compound curves in plywood

"BA-100" wrote in message ...
"W P Dixon"
:

Luthiers commonly steam wood and form it over jigs, clamps hold it in
place until it drys out. May be the same kind of construction used to
build this sailplane. Just a thought and maybe something to check out.


Yes, I've done this in fact. Have a guitar and a violin under my belt, but
no compound curves. Most flattop guitars have a small radius which is
compound, but nothing like what I'm talking about (a complete teardrop)
This sort of technology realy died out when fibreglass hit the scene,
though i'm sure there are some masters still around.Most likely source of
info are boatbuilders, of course, but their curves wouldn't even appraoch
the radius I'm talking about.....

The key to bending wood with steam is how hot it is. Superheated steam is
best, which takes a re-heater after the water is boiled. Make sure the
plywood is made with water proof glue, which is anything of A grade or
better, or marked withEXT after the grade. It might be B grade, but I don't
remember, right off.

For testing, that type of plywood is fine, but for building a plane, use at
least marine grade, and best is aircraft grade.
--
Jim in NC

("Morgans" wrote)
For testing, that type of plywood is fine, but for building a plane, use
at least marine grade, and best is aircraft grade.


"...and best is aircraft grade"

I know about marine grade plywood, but aircraft grade?

Speaking of marine grade plywood (I paid $77 w/tax for a sheet of 3/4" last
year) is there such a thing as marine grade + green treated that they sell?
That's what I wanted, couldn't find any. Something about varnish + green
preservative doesn't do well together I was told. (???)

It was for a carpeted-over floor in a 16 ft boat. We ended up spar
varnishing our sheet a number of times.


Montblack

"Montblack" wrote in message

Speaking of marine grade plywood (I paid $77 w/tax for a sheet of 3/4"
last
year) is there such a thing as marine grade + green treated that they
sell?
That's what I wanted, couldn't find any. Something about varnish + green
preservative doesn't do well together I was told. (???)

It was for a carpeted-over floor in a 16 ft boat. We ended up spar
varnishing our sheet a number of times.


Montblack

Yea, I know what you mean.

A friend wanted to do the same thing. We found a place that treats wood,
and got him to throw in some sheets of marine grade into his treating
thingy, the next time he was running a load. We then (after waiting for it
to dry out some) put it down and put a layer of fiberglass cloth and epoxy
over it all, before laying the carpet. It looks like new, about 5 years
later.
--
Jim in NC

Montblack wrote:

Speaking of marine grade plywood

I just finished up a stitch-n-glue (4 mm plywood with single layer
fiberglass inside and out) kayak yesterday, and took it out for it's
maiden run at the local lake. It's 17' long, single seater sea kayak.
Weighs about 35 LBs, but can take an ocean entry driving out through
heavy surf, so it's not a frail structure.

While paddling around, I got to thinking about this thread, and
imagining wings either side of me, tail feathers behind...

A bright finished plywood glider would be a true thing of beauty.