Please explain.....

Someone "in the know" can answer this, I am sure.
The Sig 4" "black" bellcrank has been referred to as "self centering".
If it installed reversed (up line in front) what will be the effects, problems, etc., ??
Thanks!
Bill Little <><

A "self centering" belcrank is one with the arms at an angle towards the leadouts instead of being straight on the pivot axis. It makes no difference whether the front leadout is "up" or "down". It becomes "self centering" only because, as you apply input in either direction, it gives more leverage in the opposite direction and wants to return to neutral.

This may, or may not be good. Remember that you "must" then make sure the plane's controls are at exact neutral when the belcrank is or you will be working against it just trying to fly level. Fortunately, the effect of the belcrank is minimal compared to the pressure over the surfaces, but it is a "might be good"/"might not" situation.

Try it. You (may or many not) like it.

So it doesn't matter as to the "angles" of the arms?
ie.: "standard" they sweep away from the pilot, "reversed" they sweep towards the pilot.
Just asking for clarification in my own mind.
Thanks!
Bill

>So it doesn't matter as to the "angles" of the arms?
>ie.: "standard" they sweep away from the pilot, "reversed"
>they sweep towards the pilot.
>Just asking for clarification in my own mind.
>Thanks!
>Bill

On these "self centering" belcranks you absolutely must have the arms pointing towards you. Otherwise it will want to "uncenter", and you can also over run the arms where the leadouts get a bit tangled.

We always build with reversed belcranks, but have stuck to the "standard" kind. Still, there are some who use the others and like them. But they "must" be mounted reversed, with the arms pointing in towards you.

And, yes, we, also, use the forward arm as "up", but that is not necessary. I like Al's reasoning on this: "It might help and won't hurt."

Thanks! Question answered.
Bill

I've never seen that bellcrank but, all bellcranks are self centering because the leadout holes are inside of the pivot bolt. Which line is up depends if the control horn is on top or bottom of the elevator so, should not effect centering. Just don't flip the bellcrank over so the pushrod hole is on the inside or, your controls can lock under certain conditions.

Giffy

Thanks, Gif, but I got lost here. I routinely put the bellcrank in "reversed" (pushrod on the inboard side) and don't understand the lock up situation. (??) Not being obnoxious, just curious.
Thanks!
Bill

I have used the Sig bellcranks on several airplanes without a problem. I did not understand what they were and have always installed them reversed. Oh well!