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Pressed Wing ribs

I also remember a story told by/or in a good book?? Farewell Nanook: Mary Oldham - Amazon.com about polar bear hunting, where she describes hearing the rib stitches breaking in turbulence(back in cotton days).. and yet not coming out of the sky..

She was the first? registered female big game hunting guide up here?.... she did not get a license the first year it was offered, because SHE HAD WRITTEN THE TEST :).. my stepfather used to work/fly for them, he has guide license #12
 
mike mcs repair said:
...to me, the most important thing they must do is keep the spars standing upright between compression members... if that fails you gonna come out of the sky...
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Mike it is the compression members which hold the spars upright in a Cub. The ribs are just going along for a ride. Of course they do help some, but the compression members are primary.
 
Longwinglover said:
Pete,

In retrospect, I think it was a statement and a question you posed that spurred my reply. The rib does actually do more than just give the fabric shape in that it is the structure underlying the fabric that transferrs the lifting force to the airframe. As to how the the load is transferred to each rib, it is by the rib stitches and transferred in compression from the bottom up.

John Scott
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Totally agree.

N86250 said:
Is there a reliable method for attaching fabric to carbon fiber ribs? Will the flange edge cut ribstitch cord like a pressed aluminum rib? Will the carbon fiber hold a screw or a fabric clip? Just glue? jrh
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I do not believe that properly installed rib stitch cord will be any more susceptible to "cutting" with a properly shaped carbon rib than an aluminum one. There should not be any relative motion between the cord and the rib which would be necessary to do some cutting. The reinforcing tape under the cord should hold the cord away from the rib edge. I think that it would be very interesting to try carbon ribs if there is enough weight advantage.
 
skywagon8a said:
Mike it is the compression members which hold the spars upright in a Cub. The ribs are just going along for a ride. Of course they do help some, but the compression members are primary.
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but when the spars get bent, that always happens in between the ribs.... they may look flimsy, but.... so they help "enough"
 
Compression members help in keeping spars in vertical alignment but the ribs do the job in the 3' to 4' spaces between the members.
 
hmmm.... you might be responsible for me getting a 100 ton press I
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asked my landlord if he had a bigger press for sale than my little 20 ton, he said no, but then remembered someone moving to lower 48 wanted him to sell their 100 ton homemade setup, will see if this pans out :smile: looks fun!
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bump...

Anyone got some good videos or links for press forming stuff, making dies, routing blanks and such????...

I did get the 100,000 lb press put back together after 6 or 7 weeks laying in pieces on my shop floor... now need to learn what I can do with it(how to)...

pictures of my first try doing a pressed cessna style nose rib with the rubber pad method.
I was quite happy with the finish part, compared to the original I tried to copy, especially for a first try, with a total of 1 hour 15 minutes invested start to make wood form to a finish part...
look in "press forming" album Picasa Web Albums - mike

some videos of routing blanks, pressing & making ribs & such I found on YouTube
https://www.youtube.com/watch?v=eZ062_wUWCE
https://www.youtube.com/watch?v=RA_a0pD5-UU
https://www.youtube.com/watch?v=RhG8gISbWMA
https://www.youtube.com/watch?v=mUSljM05pzo
https://www.youtube.com/watch?v=1Jx1I9MmPh4
https://www.youtube.com/watch?v=SYnX5-2m4HQ

https://www.youtube.com/watch?v=iY6Gbf_rOkY
https://www.youtube.com/watch?v=EWGAIVDpDLc
https://www.youtube.com/watch?v=jYHzPskP7fc


Later in this video, for showing how to make dimples..
https://www.youtube.com/watch?v=PUgXlYMLAkI

good supplier for urethane rubber in liquid http://www.dascarplastics.com (which the site is really is now owned by http://www.specialtyresin.com but the prices are better..)
 
skywagon8a said:
If you use -T3 there will be a fair amount of hand work involved to shrink the puckers which will be formed due to the compound shape changing.
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have not tried this yet, but in my mind, I bet if you make it a 2 step process you can get away without puckers, but the key is you will NOT press a truly FLAT(finished) (rib/part) shape at first, but more of a curved piece(where the curved flanges would normally make excess/puckers) just to get the flanges standing upright, then a second operation to flatten the part & pull/stretch out the excess(normal puckering material)

I might be full of it with this thought..., but will give it a whirl anyway...
 
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Mike,
The puckers become more of a problem when the radius of the bend gets smaller. Such as the nose of the rib. The excess materiel needs to be shrunk and is more easily done with -0 materiel. This is where the rubber comes in, holding and molding with the materiel while the press moves it down. The T-3 material tends to fold the excess which is not desirable. A long rib made of T-3 will tend to form in a long curve. In my view the mold would need to be made with a curve in it to compensate for the resistance to shrinking of the T-3.

