PatternFlyer
Posts: 793
Joined: 5/11/2002
From: Pittsburg,
KS, USA
Status: offline
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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.
< Message edited by PatternFlyer -- Feb 12 2003 2:48AM >
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Mk dual elevator coupler on G-trick? - 
