Re: painted lozenge and ribs question

Rick DeNatale (
Sat, 13 Jan 1996 09:09:19 -0500

>>Usually, the "rib tapes" were sown on to the fabric covering the ribs
>>to keep the lozenge "adheared". "Rib tapes" were also added to the
>>leading edge of the wing to "sew together" the upper and lower
>I have to disagree here. In my experience the rib tapes and glued on. On a
>wing the fabric is sewn on. The stiches provide anchors for the fabric to
>the ribs. My guess is that this also could be a plce where the fabric could
>eventually tear from the pressure of the wind. So the rib tapes are applied
>by doping them down to preven the wind from catching in the fabric and
>ripping it. Tapes are applied anywhere there is a seam, generally. There are
>some exceptions to this. The fabric for fuselages generally on the sides or
>bottom isn't taped. By it appears to me that these places used a courser
>thread and the fabric is folded over and doubled for added strength. This
>provided easy access to the interior of the fuse to allow for maintenance of
>cables etc.

I don't know about the particular aircraft in question, but this describes,
in general the practice for fabric covered aircraft, as I understand it on
the basis of what I learned at the Smithsonian Aircraft Restoration and
Preservation Seminar.

The reason that rib tapes are called rib tapes is because they are used to
cover the fabric over the ribs in the wing. Actually, the fabric is laced
to the ribs rather than sewn. The difference being the size of the cord
used. The lacing introduces holes into the fabric, and the doped on rib
tapes seal these holes against both air and water.

As for seams between fabric panels, these are sewn. They don't usually
require additional reinforcement or sealing. There are a variety of seams
used, but the most common is what is called a french seam, which is the
seam used on the outside of the legs on blue jeans. The seam looks like

. .
+--|--|-- |
| -|--|---+
. .

So there are two rows of stitching going through four layers of fabric.

>>I have not seen - nor do I know of any - planes with rib tapes
>>"stitched" between the "demarcation" of the strips of fabric - at
>>least not on the 45 degree. Chances are they were stitched on the
>>"parallel to the ribs" demarcation, only because the "demarcations"
>>sometimes (all the time?) landed on ribs.

The manual that they gave us on fabric and doping (which was a 1952 US
manual) forbids seams which fall on ribs. "Do not let seams cover a rib or
be so placed that the rib lacing will be through or over a seam." Practice
in WWI in various countries may have been different.