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I was just about to close my old A model flaps up when I noticed that the new B Drive Rib Assembly is 3/4” closer to the fuselage than the A model rib was. Of course I already had the flaps ready for the A model before I decided to ‘go B’.

How have folks handled this? If I just put the B rib where the B plans say, I have nothing to rivet the front of the rib to since I trimmed the skin for the A drive rib (sticking out into the rear spar area), not to mention a bunch of holes from the previous rib. Can the control rod be attached with the rib in the old A position using a stand-off/longer bolt? Seems that might be prone to failure.

Any advice appreciated!

SonAl:

I didn't see any responses to your question posted on 9 Nov, so thought I would chime in late. I had one flap completed as an A model flap before I started my conversion, so I removed the existing inner most rib with the flap drive bracket, drilled lightening holes in the removed rib, and reinstalled it without the bracket. I then installed an additional rib with the new B model flap drive bracket per the b-model plans, which, as you indicated, is slightly inboard of the A model inner most rib. Finally, I cut a small sheet metal plate to install on the front of the new B model rib and bracket to fill the cutout where the A model bracket had protruded forward from the flap.

I built the remaining (second) flap per the B model plans, but added an additional rib where the A model inner most rib would have been to ensure both flaps were identical. The additional rib was lightened and drilled exactly like the one in the other flap, again to ensure both flaps were identical.

For reference, you can look at my Kitlog Pro Log at "http://www.mykitlog.com/scripture" looking specially at the postings from 2/28/17 and the postings around that date. Looking at the log, I am very behind in updating it but think what you are interested in is there. Hope it helps....

Thanks very much, that was exactly what I was looking for.

One question, did you secure the small plate on the front of the new B rib to the old A rib with a bracket? Sort of like the aileron counterweight ribs....

Al Arbuckle
Sonex 617

I'm away now so can't verify, but it certainly wouldn't hurt. I know I doubled the small plate but can't remember if it was for proper alignment and stiffness, or to tie it into the other rib. Since the plate is so small, I think either would be acceptable.