False rib's

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False rib's

Postby Gary H » Mon Jan 29, 2007 11:40 pm

The false ribs are about 1/4 inch higher than the wing ribs, is this right?? I talked to Jamie at Just today, he said the wing was designed that way. It seems like it is going to look funny not to say changing "part" of the wing foil. Any feed back would appreciated . Kit #106   :lol:
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Postby DaveU » Tue Jan 30, 2007 1:40 pm

The wing false ribs are a little taller than the ribs, but once the fabric cover, the reinforcing tape and the finish tapes are on the difference is less than 1/8".  The way the fabric swoops down  between the ribs and false ribs, I do not think it has an effect on the airfoil shape.  

I did use a anit-chafe tape on the false ribs, and there is a 1" finish tape on the false ribs.

Dave
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Postby Gary H » Tue Jan 30, 2007 1:53 pm

Thanks Dave, guess this is correct. I have covered a lot of planes but this is a first for me. I looked at a lot of pictures, you can see the false ribes sticking up but if that's the way it's supposed to be then that's the way it is. I'll be putting the flaps and ailrons on this weekend. The engine (3300) should be here this week to.
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GW  :D
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Postby dauckjl » Tue Jan 30, 2007 3:07 pm

Hey guys,

I remember hearing someone saying at OSH that that shape with the false ribs higher actually give more stability to light aircraft.  I can't remember who it was but they seem to hand le well so I'll take their word for it.

Happy building,
Justin
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Wing False Ribs

Postby Wes » Mon Jun 09, 2008 2:54 pm

Well, after more agonizing, I finally settled on the solution shown in the pic.
I wasn't happy about the 'sharp' edged false ribs even with tape over them and I wasn't quite ready to take on all the glue and sheet metal of the leading edge wrap solution, although I think it looks super.
So, I ended up with a 7/8 in wide alum' strip glued to the top of the slightly reshaped false ribs supplied with the kit. I had to build a special fixture to do this gluing work (one at a time!) on the 30 ribs, but the end result is OK. I reshaped the leading edge of the supplied ribs to make them sit down closer to the L.E. spar and match the contour of the main ribs a little better.
After all the glueing and trimming and fitting, it probably would have been easier to do the leading edge wrap thing, -- Oh Well---

Wes
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Postby Johnny C! » Mon Jun 09, 2008 10:11 pm

Hey Wes!

Those look great!

How much will a set cost me? :D

I have the mailing envelope written
& my pen to the check book!

Oh yea, what took you so long?

Later!

John
There are many things that happen really fast when you are
flying an airplane. There is no sense in rushing any of the others.

I would much rather be looking down at the runway, than up at it.

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Postby pdeinin » Tue Jun 10, 2008 12:22 pm

Those look like beautiful work.  My only concern is the question of how reshaping things affects the lift from the wing.  It looks like you made them match the profile of the main ribs.  That would make the fabric dip down lower between the false ribs, effectively making a thinner wing cross section.  This might increase speed, but also increase stall speed.  Troy said someone else did something like that and it worked fine, but he thought it influenced the lift on the wing.
Prescott
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Capped False Ribs

Postby Wes » Tue Jun 10, 2008 7:22 pm

John,
Thanks.
But after glueing and trimming 30 of these buggers, one at a time, I don't think I'll live long enough to build another set.
I would be willing to loan out my fixture and metal pattern for the reworked ribs.



Prescott,
I don't know how to evaluate any potential change in lift profile, but my reasoning for justifying the change went something like;
-original ribs needed something to distribute the fabric load since they stood up so 'proudly' above the real ribs profile.
-the 'average' cord profile is established by the main ribs, so the majority of the lift profile should follow that shape.
Only controlled flight tests will tell the difference, so I will have to wait till it's in the air and flying next to an 'unaltered' wing.

Wes
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Postby Johnny C! » Thu Jun 12, 2008 4:26 pm

Guys!

I am not a aeronautical engineer, but
I can't see how that modification would
have any adverse effects.  The fully
wrapped leading edges that some are
constructing, is, in my opinion, just a
little further down the same road.

However, I am intending to use the
false ribs as supplied with the kit.


Later!

John
Last edited by Johnny C! on Mon Aug 25, 2008 9:31 pm, edited 1 time in total.
There are many things that happen really fast when you are
flying an airplane. There is no sense in rushing any of the others.

I would much rather be looking down at the runway, than up at it.

Duane Sorenson & Rick Norton Gone West 6/8/09. Godspeed
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Postby Dave Krall CFII SEL SES » Mon Aug 25, 2008 5:52 pm

Johnny C! wrote:Guys!

I am not a aeronautical engineer, but
I can't see how that modification would
have any adverse effects.  The fully
wrapped leading edges that some are
contructing, is, in my opinion, just a
little further down the same road.

However, I am intending to use the
false ribs as supplied with the kit.


Later!

John
 (2 threads going on this subject)

The attachment of upper wing fabric to the false ribs was just discussed with the waterborne paint people and they told us to put the main fabric sheet over the wing, shrink it, then hot glue a tape on TOP of the wing fabric along the false rib so that the glue penetrates and adheres to the false rib's edge. Anybody else do it this way?
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Postby John S » Fri Aug 29, 2008 3:01 pm

I plan to use the original false ribs as supplied, and apply anti-chafe tape on the their top and bottom surfaces.  After the fabric is on and shrunk, I plan to apply finishing tapes over the false ribs.  

My question for the forum is:  How long should the finishing tapes be?  Should they extend from the wing leading edge, over the false rib, back to and around the trailing edge, then back to the leading edge?  Or should the tapes only extend to the trailing end of the false rib?

Thanks.
John S
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False rib tape

Postby Roger » Fri Aug 29, 2008 5:23 pm

Take a look at the picture from Wes, above. I terminated my tape just about wher Wes has the front of his false rib, and on the back side, I just blended the tape in maybe an inch or two behind the back end of the rib, and rounded the end of the tape. When it was primered and painted, it's barely noticeable.
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