Electric Elevator Trim Rod Length

[esjacoby77]

I can't find any instructions for cutting the elevator trim push rod to the proper length. Is it as simple putting the trim tab "in-trail," setting the servo to the middle of its travel, and measuring between the two?

I'm probably over thinking this, but what methods have people used to measure/cut this rod to the proper length (or did I just completely miss something in the plans)?

 

[sglynn]

trim push rod length

3 1/8 inch

I just did mine. I installed the servo and then with a battery ran the servo to all the way in and installed the two end pieces. I turned one end piece onto the screw about 3/4 of the way. Then holding the tab with full deflection down I cut the screw to length so that it will go 3/4 of the way into the other piece. You could also do this with servo at full out and just hold the tabl full up and cut the screw to length. But what is full up?

Then I ran the tab up and down with the servo and battery, checking clearance and deflection. I get about 1.2 inches of stroke from the servo and about plus 30 minus 20 degrees deflection of the tab which seems slightly (5 degrees) less than the plans call out. I'll end up adjusting after flying starts. I'll probably want more down tab which will give more up elevator, and nose up for slower speed during final approach to landing.

 

[esjacoby77]

Sounds like my plan wasn't too far off the mark. Thanks for the measurement and description of your method.

 

[Maxrate]

3 1/8 inch

I just did mine. I installed the servo and then with a battery ran the servo to all the way in and installed the two end pieces. I turned one end piece onto the screw about 3/4 of the way. Then holding the tab with full deflection down I cut the screw to length so that it will go 3/4 of the way into the other piece. You could also do this with servo at full out and just hold the tabl full up and cut the screw to length. But what is full up?

Then I ran the tab up and down with the servo and battery, checking clearance and deflection. I get about 1.2 inches of stroke from the servo and about plus 30 minus 20 degrees deflection of the tab which seems slightly (5 degrees) less than the plans call out. I'll end up adjusting after flying starts. I'll probably want more down tab which will give more up elevator, and nose up for slower speed during final approach to landing.

Steve,

Great post. What did you use to cut the rod so as not to "screw up" the threads..

THX,

 

[sglynn]

Cut Elevator Trim Tab Rod with Hacksaw

I cut it with just a normal hack saw. First I put the nut on the rod. After cutting I polish the end of the rod on the scotchbright wheel. This removes any burrs. Then I turn th nut off the rod and that cleans out the threads as wheel. Works fine.