[balloon-makers] Seams and stitches

Donald L Piccard balloon at juno.com
Sat Jan 26 17:13:08 CST 2002


My problem with tearing checks on the dotted line is financial rather
than mechanical.

When I say put load tapes on the center of the gore, I assume that you
would be putting it on a seam down the center of the gore,

On a Piccard Bulbous ("Lobular" now called "Pumpkin") there is no seam at
the gore edge,  To put a load tape there (and I can't conceive of the
likelihood of anyone doing that) would be putting it on raw fabric.   The
vertical seams between panels on the Piccard layout is in the middle of
the gore.

A note on seams:  In orthodox gas balloon fabrication using rubberized
cotton, the seam is lap seamed with rubber cement, then sewn and the
thread  and the edge of the material is taped over with rubber cemented
tape, inside and out.  The theory described in Airship Construction and
Design class at Lakehurst was that the sewing does not provide ANY
strength.  The strength of the seam is 100% in the cement.  The sewing is
only to prevent peeling.

My Mylar Pleiades balloons (Like then ones John Ninomiya used - Balloon
Life June 1997) are built using adhesive tape and a butt seam so that the
panels do not overlap.  I only used one tape on the outside of the seam
and connected all four surfaces at each connection electrically for
anti-static safety.  In the new high technology gas balloons we are now
building we use two tapes at the panel seam, one inside, one outside and
a third in the center of the gore on the inside.    This is in a Tetroon
for the extreme altitude project.

In the design of Skypower balloons I used Bostick adhesive on neoprene
coated nylon fabric with no sewing because Ed Yost had extensive
experience in using that technique on logging balloons.  Later after we
split, I made several gas balloons using high frequency sealing of
polyurethane coating on nylon fabric, again with no sewing.    It is a
welding process.   Inspection of the electronic seal is more reliable
than the multi coat adhesive seam, in my opinion.

Don Piccard,   612/333-6912
1445 East River Parkway
Minneapolis, MN 55414-3625    E-Mail:  DonPiccard at USA.Net
http://balloon.freeyellow.com/Homepage.html
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