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ACHIEVING AILERON RIGGING ANGLES

Graham

Active Member
I am rigging my RV6 ailerons and have been unable to achieve more than 29-30 degrees nose up.
Admittedly this angle is within allowable limits of 25-32 degrees for TE Up aileron, but I believe that one should be able to achieve the maximum limit even if one doesn't use it all.

After much hair tearing I have found that the outboard hinge lower AN3 aileron attachment bolt is stopping aileron travel at approx 29-30 degrees. The bolt stops against the outboard aileron hinge bracket, and I may be able to file a small blend out in this fitting to compensate.

My question is: Has anybody else encountered this problem? If so what did you do about it.

Of course this may be a tolerance build up issue, e.g. My fittings may be slightly "oversize". However I imagine there are many RV's where the bolt head must be very close to fouling at full aileron travel. Like all issues the more of us that know about it the better off we shall all be.

Thanks.
Graham in New Zealand
 
29-30 degrees is fine as it is within the specified range.
I would NOT “file a small blend in the fitting” as you will be weakening it and way more of issue then not getting to full 32 degrees especially since 30 is just fine.
I would also make sure you aileron stops are set to have hard stop before the AN3 bold contacts the hinge fitting. If not then you may be causing damage to the fitting every time you go to full stick travel, which at the very least, is every time you fly at run-up when doing a full travel stick stir.
 
I found the same problem on the right aileron of my RV-8.

I used a Delrin bushing 0.66" dia on the inboard hinge's pushrod bolt to provide the TEU stop against the inboard hinge bracket. The diameter chosen was based on an average from multiple builders' reports. When installed, I found that an outboard hinge bolt head contacted the adjacent hinge bracket with the aileron at 29 deg TEU, leaving about 0.003" gap between the Delrin bushing stop and the hinge bracket on the inboard side.

As a check, I took the Van's drawing of the outboard hinge and rotated the aileron 29 deg TEU. This results in contact with the adjacent bolt head, consistent with what I encountered. Clearly the 32 deg TEU limit is not achievable with Van's design.

The clearances and interferences are very small, especially since I expect the design's tolerances are probably +/- 0.010" or higher. I looked at the outboard hinge bracket lug shape, comparing upper and lower halves, and decided to skim 0.010" off the interfering edge of the bracket, removing contact marks caused by the bolt head. This allowed the inboard Delrin stop to come into contact with its hinge bracket, as intended.

Alternatively, I could have increased the Delrin stop diameter by 0.010" and accepted the very small reduction in TEU travel.

In fact, I could probably have done nothing, since the flight loads on the aileron tend to open the outboard hinge gap as full TEU deflection is approached. However, this would still have left the possibility of a control sweep on the ground, or a curious passerby, causing contact damage to the hinge bracket.
 

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Gents,

Thanks for your most thoughtful replies.

I have blended approx 0.050" off the rear edge of my outbd aileron wing bracket at the bolt foul location, and that is good for more than 3 degrees improvement, which I can live with. I am a retired Aeronautical structure Engr so have considered the consequences.

Dave, it is interesting that you had the same problem. If possible I would like to see a photo of your Delrin stop, or a sketch.

Thanks
Graham Murphy
 
I basically copied Mickey's installation, from http://www.rv8.ch/aileron-stops/.

I used some 20mm Delrin rod, which I centre drilled 5/16" to make a bushing for the A-711 inbd upper spacer, it a very light press fit. I reduced its diameter by putting a bolt through the bushing, chucking it in a drill press and polishing with a fine file.

The spacer with the bushing added was then trimmed to length and installed following Van's construction manual process.

With the aileron full TEU, the bushing stops against the inboard aileron hinge bracket.
 

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