Hello Bud, just make sure I understand everything correctly, you say the spars
should be vertical, rather than the wings vertical which the manual seems to
suggest.
That would certainly make setting the wings up on simple sawhorses a lot
easier. Rgds, Jeroen
budyerly@msn.com wrote:
> Just my two cents.
> The spar strap prevents the spars from doing two things.
> Bending back and impacting the aileron cross connect, twisting or separating.
>
> As many have found on the original Classic, the spar cups took abuse. Some of
that due to poor security of the starboard tip by the 3/8 inch pin. Some from
the twisting of the spars under load, and some due to poor technique on
installation
and rigging.
>
> With the GW increase testing, enlarging the pin to allow a pip pin to securely
hold the spars firmly from creeping aft was a very thoughtful idea. The spar
strap really keeps the spars from bending which they do under load. Remember,
the XS short wing spar has no bid around it for a shear web, so the roves are
good in vertical bending but not so great in twisting or bowing.
>
> So belts and suspenders. Either enlarge the thickness of the spars with shear
webbing as in the glider wing, or retain them seems to be the dilemma. They
chose simple, a spar strap.
>
> I would always install a spar strap. It aids rigging if built right with some
clearance, reduces pressure on the spar cup during rigging, assists in keeping
the spars safely put under high G pullouts.
>
> Take the time and do it right. If you don't do it in construction, it may
> never
get done. In testing, if a situation requires a quick pull out, the added
spar strap fixation may become a factor. I try never to cut corners. Anything
worth doing is worth doing right.
>
> Technique:
> Support the wings and spars so the spars are exactly vertical, each wing is at
the same incidence and the spar pins rotate easily. This is important to ensure
the strap is going to be properly aligned and not just slightly askew. NEVER
clamp the spars together to get alignment.
>
> Wrap the starboard spar with blue painters tape then the release tape to give
you a few thousands more room for rigging and more importantly derigging during
construction.
>
> Make the upper curved inlet as shown but do the same on the lower on the
> starboard
side of the cup layup to ease rigging. I make my spar strap "ramp" about
1/4 inch larger than depicted as well as the strap to allow nice clean trimming.
> Make your glass wrap as shown in the manual.
> Wrap peel ply around your glass to prevent sagging and use some release tape
to hold the peel ply from sagging if necessary.
>
> In cold climates:
> Try to find a shop that may let you do the work in the warm, but if that is
> impossible:
> Make a box over the spars out of styrofoam and use an incandescent light to
> keep
it warm to cure.
>
> Once cured, if heat treat is necessary pull apart the wings and heat treat
> slowly
in the garage.
>
> The spar strap when done properly is an excellent aid in rigging as well. As
the starboard spar is inserted, it is aligned with the strap and will slide
along
the port spar and assist in self alignment. The spars stay properly vertical,
assisting the wing tip assistant. If the builder also installs a rigging
aid for the spar to slide on and assist in alignment,(keeping the spar from
sliding aft) and building a small ramp on the spar root to assist lifting the
spar as it hits the cup and thereby aligning the pins to very near their
required
elevation, even the most clumsy of assistants even without a saw horse or
trestle under the wing will be amazed how easy the rig is.
>
> Best Regards,
> Have a great holiday.. Bud Yerly
--------
Jeroen
http://www.europaowners.org/main.php?g2_itemId=44165
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