Hi

I´m building a G-trick and want to try the Mk dual elevator coupler, is this something you recommend on this plane or does anyone have a better idea for the elevator coupling?

Thanks,
Tobias Jonsson, Sweden

It's a good idea. Rather than the standard y-rod system, I have used the MK device on all of my ARFs.

Mark

I second what Mark said.
Go for it!!.
I use one on my Pilot BeatOn 90. The plane was ARC, so I had much less trouble installing the support for the bellcrank.
Just be careful when making the holes for the mounting plates that comes with the bellcrank. They are thin ply and should be installed inside the fuse.

I also recommend ball bearing linkages on all the connections points to make the elevator most precise. I tried ball links on bellcrank output arms, but no good.
Use carbon fiber pushrod from servo to bellcrank, bellcrank to elevators.

Good luck.

What kinda of problems did you experience with ball links?

Toymaker,
The ball links were a little bit too tight. It is also not a good idea to sand the ball, and there is no way to make them smooth like the ball-bearing. With many flights, they wear a little bit and cause a little slop.
My elevator halfs did not come back to center either way.
After replacing with the ball-bearings, they are always dead center.

what is a Mk dual elevator coupler?

http://www.gatorrc.com/mk/mk dual coupler.htm

sorry the link won't work due to the spaces, you will have to cut and paste the whole link in the last post.

http://www.gatorrc.com

thanks ....

Any opinions on the Sullivan elevator spliter:

http://www.sullivanproducts.com/ContSysAccMainFrame.htm
Scroll about half way down the page.

Does this quallify as a "standard y-rod" system.

I have a 2-56 size one. It seems quite strong and secure and permits a wide range of off axis motion by the split elevator rods.

Hi all.
I am impolite with because it is different from almost opinion. Because there was following weak points, I stopped using MK dual elevator coupler for my 2m airplanes.
1) Weight becomes a little heavy.
2) Play will be caused in some joints.
But, a delicate handicraft should be necessary when the standard Y-rod system is adopted. However, I use the Y-rod system of easy structure preferably.
Thanks.
kobayan

What is a "standard Y-rod".

Of course, I can imagine what everyone means by Y-rod... it's the details of "standard" that I am wondering about.

The expression of the "standard" may not be right. �@Forgive me because it is poor at my English.
Two piano lines were glued at the tip of a long stick of balsa.
I think that it is the same as your probably imaging it.
It will probably be good Y-rod when sliding and so on is adjusted in the high precision before sticking a bottom board of fuselage.

kobayan

Thanks kaboga. MarkNovack also used the term "standard Y-rod"... so I am curious if everybody has the same view of what "standard" means in this case.

Jim,
The sullivan product (split elevator, double ball joint) will do the job for most applications for smaller size w/ 2-56, 4-40 for larger size.

For my plane, I did not want to use the product because it has two moving pushrod connected to actual elevator pushrod.
My plane was an ARC, so it didn't come with anything installed. It was really hard to put in the elevator pushrod of nearly 25 inches long. Then add 2 more of short pushrods to come out of the fuse for the elevator halves?
This thing also move side to side and is hard to support in a long size.

Here are things to consider.
if you mount your elevator servo upright and use Y-pushrod, the pushrod does not always move straight line at the servo end.
That is, the link on elevator side is moving in a circumference of a circle. This will cause the two elevator halves to move slightly different angle.

If you have a 3D type plane with split elevator using y-pushrod for elevator halves and single upright mounted elevator servo, you can find out what I am trying to explain here.

Smaller planes with smaller movement at the servo end do not show a lot of differences, but if your elevator servo moves a lot of angle, you will be able to see it.

I use MK bellcrank to prevent this from happening.

Another way to prevent this is to support the Y-pushrod at both ends so that the pushrod does not move side to side. This will cause a little bit of binding on servo end if used with large servo horn with large movement.

The other way is to side mount the elevator servo so that the pushrod does not move side to side.

Pesonally, I don't see a lot of weight differences in my case since the plane balances well with current setup.

checking up the linkage every season as a preventive maintenance helps avoiding any failure at the bellcrank.

Even my setup with Carbon pushrod and MK bellcrank also has foam support in the middle of the pushrod to prevent the pushrod vibration. Absolutely 0 slop. Very precise movement with entire linkage with ballbearing connectors.

It is your choice to choose which way to set your elevator.
This is just my choice of setup.
Hope this helps.

Thanks patternflyer. Yes, I can see that the need to restrain the servo rod so that no out-of-plane motion occurs is important, and complicates matter if a high degree of precision is important.

I thought about that in my case (a small 40 size plane) and concluded it would be too small to worry about.

Indeed, side mounting the server seems like the simplest solution.

Mr.PatternFlyer
Your opinion appreciates being majority. Someone thinks that Y-rod is difficult. That first reason is because the inside of fuselage of ARF can be hard to see.
Well, I will teach the way that linkage of Y-rod is easy for the people of being difficult.
First, the hole of 3mm diameter that it passes through Y-rod is made on both sides of fuselage near the tail.
Make a hole in accordance with the direction which Y-rod is passed through, the position.

Pass through the long plastic pipe of 3mm diameter from the outside of that hole toward the center box of fuselage.
Pass it through the other hole as well in this method.
Put 2 piano lines of Y-rod in the pipes each which passed to the inside about 1 inch each.
Pull it outside the fuselage with a balance doing two plastic pipes.
Then, Y-rod is supposed to be pulled in these.
If it is devised more, the hole whose it is thin will be able to pass, too.

kobayan

MK elevaltor crank on a G-trick. Isn't really nessessary.
I've been flying one for 3 years... it's precise.. but not anywhere near Hydeout/Alliance even Focus precise! See it for what it is, a damned nice Sunday pattern/3dish .90 model.
I use a 4/40 Y rod supported inside and a decent 7kg/fast Futaba servo. The fact thyat the Stab and/or wing are non ajustable will cause you far greater heart ache than an unnoticable differential on the elevator halfs!

Kobayan,
Well, thank you for reminding me the method. I did that way for my small EZ topline 50. I used antenna tube for this purpose.

Bla Bla
I agree.
Still, I am using the bellcrank to make it easier to maintain for my case and didn't want to take any chance of slop. My fuselage is about 2.5" wide where the elevator pushrod exit if I use Y-pushrod. I also have no way to add physical supports for the pushrod since the kit was an ARC.

Also, for those who are using MK Bellcrank.
I have a question. Kinda hard to explain with words, but here goes.

Do you screw the body of the bellcrank parallel to the fuse or perpendicular to the thrust line?

I mounted the MK Bellcrank parallel and used small washers on the rear holes where the screws go in. Looking at from side of fuse. Top of the picture.

From the top or bottom of the fuse: Bottom of the picture
since the fuselage is tapered, when I tightened those four small screws, the actual out side arms of bellcrank was not perpendicular to the thrust line. It actually was about 30 ~ 45 degrees to rear or front (I just don't remember).

Without the washers, my elevator servo buzzed all day because of the binding? it caused. Now there is none.