compound curves in plywood

"Ouch! 1/4 inch? All covered with resin this would be fairly heavy,
methinks. What does one canoe weigh? The fuselage would probably be roughly
double that, plus formers., hardware, ...."

A 16 foot cedar strip canoe, with seats and all the trimming is under 50
pounds. Remember the resin is not just slopped on. The strength is from
the cross grains of the fabric used. This is very light. Just enough resin
is used to cover the fabric.

A one person kayak ought to have about the same total material as the Bowlus
fuselage and it would be about 40 pounds. The inside of the fuselage could
use carbon fiber or other cloth material, which is stronger and lighter (it
is opaque, so you would not want to use that on the outside). You could
probably use Kevlar on the inside, if you thought someone might be shooting
at your Bowlus. Attachment points would add weight, but the total weight
would still be reasonable.

My cedar strip canoe gets abused regularly. I have dragged it 1/4 mile over
a gravel bar. Once, when removing it from the top of my vehicle, a gust of
wind caught it and ripped it out of my helper's hands. The canoe came
crashing down on my vehicle, leaving a large dent in the vehicle, then
crashed to the asphalt. I inspected it and found no problems. We then
launched it and went 85 miles on a week long canoe trip. I do not abuse my
aircraft like I do my canoe.

Refinishing is easy. I once bet my neighbor I could refinish my 16 foot
canoe in less than 10 minutes. I sanded for 3 minutes, whisked off with an
old t shirt, then put an old white sock over a rubber glove and dipped it in
spar varnish, covering the entire canoe in about 4 minutes. I made the 10
minutes easily and, while not perfect, it looked good from 10 feet - and
ready to get abused again. And, I got a beer from my neighbor.

Colin

I'm pretty sure that the process would be to heavy for the strength it
would provide, unless it were modified to provide several very thin
crossing layers, all of which woul have to be tightly glued to each other

I'm no expert in (or any field) but several people have mentioned about the
lack of strength a single layer plywood would have and you'd need several
layers (ad various angles) etc etc. Yet the most common new "core"
constructions uses styrofoam for a core, I'd think the plywood at almost
any thickness would be stronger. The reason for use the plywood would be for
the looks (at least that's my guess).
John

UltraJohn
thlink.net:



I'm pretty sure that the process would be to heavy for the strength
it would provide, unless it were modified to provide several very
thin crossing layers, all of which woul have to be tightly glued to
each other

I'm no expert in (or any field) but several people have mentioned
about the lack of strength a single layer plywood would have and you'd
need several layers (ad various angles) etc etc. Yet the most common
new "core" constructions uses styrofoam for a core, I'd think the
plywood at almost any thickness would be stronger. The reason for use
the plywood would be for the looks (at least that's my guess).

Well, ultimately the wood would be for looks. I could easily make a strong
fuse for this using plywood. While i was at it I could clean up the
aerodynamics and use carbon fibre for the wing spars. The added strength
would enable a longer, thinner wing and I could probably delete the struts
into the bargain! Thing is, it wouldn't be a Baby Albatross anymore. Ithink
you're confused about what is meant by single layer. A single layer
wouldn't be plywood, it'd be one layer of a sheet of plywood. It' be a ply
after layers were glued together. I can't see foam being used succesfully
as a core in this design either. Either I have to use the built up scarfed
panels method or figure a way to make a thin plywood teardrop with a farily
tight radius. Seems possible to make a three or four ply lamination using
single veneers set at angles to each other wrapping four inch or so veneer
strips over a male mold one at a time and trimming to match it's neighbor.

"COLIN LAMB"
thlink.net:

"Ouch! 1/4 inch? All covered with resin this would be fairly heavy,
methinks. What does one canoe weigh? The fuselage would probably be
roughly double that, plus formers., hardware, ...."

A 16 foot cedar strip canoe, with seats and all the trimming is under
50 pounds. Remember the resin is not just slopped on. The strength
is from the cross grains of the fabric used. This is very light.
Just enough resin is used to cover the fabric.

A one person kayak ought to have about the same total material as the
Bowlus fuselage and it would be about 40 pounds. The inside of the
fuselage could use carbon fiber or other cloth material, which is
stronger and lighter (it is opaque, so you would not want to use that
on the outside). You could probably use Kevlar on the inside, if you
thought someone might be shooting at your Bowlus. Attachment points
would add weight, but the total weight would still be reasonable.

My cedar strip canoe gets abused regularly. I have dragged it 1/4
mile over a gravel bar. Once, when removing it from the top of my
vehicle, a gust of wind caught it and ripped it out of my helper's
hands. The canoe came crashing down on my vehicle, leaving a large
dent in the vehicle, then crashed to the asphalt. I inspected it and
found no problems. We then launched it and went 85 miles on a week
long canoe trip. I do not abuse my aircraft like I do my canoe.

Refinishing is easy. I once bet my neighbor I could refinish my 16
foot canoe in less than 10 minutes. I sanded for 3 minutes, whisked
off with an old t shirt, then put an old white sock over a rubber
glove and dipped it in spar varnish, covering the entire canoe in
about 4 minutes. I made the 10 minutes easily and, while not perfect,
it looked good from 10 feet - and ready to get abused again. And, I
got a beer from my neighbor.


Hmm, i'd have to experiment with that one a bit.
It doesn't sound right to me, but I'm prepared to be amazed! God knows it's
happened to me plenty of times before...

On Mon, 11 Apr 2005 23:47:53 -0400, "Morgans"
wrote:



is not intrisically beautiful - wood is.


How about a normal composite layup with a mahogany veneer on the next
to last layer covered by fiberglas for pretty.

Ed Sullivan

How about a normal composite layup with a mahogany veneer on the next
to last layer covered by fiberglas for pretty.

Ed Sullivan


That's interesting.
I've read that most composites must be painted white to reflect heat that
could damage the foam. Do you think you could get by without the white
paint?

Earlier, LCT Paintball wrote:

That's interesting.
I've read that most composites must be painted
white to reflect heat that could damage the foam.
Do you think you could get by without the white
paint?

Well, there are resins available that will take the heat. The trouble
is that they're not commonly used in the home workshop environment.
High-temp epoxies tend to require special high-temp curing. I think
there are also vinylesters that take high temps okay, although I
understand they can be tricky to work with. They also eat styrofoam, so
you can't use them on Rutan-type construction.

And, like you say, styrofoam also has a fairly low service temperature.
But other core foams like Divynicell (rigid PVC) does come in
high-temperature formulations, and is compatible with vinylester.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com

The greatness of the Wright Brothers was that they were not limited by what
they did not know.

The Bowlus was a unique approach to flight, The design lends itself to
learning skills to make a modern replacement using either rekindled or
entirely new process.

Colin

"COLIN LAMB"
thlink.net:

The greatness of the Wright Brothers was that they were not limited by
what they did not know.

The Bowlus was a unique approach to flight, The design lends itself
to learning skills to make a modern replacement using either rekindled
or entirely new process.


True, vbut it wasn't exactly groundbreaking technology in 1938, either. A
modern replacement's been done. I want a fairly close replica.. When i
talked to Steven DuPont abou tit, he said "What do you want to build a
piece of **** like that for? I'm building an HP18! Build one of those."