Why no plywood monocoque homebuilts?

Orval Fairbairn wrote:
In article .com,
" wrote:

Morgans wrote:
"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote

The hard part would be to come up with a reasonable replacement for the
spars
in the wings. To avoid the big expensive spruce planks, one might have to
consider an engineered product like Laminated Veneer Lumber (LVL)...

Have you ever used those? They are HEAVY, with a capital "H".

SNIP


--
Jim in NC

Jenny Craig strikes again :-)

I am still very intriqued by filament winding. Spars would probably be
most obvious use of this technology. Take a look at the pictures on
this page to get an idea why.

http://www.boatdesign.net/forums/sho...11160b889f2560
2fba&t=1774&page=2

Doesn't that kindof suggest the ability to make a whole spar, wing,
fueselage or control surface in one shot? I am presuming scaled
composites uses something similar but bigger. I've seen pictures of the
system NASA uses for booster casings, they stand about 20 ft. tall if
I remember correctly.

I will be checking the local yellow pages to see if there are any
mast-makers where I live. I'd like to take a closing look at a system
like this.


-Matt

Actually, filament winding would be a poor choice for spars, as the
filaments should run primarily parallel to the spar and be concentrated
at the top and bottom. You do need some in the webs, to handle shear
loads, but an "I" section is the most efficient. A tubular spar for a
wing is also a poor choice, as it concentrates a lot of its tensile
strength at its center, where it doesn't get much loading.


Couldn't that be controlled by adjusting the weave? Perhaps weave in
three angles instead of two, with the third being parallel to the
length axis? The form could be semi-rectangular as well, which would
give you your ability to concentrate fibers on the top and bottom.
Obviously you can't escape some wastage, but "perfect" is the enemy of
"good enough".

A mast is a different story, as it is expected to take similar bending
loads in all directions; a spar does not.

Are you quite familiar with filament winding? I've got a lot of
questions if you've got the time.

-Thanks
-Matt