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In article <1162062080.891895.107010@k70g2000cwa.googlegroups.com>,
"shrike@cyberspace.org" <shrike@cyberspace.org> wrote:
> Orval Fairbairn wrote:
> > In article <1162050795.167998.207430@i42g2000cwa.googlegroups.com>,
> > "shrike@cyberspace.org" <shrike@cyberspace.org> 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'm 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/showthread.php?s=93d9524a4eec4011160b889f
> > > 2560
> > > 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'm presuming scaled
> > > composites uses something similar but bigger. I have seen pictures of the
> > > system NASA uses for booster casings, they stand about 20 ft. tall if
> > > I remember correctly.
> > >
> > > I'll be checking the local yellow pages to see if there are any
> > > mast-makers where I live. I would 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 cannot escape some wastage, but "perfect" is the enemy of
> "good enough".
Filament winding wraps the material (carbon, Kevlar, glass, etc.) around
the item, whereas you want the filaments in the spar caps to run
longitudinally, because that is the direction of tensile and compressive
stresses. Filaments wrapped around the spar will carry shear stresses,
but are of little help in taking up bending loads, which comprise the
major stresses in a spar.
>
> > 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 have got a lot of
> questions if you've got the time.
I have not done any filament winding, but I'm familiar with
filament-wound rocket motor cases.
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Re: Why no plywood monocoque homebuilts?
