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scf627
10-20-2011, 06:05 PM
Does anyone know the recommended pattern of rib stitching that should be used on a geodetic wing structure? Our chapter has a Cygnet project with geodetic wing struture that I believe is similar to Fisher Flying Product airframes.

Thanks,
Steve

scf627
10-20-2011, 11:05 PM
I have found out that on the Fisher geodetic wings, the diagonal pieces are installed under the rib cap strips making the rib cap the highest part of the structure. This allows for normal a rib stitching pattern axially along the rib (parallel to the air flow over the wing). The Cygnet is different and it has the diagonal pieces on top. That is what creates the dilemma - does one "rib stitch" the fabric to the diagonal strips in a pattern that follows the diagonals?

Steve

Frank Giger
10-21-2011, 12:09 AM
I'd go back to what rib stitching is for in the first place for the answer: it's to supply a mechanical bond between fabric and the wing itself, as glue isn't enough.

scf627
10-22-2011, 09:29 AM
I agree with that the fabric should be rib stitched, question is what is the pattern of stitches? Does one follow the 45 degree latice work?

Steve

Frank Giger
10-22-2011, 10:32 AM
If that is where the structure fits the fabric I would. Otherwise it is going to sheer the fabric from the structure, which could be very bad.

cluttonfred
10-26-2011, 02:07 AM
If the geodetic diagonals are the high and low points in the structure then you should have a lot more potential bonding area than in a typical rib arrangement. If that is the case, then one of the methods that bond the fabric directly to the structure without rib stitching might be perfect for this application.

awsager
10-27-2011, 05:41 PM
Hi,
The Cygnet does not need to be rib stitched if you follow the procedure on the plans which calls for two thinned coats of fabric cement painted on the lattice. After shrinking fabric, MEK is rubbed through the fabric to dissolve the cement and bring it up through the weave. Ribstitching will require lots of time and the weight of the finishing tapes will be considerable. Mine first flew in 1991 and the fabric is still fast to the lattice even though it has been tied down outside since completed.
Al

scf627
10-28-2011, 09:21 AM
Yes, I realize that gluing the fabric to the diagonals without rib stitching is the technique that is suggested for this design. However, since attachement of the fabric is critical to survival, I don't want to reply only on the adhesive. I'm thinnking that adding rib stiching to the diagonals will give me the piece of mind I need.

Thanks everyone!!

Steve

chris falconar
10-28-2011, 01:16 PM
No rib stitching or taping would be necessary when using the Hipec Sun Barrier which needs only to be brushed or rollered onto polyester fabric. It soaks through and automatically adheres to the structure. After severe testing and service experience the Hipec Covering System has Canadian STC.