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  #11  
Old 03-17-2014, 11:40 AM
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longranger longranger is offline
 
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The rudder hinge brackets on my RV-7 vertical stab have a slight fore/aft misalignment as built, but there is still some flexibility in the lower end of the main spar where it will attach to the fuselage. My plan is to bolt the rear spar to the fuselage, then center a tight nylon thread in the end brackets, and flex the spar fore/aft until the thread centers in the center bracket. Then clamp the forward VS attach in that position and drill.
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  #12  
Old 03-17-2014, 11:53 AM
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Toobuilder Toobuilder is offline
 
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Back to basics:

If the bolts all drop in, and the rudder swings freely, then the basic geomety is correct. After you tighten down on the ball and force it to rotate (do its job), then you have a problem? Then you have a partially locked ball. With the rudder off, can you swivel/rotate the ball by hand? If not, you have corrosion, hardened preservative, or a failed ball.

Any chance you simply stuck a bolt or screwdriver through the ball like a "T handle" when you screwed the rod end in the first time? if so, there's a good chance you dinged the races and locked it up.
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Last edited by Toobuilder : 03-17-2014 at 11:55 AM.
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  #13  
Old 03-17-2014, 02:34 PM
Rupester Rupester is offline
 
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Default Couple of things ...

First , I assume you're checking the counterweight at the top of the rudder, to assure it's perfectly parallel to the top of the HS. That's a pretty close fit when aligned correctly; it bears close watch.
Second, another good check on your bearing and pivot bracket alignment is to drop a string down through. Any misalignment shows up in a hurry. That simple check helped me a ton at that phase.
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  #14  
Old 03-17-2014, 02:56 PM
Michael Burbidge Michael Burbidge is offline
 
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Default More info...

The ball moves freely. I bought the tool from Avery for tightening rod ends. So I did not use a screw driver. I have put a straight edge to the brackets. Bolts drop in to the bracket/bearing with almost no persuasion.

The counterweight at the top is parallel to the top of the HS, at least by sight. I will measure with a ruler just to be sure.

I will try the string through both the brackets and rod ends, and I will try some grease on the rod end bearing.

Thanks for the tips,
Michael-
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  #15  
Old 03-17-2014, 03:02 PM
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Mike S Mike S is offline
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Quote:
Originally Posted by Toobuilder View Post
Back to basics:

If the bolts all drop in, and the rudder swings freely, then the basic geometry is correct. After you tighten down on the ball and force it to rotate (do its job), then you have a problem? Then you have a partially locked ball.
Or, the action of tightening the nut is distorting something in the mounting brackets.

I would check the ball free motion first, easier to do. If that is not the problem, try tightening one nut only------see if it still moves easy. Then try backing that nut off a bit, and try another ETC. If that doesnt find the issue, try again, but leave the first nut tight.

You are really close, just need to find and eliminate this gremlin.
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  #16  
Old 03-17-2014, 03:17 PM
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Quote:
Originally Posted by Michael Burbidge View Post
The ball moves freely. I bought the tool from Avery for tightening rod ends. So I did not use a screw driver. I have put a straight edge to the brackets. Bolts drop in to the bracket/bearing with almost no persuasion.

....-
Another easy alignment check -

Drop in the upper and lower bolts - move the rudder hard over left or right - see if the middle bolt will still drop in with the deflected rudder.
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  #17  
Old 03-17-2014, 03:26 PM
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F1Boss F1Boss is offline
 
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Default another easy check

Hey Mike:

You say the bolts drop in easily with the rudder in trail. Try turning the rudder to full lock and check if they will still move freely. If not, you have a pivot axis alignment problem. If they are still free, then you have a rod end ball stuck, or you have a vertical alignment problem with one of your pivots. Since the rod end ball can tolerate some degree of misalignment, you can tweak the steel brackets on the fin spar up or down to get things 'just so'.

If you have a rod end that doesn't want to turn as required, try washing it out and re-greasing it. I have found more than one brand new frozen bearing in my inventory!

Carry on!
Mark
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  #18  
Old 03-17-2014, 04:57 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by Mike S View Post
Or, the action of tightening the nut is distorting something in the mounting brackets...
Possible, but those steel mount brackets move around a whole lot without much complaint. I've seen them deflected out of plane by an eigth inch or more (visable Z bend), yet with no binding.

As many have pointed out, doing the top and bottom only, and seeing if the middle bolt will still drop in at all deflection angles will tell the tale of alignment, but it seems the thing locks up right away, which seems to point toward a tight ball.

This situation is a strange thing though
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  #19  
Old 03-17-2014, 05:00 PM
AaronG AaronG is offline
 
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If the rudder swings freely with all the bolts installed and no nuts, I suspect it is not alignment. This narrows it to a bad bearing, or more likely a pinching of the rod end. Are the ears of the bracket parallel when the bolt is tightened, or bent slightly inward? With the bottom nut tightened, move the rudder, and look for interference between rod end (other than the bushing itself) and the bracket structure. If you see any interference, add washers between the bushing and bracket, to eliminate this interference, and drive the bracket to be parallel.

Aaron
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  #20  
Old 03-17-2014, 05:07 PM
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Toobuilder Toobuilder is offline
 
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Good point. The rod end should contact the hinge bracket ears on the ball ONLY.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
PA-20-inspired "family truckster" -in work

Last edited by Toobuilder : 03-17-2014 at 09:09 PM.
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