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-   -   "Sticky" Ailerons (https://vansairforce.net/community/showthread.php?t=84332)

Andrew M 03-26-2012 02:20 AM

This has a name
 
Quote:

Originally Posted by curtis (Post 643261)
When you get to the point where you feel the drag check and see if you can still twist/rotate the push-pull tube freely. If not, You may have the rodends clocked so they bind up towards the end of the travel by rubbing on the bellcrank.

I picked this up while working on DC-6's. It's in the manual as "check twizzle of rod ends after installation of control and adjust as necessary prior to locking nut for rod ends" I'm adding a lot of words to make it clear, actually it read something like "...check twizzle";)

DanH 03-26-2012 05:53 AM

Quote:

Originally Posted by ArVeeNiner (Post 643299)
With the large tubes that run from the sticks to the bellcranks disconnected, the ailerons to bellcrank runs have no stickiness.

Question....where do you disconnect them, at the outboard end of the big tubes?

Second question....are the aileron stops installed and is the measured surface deflection within spec?

Quote:

...and my tech counselor says its nothing to worry about especially since the air loads will easily over come it.
No form of control binding is acceptable.

schristo@mac.com 03-26-2012 05:55 AM

Rivet drag on aileron attach bracket...
 
Check to see if you have a very small bit of contact near full deflection on your aileron attach brackets from a rivet...

ArVeeNiner 03-26-2012 10:21 AM

Quote:

Originally Posted by DanH (Post 643345)
Question....where do you disconnect them, at the outboard end of the big tubes?

Second question....are the aileron stops installed and is the measured surface deflection within spec?



No form of control binding is acceptable.

1-I disconnected at the outboard end.

2-Stops are installed and deflection is within spec.

I just got off the phone with Van's. They said if there is an issue with the heim joint touching the weldment it's most likely at the control stick end. They said there are very small washers that are added between the joint and the weldment to alleviate this issue. I remember installing these washers because they are such a pain but I will double check anyway.

He was also saying that if this is an issue he's know people that had to relieve the weldment a bit to clear the joint.

I won't be able to get out there until Tuesday but when I do, I think I will:

-Move the stick as it is now with the outboard ends disconnected to see if the stickiness is there. I don't remember making that check over the weekend. Of course the geometry will be different than when they are attached so I'm not sure how much this will buy me.

-Then I will hook up the outboard ends and disconnect at the sticks then move the ailerons to see if it is gone.

-At some point I was thinking of loosening the heim joints, take the ailerons to their limits, then tightening the joints at that point.

The guy at Van's actually went out to check on their birds and he said that, at least for the one he tried while I was on the phone with him, there was a small bit of stickiness at the extremes.

Some things we were kicking around over the weekend were maybe the mechanical advantage of the bellcrank is less at the stops (confirmed by Van's) and the airloads will make this a non issue in flight (also confirmed by Van's). Van's said this is not a safety of flight issue.

Regardless, I'm with you on this Dan, I want to chase this down and get it cleared up. I want my controls like butta at all extremes if that is possible.

Regarding rivets, I checked those and they seemed to clear.

I'm thinking I'll find the smoking gun during the "twizzle" check but we'll see.

I'll send out an update later this week. Thanks again for all the help.

tsneidin 03-26-2012 10:54 AM

Not sure if this was mentioned yet, but my main aileron tubes would just barely touch the seat ribs in the fully deflected position. I just filed a little off the rib and all was good.

Lars 03-26-2012 04:18 PM

newbie dumb*$$ mistake
 
I went to my hangar at lunchtime (lucky me; it's only 10 minutes on country roads from my office) and continued obsessing.

Then had an aha moment, followed by feeling like a moron.

When I installed the ailerons on the wings several years ago, I had failed to observe the admonition in the plans to shim the outer hinge with washers or even a fabricated spacer as necessary to remove side load. Instead, I'd assembled them with the exact washers shown in the plans. Upon loosening said outer AN-3 bolt at the outer end of each aileron, then removing the washers, the problem became instantly obvious. The hinge bracket wanted to be somewhere else. After some bending, fussing, getting down on my knees and scrutinizing, I reassembled. The control stick now falls to the side once either aileron travels upward more than 10 degrees or so.

Not sure how I managed to overlook that, other than being a relative newbie when I assembled the ailerons the first time. Contrast that with the nearly 30 hours of increasingly frustrating obsessing I did over elevator bind. But my elevator floats freely as a result, even with the added drag of an autopilot servo. Despite that effort, I completely overlooked the ailerons and convinced myself that the stiffness was due to the roll servo when I installed the wings a couple of months ago. Duh.

jthocker 03-26-2012 09:21 PM

Glad you figured it out Lars! :D

Lars 03-26-2012 11:11 PM

Quote:

Originally Posted by jthocker (Post 643651)
Glad you figured it out Lars! :D

Thanks, Jon. You will like my reinvented controls much better!

jimgreen 03-27-2012 12:23 AM

Flap hinge pins too long?
 
A strange one that I had was caused by flap hinge pins that were too long.
At nearly full aileron deflection the aileron hinge bracket was touching and bending the end of the pin. I still got full deflection but an increase in resistance.

ArVeeNiner 03-27-2012 10:11 AM

Quote:

Originally Posted by Lars (Post 643574)
or floats freely as a result, even with the added drag of an autopilot servo. Despite that effort, I completely overlooked the ailerons and convinced myself that the stiffness was due to the roll servo when I installed the wings a couple of months ago. Duh.

Yea I had a false aha moment concerning the roll servo. Good that you found your problem easily.

I can't wait to get out to the hangar after work to take another look at mine.


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