rod is the connecting rod can loosen and cause slop...an advantage 2 the other 2 methods is if you break a control horn you might have a chance to save the plane with the other elevator half, and of course the same with 2 servos and 2 channels if a servo goes bad....I've only had 1 servo fail in flight..so the bottom line is they all work well...
Good luck

One minor point here. I posted a procedure that I use to secure the steel rod inside of the Sullivan rod using an electric drill and some CA. Works fast and is very secure.. but you have to do the joining carefully but very quickly and all at once because if you stop the drill rotation to soon, the rod will sieze and you won't get it out. So, a little forethought and planning before you actually do the joining works wonders. I forgot to mention in the other post that I hold the Sullivan rod with a pair of pliers so that it does not turn while you are trying to push the steel rod in. You might want to practice on a piece of scrap Sullivan before you actually to the bonding so you will see what I mean. The CA acts like a lubricant at first, but will set up very quickly due to heat created by friction.. but as long as you keep it moving and move fast, it won't set up immediately.. but if you stop...

CGr.

Hi Irish.

Corn Flakes, 1% milk, decaf Starbucks, and a banana.

EKG went well yeserday for my annual. Next is a stress test and echo cardiogram in May. Both are bi-annual checks.

CGr.

Okay I understand now. Thanx guys. I think I should take the advice/opinion and perhaps use the method that CGR gave there. It really seems too be much safer than the one I have now - if something should go wrong.

I learn new things everyday on these forums

Banana, I ate one, once. Congrats on the test. I don' like the stress test. Going flying this morning. Temp is about 40* 3mph wind. Hopefully I can burn a gallon.

Irish.. you can burn a gallon one of two ways.. in the engine, or to make a fire to keep warm..

Korps.. added a drawing to clarify fuselage junction.

CGr.

If I bang it in I will probably use your option 2

Korps.. Wellington, SA.. way down there!! Just looked it up on Google Earth.

CGr.

C G: When using 2 pushrods and 2 servos to control 2 elevator halves I prefer to cross the rods inside fuse. Seems to come out fuse more directly in line with control horn for me. Just another one of those personal prefferenses.

Yeah, Ted. I understand. But, the planes are ARF's and the tubes were already there... except the Excellerion which is pull-pull everything (elevator and rudder).. a lot of kevlar line going back there.

The only real problem with the cross method would be securing the tubes to formers for planes that don't have the tubes already. The Tiger 60 that I put together way back when was like that. I had to remove the bottom covering to gain access to the insiide to put the Sullivans in.

CGr