Author Topic: Rib differences?  (Read 167 times)

Offline jrbirdman47

Rib differences?
« on: September 10, 2019, 08:09:53 AM »
Maybe a little late in the game, but I built ribs according to the Iron Designs plans/ videos, (And they were great! Really made putting things together go well and the full sized drawings were a big help)

However, now that the wing is finished I notice that some photos of ribs have three "verticals" aft of the rear spar: One large one that ties the aileron spar to the ribs of those so designated, one about 3" tall behind it, and one about 1 1/2" tall just behind that one, a few inches forward of the trailing edge.

Some photos show ribs with the "aileron spar vertical", and then, ONLY the smaller one, but not the second one as indicated above.

My ribs, built according to the Iron Designs plans do not have the smallest "vertical" just ahead of the trailing edge. I also note that Leonards plans do not show such a thing in the aileron 3D view, (Which may simply be an omission for better clarity, I don't know), but definitely show it in the "tape together" rib plans that I have.

So now I am left to wonder what is "correct", or if they are all correct, and if my ribs are OK the way they are or not.
Seems like the folks at Iron Designs are pretty smart fellows and have engineered some good stuff, so I think that if the last "vertical" is omitted, they must have good reason for doing so, and perhaps there is a weight vs. strength tradeoff there since their use of "K" blocks to form the aileron well added a bit of weight.

Or, I could be overthinking this.......

Any comments and observations are appreciated!

Thanks!  Rick

Offline scottiniowa

Re: Rib differences?
« Reply #1 on: September 10, 2019, 02:53:37 PM »
Maybe a little late in the game, but I built ribs according to the Iron Designs plans/ videos, (And they were great! Really made putting things together go well and the full sized drawings were a big help)

Iron Design here- on Sheet 3, it shows the rib fixture jig, with this very last short vertical in place. But true to your word, I do not have it in the full rib drawing.
 I wish I could tell you the exact date, but I started adding a clarification sheet, (if you have a sheet with color it is in there, show this short vertical in better detail)


However, now that the wing is finished I notice that some photos of ribs have three "verticals" aft of the rear spar: One large one that ties the aileron spar to the ribs of those so designated, one about 3" tall behind it, and one about 1 1/2" tall just behind that one, a few inches forward of the trailing edge.
this short vertical should be the same for each rib and could be added if the general consensus deems this necessary, I know this was confusing and was the cause for my doing these supplementals in the first place.

Some photos show ribs with the "aileron spar vertical", and then, ONLY the smaller one, but not the second one as indicated above.

My ribs, built according to the Iron Designs plans do not have the smallest "vertical" just ahead of the trailing edge. I also note that Leonards plans do not show such a thing in the aileron 3D view, (Which may simply be an omission for better clarity, I don't know), but definitely show it in the "tape together" rib plans that I have.
that is my only defense, though I never mind to be corrected if we all learn about things. Was simply it was shown both ways as you noted. Both with, and without.  I guess, but I don't know, is simply, "did fabric tighning effect this area?" for others.  For us, it did not.

So now I am left to wonder what is "correct", or if they are all correct, and if my ribs are OK the way they are or not.
Certainly a good question,  if in doubt and not covered, the answer is simple. with a addition of this little vertical.  Many have been built without.

Seems like the folks at Iron Designs are pretty smart fellows and have engineered some good stuff, so I think that if the last "vertical" is omitted, they must have good reason for doing so,
I wish I could say this was a engineered plan, like stated above, it was shown in one area, and then not in another area, just like the full plans. I will say the unsupported span in this area is not 1/10" different than any other area.   And then in later years, it was shown as revision B, sent with plans.

and perhaps there is a weight vs. strength tradeoff there since their use of "K" blocks to form the aileron well added a bit of weight.
These K blocks, were truly done because they do so much good for so little extra work and weight much like you just said.

Or, I could be overthinking this.......
never hurts to ponder things like this, both to your self and forums.
Scott of Iron Design L.L.C.


Any comments and observations are appreciated!

Thanks!  Rick
best email address:  irondesignairparts@gmail.com

Offline jrbirdman47

Re: Rib differences?
« Reply #2 on: September 10, 2019, 04:34:56 PM »
Thanks Scott, That all makes sense. The wing isn't covered yet, and I think I may just glue a 1" wide piece of 1/8" plywood to one side of the upper and lower cap strips at that position. It's the quickest, easiest fix I can think of and should easily approximate the strength and weight of the 1/4" square vertical. Having built all the components for 4 wings, Ive cut out enough little triangular gussets for one lifetime. :P

Again, thanks for your efforts in design. I REALLY liked building the ribs that way and was able to designate a rib for each position and build all the ribs complete with the extra parts necessary and did virtually nothing else except slide them into place and glue them to the spars. Studying the videos helped me understand how the parts all inter-related and made the sequence of construction easy.

Eagle on!

Rick