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Flap bearing attachement question

az_gila

az_gila

Well Known Member
Flap bearing attachment question

RV-6 only - the RV-7s and up are different.

The Aurora CM-4MS "stud end bearing" at the flap end of the flap pushrod has a threaded portion that is 0.562 inches long.

I can't find the hardware callout for the nut on the stud, but I followed standard practice and used an AN365 nut and AN960 washer.

BUT

Material thickness (1/16 + 1/8) = 0.188

AN365 nut height = 0.312 to 0.328

AN960 washer = 0.063

This all adds up to 0.563 to 0.579 + a little extra for 4 layers of primer.

Not even a single thread showing above the nut. I can change to a thin AN960L washer but even that isn't really enough.

What did other builders do here?

Use no washer?

Use a thin AN364 shear nut? - but this does seem like a high stress location

Or switch to a MS21042 nut which is only 0.219 high?

ms21042.jpg
 
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Deviated -

az_gila said:
RV-6 only - the RV-7s and up are different.

The Aurora CM-4MS "stud end bearing" at the flap end of the flap pushrod has a threaded portion that is 0.562 inches long.
... (snipped down)
What did other builders do here?
Use no washer?
Use a thin AN364 shear nut? - but this does seem like a high stress location
Or switch to a MS21042 nut which is only 0.219 high?
Click to expand...

Gil - Think I installed an appropriate size nutplate on the flap itself (bracket) and torqued the CM-4MS to that. I'll double check but may have used a 'L' (thin) washer on the fitting side.

Did the torque set before it was pinned to the wing, too. (Wrenches are not easy to use in that space.)

Will be at the hangar in a bit and will double-check and also (Emailed you a few pics) and link to my build log.
(Reference http://www.mykitlog.com/garyc Wings section - entry for 10/8/2011)
 
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RViter said:
Gil - Think I installed an appropriate size nutplate on the flap itself (bracket) and torqued the CM-4MS to that. I'll double check but may have used a 'L' (thin) washer on the fitting side.

Did the torque set before it was pinned to the wing, too. (Wrenches are not easy to use in that space.)

Will be at the hangar in a bit and will double-check and also (Emailed you a few pics) and link to my build log.
(Reference http://www.mykitlog.com/garyc Wings section - entry for 10/8/2011)
Click to expand...

Thanks for the pics, but as you said you had to dis-assemble the bracket to get the nutpate attached.

I'm in final assembly with the flaps being the last of the control system to hook-up - it's a bit late for re-riveting...:)

And yes, I wish I had attached that stud bearing when the flaps were on the bench before installation on the wings.

Your nutplate solution is similar to the later RV-7 design, except they also moved the flap root rib to be a part of the stronger bracket.
 
Point made -

Sometimes the RV-6 (and probably prior models) seem to be a set of three steps forward and one step back to do something that was less obvious, intuitive or conflicted until the rivets are pounded and you sleep on it.

Been there and done that, too often. Getting real good at disassembly and salvaging scrap for another try.

Now I know what causes 'repeat offenders' to be so enthused.
;)
 
Spaced out

I used a spacer, a bolt, and a one of them rod ends with a hole in it. This was my solution for a slightly different issue than yours but should work for you too. I had to do this to get everything to fit as I had some alignment issue with the flaps being too far in/outboard (I can?t remember the details). Otherwise the pushrod line thru the fuselage would have been too off, etc. Note that the spacer is made from square stock with another flathead bolt above it to take some of the load as the bolt thru the pushrod end is cantilevered, which concerned me, and I preferred to overkill the design rather than find out the hard way (in flight) if long-term failure was going to be an issue. Yes, the spacer looks like it?s made of wood but that is only because it is made of wood. :) Seriously, the wood was a template, the final spacer is square aluminum stock.

flapspacer.jpg


I also used thicker round stock for the pushrod.
 
Arvey Fleur said:
I used a spacer, a bolt, and a one of them rod ends with a hole in it. This was my solution for a slightly different issue than yours but should work for you too. I had to do this to get everything to fit as I had some alignment issue with the flaps being too far in/outboard (I can?t remember the details). Otherwise the pushrod line thru the fuselage would have been too off, etc. Note that the spacer is made from square stock with another flathead bolt above it to take some of the load as the bolt thru the pushrod end is cantilevered, which concerned me, and I preferred to overkill the design rather than find out the hard way (in flight) if long-term failure was going to be an issue. Yes, the spacer looks like it?s made of wood but that is only because it is made of wood. :) Seriously, the wood was a template, the final spacer is square aluminum stock.

flapspacer.jpg


I also used thicker round stock for the pushrod.
Click to expand...


Interesting solution. A bolt and a similar CM-4M bearing as used at the upper end would need a 0.281 spacer to get the identical stock geometry.

I wonder why Vans didn't go for that option?

https://fci.thomasnet-navigator.com/cache/Geomstore/20160709-025557-04575249.pdf
 
page please

what page of the prints is all this bearing stuff on. i will not learn if i dont ask...19a? i found it after lookng in fuse section pg 40. is there a different part that can be used and not a fabricated extra part
 
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Billythekid said:
what page of the prints is all this bearing stuff on. i will not learn if i dont ask...19a? i found it after lookng in fuse section pg 40. is there a different part that can be used and not a fabricated extra part
Click to expand...

Page 40 has the bearing call out, which is the same for both manual and electric flaps. Page 17 shows the hole location in the flap bracket but no bearing detail.

Page 40 does not have the hardware call out for how the bearing stud is attached. This was the reason for my first post in this thread.

This afternoon I went ahead in a sweaty hot hangar and with a lot of fiddling, but not too many swear words, got the stud bearing attached with the MS21402 nuts I mentioned earlier and a single AN960 washer under the nut.
 
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