Friday, July 16, 2010

noserib dilemna

Most noseribs go in the exact middle of the space between the main ribs. Some are off-center to accommodate other hardware in the way - like the jury strut.

Does this noserib go inboard or outboard of the jury strut? According to the reproduction of the original parts manual, showing the built-up ribs, it goes inboard.

If I look at the post-WWII BC-12D owner's manual with the stamped ribs, it goes outboard of the jury strut, though snugged up to it.

That's not really an authoritative source, though, given this is a pre-WWII plane with the built-up ribs. On the other hand, take a look at that first picture, with the patterns of where the ribs used to be in the varnish. Those are the original spars from the factory, with a stamped serial number plate nailed into one spar. So the rib was actually outboard when it came out of the factory - despite the parts manual's indication - and the post-war planes kept that rib placement and made it official.

Do I restore to the documentation, or to the original condition?


  1. Put one rib on each side, then you're good to go whatever happens!

    (Don't you just love helpful suggestions like this?)


  2. I would say that the support just needs to be close to the middle of the gap. This should be the best way to support the leading edge material, and inboard vs. outboard makes little difference so long as the leading edge material is supported and is not deformed by the slant of said support rib. I would also check with whoever is going to be certifing this plane, as they may call for something like what Peter says, ie. double up support. I know not much real help either, I'm just a mechanics of materials geek, so I may be missing something important, esp. aero related.

  3. Pragmatically, well... it didn't fall out of the sky in the last fifty years. Prolly won't in the next fifty either.

    Frankly, I suspect it doesn't really matter. But Mr. P knows all... :)

  4. Just me, but I'd go back to the 'original' configuration...

  5. I'd go with original placement - two reasons:

    1) Like Jenny said - it flew that way for a lotta years that way; seems doubtful it'll fly any less the same way in future.

    2) Having been indirectly involved, a few times, in "that what the book says/shows" vs. how the guys who actually build the stuff (and know what really works, and is safe) do out in the shop - I'll tend (unless the shop guys are proven dodos) to go with how it got built.