Rudder Alignment for Rigging

[whee]

I aligned with the vertical stab when the pedals are neutral, but that didn't work out exactly, I needed a small trim tab on the rudder.

Couldn't this be solved with adjusting the turnbuckles and maybe the springs? After rigging the Luscombe we had to ride the right rudder but we were able to fix it by adjusting the rigging.

[Zzz]

I aligned with the vertical stab when the pedals are neutral, but that didn't work out exactly, I needed a small trim tab on the rudder. BUT, that doesn't align it with the axis of travel of the aircraft, it's still largely offset, just not quite so large as the the vertical stabilizer's native angle.

So how would you do it if you had to do it again?

Whee, have you seen the Steve's Aircraft rudder trim system for Pacers?

[Mark Moyle]

Pacers/Tripacer rudder pedal alignment is accomplished with a multi-hole brackets on both rudder cables at the rudder horn... On a Bearhawk....I'd use a couple turnbuckles. To trim the rudder, standard practice is to twist the rudder by bending the portion of the rudder above the vertical stabilizer at the leading edge point just above the leading edge of the vertical stabilizer.


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[Bcone1381]

My knowledge level is very low so I will probably be asking a very stupid question.

Why not rig the rudder so that rudder pedal travel provides full travel to the rudder. Then when the flight testing begins, adjust an external rudder trim tab to provide coordinated flight in the cruise configuration. After this has been accomplished re-adjust the ruddr pedals via turn buckles to achieve a symmetrical rudder pedal position.

[Battson]

That is exactly how I approached it. Maybe I used a very stupid approach? :P Haha. What you said makes sense to me.

[Battson]

Couldn't this be solved with adjusting the turnbuckles and maybe the springs? After rigging the Luscombe we had to ride the right rudder but we were able to fix it by adjusting the rigging.

I would always balance it aerodynamically, to solve the out of trim condition. Hopefully that should keep the aerodynamic forces more closely balanced over a wide range of airspeeds, and keeps the mechanical forces on wear-out components neutral too (such as cables and fairleads). I imagine that if I used a spring-tension adjustment, the spring would be be too powerful at low speed, and too weak at higher speeds.

Yes the pedals could be realigned using the turnbuckles I have, but that would require a duplicate inspection and sign-off. It's such a minor thing, I don't actually notice where the pedals are, just what the plane is doing. So no need to adjust them really, for me.

[whee]

Whee, have you seen the Steve's Aircraft rudder trim system for Pacers?

I have, learned about it from the thread you posted a while back. I think it looks like a great idea and would be very useful with a big engine where you might cruise at really low power sometimes and high power other times.

I agree Battson, things should be balanced aerodynamically. I think this can be accomplished with rigging, at least it was on the Luscombe. If I can't get it with rigging I'll bend the rudder like Mark described.

[alaskabearhawk]

Kelly Babin installed that rudder trim system in his project and I think Mark Moyle is planning on putting it in as well. I haven't heard much from Kelly in quite a while.

[whee]

So did we ever come to a conclusion? 30* travel left and right from center or 30* travel left and right from in line with H-stab.