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Dan_Thomas_nospam@yahoo.com wrote:
> shrike@cyberspace.org wrote:
> > Suprisingly I keep coming back to wood as material for mass production
> > since the whole of the structure could be made of one material. There
> > are obvious logistic benefits there, and I think most wood techniques
> > could be practically achieved robotically.
>
> Wood, especially good wood, is getting scarcer all the time.
> Consistently good wood is hard to find. It's the reason ladder
> manufacturers went to aluminum and/or fiberglass a long time ago. The
> big Sitka Spruce and other types of trees that gave us good
> aircraft-grade wood mostly went to build houses a long time ago when it
> seemed we'd never run out of the stuff. What's left is protected in
> parks.
Understood. Which is why I was interested in plywood monocoque designs.
While domestic supplies of quality timber are depleted this isn't so
everywhere. This isn't a major factor IMHO because I forsee the
markets for new aircraft forming primarily overseas. So that would
resign a new aircraft company to building its factory in perhaps China
or one of the former Soviet states, or even Africa perhaps. (When you
weren't dodging bullets, graft, malaria, etc. etc.)
> Wood also needs more care in storage; it doesn't survive well
> in moist conditions, especially warm, moist conditions, and the heat of
> an intense sun can dry it out beyond the ideal 15% moisture content and
> make if brash. Glues suffer in the heat. Wooden airplanes burn easily.
> Gluing wood in the factory is a tedious affair, requiring a lot of
> clamps, patience, and accuracy the first time. You cannot CNC-punch
> wooden sheets like you can aluminum.
Not punch, but drill/mill/saw/route/form certainly. I can imagine a
system for hot or cold pressing monocoque plywood skins that was
heavily automated. I cannot invision an equivilant system for forming
and riveting aluminum because of the floppyness of it. (technical terms
abound :-) I am thinking along the lines of a modern plywood
manufacturing plant adapted to make airplanes. I guess you could say my
approach would be to design an airplane around a factory instead of the
of the factory around the airplane.
> The companies that used to build wooden airplanes gave it up
> long ago. I think the Bellanca Viking was among the last airplane to
> use significant wood in it (in the wing). Is the Falco still in
> production? How much does it retail for?
> Aluminum and composites start to look better all the time, huh?
>
> Dan
Composites yes. Aluminum no. The reason really comes down to skilled
labor. I'd prefer the assembly to be as idiot-proof as possible,
(predicting a probable shortage of skilled labor). While composites are
not idiot proof, I suspect composites would take to automated
manufacturing better. Specifically I have been VERY interested in
filament winding as a means of making both wings and fueselages. I
have not seen this approached in any homebuilts either, though I do
understand that some hobbyists have built filament winding systems for
other things, like rocket motors for example.
Both the Falco and the Barracuda are beutious! From a hand-built
perspective their labor requirements are _huge_. But the variation of
techniques and materials is probably fairly low compared to other types
of construction. For a robot it is better to do one thing many times
than many things one time. So my hypothesis is that plywood aircraft
would benefit more from heavy automation than perhaps a Cessna or a
Maule would. The amount of data I've to support that position is
obviously lacking. But I'd be interested in other opinions on the
matter.
-Matt
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Re: Why no plywood monocoque homebuilts?