One method of making the mold for T-3 use would be to make some dimples in the mold. This wouldn't look good on a Cub rib having the dimples in the cap strip.
 
added some more pics in "press forming" album http://picasaweb.google.com/mike.skup,

made a few attempts at pa-12/J5 style aileron nose ribs, got them as nice as piper originals(see pic), not as nice as modern Univairs(smoothness), had to retemper?? edge from a original piece of .020" 2024-T3 to a -T4? state that temporally softens it??, and form it quickly, then after rubber forming, hammer to shrink excess...

just experimenting.... still need to pour a urethane rubber pad that will fit in a metal box.... to do a true Guerin process -focus all the pressure at the die...

want to make an outer die also like "Fat Cub" shows in the jigs and fixtures thread to try.. http://www.supercub.org/forum/showt...her-neat-stuff&p=493027&viewfull=1#post493027

???? http://www.thefabricator.com/article/aluminumwelding/achieving-t6-designation-for-6061
 
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Just a thought, I know it's an entirely different process but is there some way to use hydro forming techniques to smooth out the forming process? Maybe the urethane with some heavy oil to transfer the shape and to lube the material and let it flow easier? Just a thought.
 
Lowrider said:
Just a thought, I know it's an entirely different process but is there some way to use hydro forming techniques to smooth out the forming process? Maybe the urethane with some heavy oil to transfer the shape and to lube the material and let it flow easier? Just a thought.
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thats the next fancier way that its done, with a hydraulic bladder above the rubber, more pressure/accuracy
 
So I did eventually go with carbon ribs...
All the full length and 3/4's made.
They are super strong. Have not weighed them...
All nose ribs complete.
Will start assembly in the new year when I have some space cleared...
Been busy fitting out the fuse..
wing rib 34.JPG
 

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STEEL said:
So I did eventually go with carbon ribs...
All the full length and 3/4's made.
They are super strong. Have not weighed them...
All nose ribs complete.
Will start assembly in the new year when I have some space cleared...
Been busy fitting out the fuse..
View attachment 28248
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The rib looks excellent. How has you wing project progressed?
 
Herewith some pics:
Leading edges have been dry fitted, but final fixing not yet done.
need to get the tanks in so I can finish the top straps...
2nd wing is at almost the same stage as the first one now.
 

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The wing tip is amazing. Please post more photos and details when you have time!
 
To make the Wing tip shapes, I started with MDF shapes of the ribs at the end.
Cut polysterene to the outline shape and glued them onto the MDF.
Shaped the polysterene the the leading edge shape at the front and then slowly changed the shape to match the ribs as cut.
First doing the rough removal and then sanding smooth.
Doing left and right wing tips almost at the same time to get almost perfect symmetry.
Then glass the polysterene with 6oz glass cloth and spray up to get a smooth finish.
Wrap in carbon with peel ply and vacuum bag.
Alot of work for only 1 left and 1 right wing tip, but I am happy with how they came out and prefer this look over the traditional wooden bow tips.
wing tip form 1.jpgwing tip form 2.jpgwing tip form 3.JPGwing top form 4.jpg
 

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Awesome work. What are you using to bond the ribs to the spars? I always wonder what would take the flexing without trying to delaminate. Also did you ever get a chance to weigh up the ribs?
 
STEEL said:
Herewith some pics:
Leading edges have been dry fitted, but final fixing not yet done.
need to get the tanks in so I can finish the top straps...
2nd wing is at almost the same stage as the first one now.
Click to expand...

For some reason, I can't see the pics. It says "Attached Thumbnails" but no images. I'm very interested in your composite ribs. Are you able to repost the images? A few other questions: 1) How many layers/weight CF? 2) Epoxy hand brushed, resin infusion, pre-preg? 3) Is it layed up over a male rib plug or a female mold? Thanks! Awesome work!
 
aecub said:
For some reason, I can't see the pics. It says "Attached Thumbnails" but no images. I'm very interested in your composite ribs. Are you able to repost the images? A few other questions: 1) How many layers/weight CF? 2) Epoxy hand brushed, resin infusion, pre-preg? 3) Is it layed up over a male rib plug or a female mold? Thanks! Awesome work!
Click to expand...
I used 2 layers 6oz cloth then a 3mm composite core with the cutouts and then another 2 layers of 6oz cloth.
i would wet out each layer of cloth on a piece of melamine before placing over a polished male mold.
Then peel ply, and vacuum bag all together. Got good results over all the ribs.
I have a couple left after my wing build so will weigh one and let you know what weights they came out at.
the 3mm core is the part that gives the rib the extra strength as it has some shaped cutouts etc so it’s not just flat shape.
 
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