compound curves in plywood

Earlier, BA-100 wrote:

My question is, would it be possible to laminate
your own shell using vacuum bagging? Seems to me
even the wettest veneers would split if you tried
to force them into or around a male or female mold.

Well, it's pretty easy to try it and see. Get some strips of thin
veneers (I'm thinking 1/64" to 1/32" or so) and try it out. For a test
part you can use any compound curved surface of about the curvature of
your porposed surface. I'd be inclined to try it out using VW beetle
(the old ones) fenders or roof sections from a junkyard. That'll give
you both internal and external test curve surfaces. If you can make
that work, it should give you enough experience and confidence to
proceed.

There are still folks around who know exactly how Bowlus made his
fuselage pods, it shouldn't be too hard to explore that. I believe that
Jeff Byard even has photos of the Bowlus tooling. There are also a
multitude of photos of the Lockheed Vega tools that used (I belive)
concrete molds and pressurized rubber bladders.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

"Bob Kuykendall"
egroups.com:

Earlier, BA-100 wrote:

My question is, would it be possible to laminate
your own shell using vacuum bagging? Seems to me
even the wettest veneers would split if you tried
to force them into or around a male or female mold.

Well, it's pretty easy to try it and see. Get some strips of thin
veneers (I'm thinking 1/64" to 1/32" or so) and try it out. For a test
part you can use any compound curved surface of about the curvature of
your porposed surface. I'd be inclined to try it out using VW beetle
(the old ones) fenders or roof sections from a junkyard. That'll give
you both internal and external test curve surfaces. If you can make
that work, it should give you enough experience and confidence to
proceed.

Sounds like a plan! I've located a place that sells bags for vacuum forming
that would certainly be big enough and I think Icould get an old compressor
to do the honors if I mess it around enough.

There are still folks around who know exactly how Bowlus made his
fuselage pods, it shouldn't be too hard to explore that. I believe that
Jeff Byard even has photos of the Bowlus tooling. There are also a
multitude of photos of the Lockheed Vega tools that used (I belive)
concrete molds and pressurized rubber bladders.

Thanks, and best regards to all

Yes, that's right, that's exactly how Bowlus did it. I did a lot of
research on it years ago when i started the project the first time around,
(even talked to the funder of a lot of Hawley Bowlus' creations, Steven
DuPont) but making a molded pod was pretty much out of the question at the
time. the preferable option was to do like they did with the protottypes
and pretty much every other glider of the period and make a series of
scarfed rings (why did i think this would be less work?) but when I found
out about vacuum bagging, I saw it as a possible way around this. A male
mold would be the easiest to build of course. I figure a series of ply
formers, filled in with foam and sanded to shape, then maybe a layer of
resin and voila, a half a fuselage. Has the aded advantage of being easily
replicated left and right.
If that didn't work, I suppose I could use that as a plug to make a female
mold out of concrete. (yipes, what would I do with it afterewards? ) and
use vacuum bagging on that.
Might actually give it a try...