R

Rivethead

Well Known Member
I have a question that has been bugging me for months. When building my elevators I trimmed both counter balance weights. Of course the expected thing happened and the trim tab elevator dropped to the elevator down position when hung on the HS and of course the properly trimmed side went pretty much to neutral. So time goes by and I put the HS and elevators on the fuse for rigging. Once everything was rigged as in control sticks and push rods hooked to the elevator everything just naturally went to neutral. I could jockey the stick around and let go at any random point and it would always seek neutral. So now the question, is this condition what a builder is after or should the elevator be acting differently?
 
Unless you've got springs in the system, I don't think it will "seek neutral". You want them to be balanced as a unit (i.e. with the elevators connected to each other). In other words, when you give the elevators a nudge upward, they should travel the same amount as when you give them a similar-strength nudge downward.
 
No, no springs attached and they are bolted together. I had rigged the entire set up when I attached my stabilizer to the fuse. Everything is as it will be when final assembly is done save for this if it turns out to be a problem. In fact they very much did seek the neutral position. When I input full up and released they went to neutral and when full down input was given and released they again would seek neutral. Perfectly neutral. However when the push rod was disconnected and the elevators tied together via a bolt they went very lightly to the down position.
 
If you look at plan drawing #5 it will tell you that only the right elevator counterweight gets trimmed down. The left side is left intact to compensate for the added weight of the trim tab components. The elevators should be balanced after painting and with no linkage hooked up and not bolted together. They should balance when just hung onto the HS by the two hinge bolts. If you balance them separately, they will balance when together. It's just better to balance them separately to ensure the balance mass is countering the mass of the elevator that it is attached to. Otherwise you may have more weight than needed to offset from one side to the other and the surfaces will not be dynamically balanced.

Best to leave the weights on the heavy side. Small holes drilled into the lead will bring the elevators into balance. These holes are not noticable and easily touched up. You are balancing flying surfaces, not the control linkage.

Hope this helps.

Roberta
 
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