Since the picture attachment of my last posting to the forum didn't upload
I'll describe in words a way to insure exact dihedral and incidence as you
install the glider wings...or shorter, less adequate wings.
Before you cut out the BL 251 incidence template draw an extension at the
bottom of the template about an inch or so downward to capture both the
leading and trailing edges of the wing. Surround the wing with the
template board back about 2" from the leading and aft edges. The template
then partially encircles the wing securing it not only at the top but at
the bottom too. The template board will be able to support the wing.
Note exactly where the leading edge and trailing edge of the template meets
the leading and trailing edges of the actual wing. This is critical to get
the incidence exact. The curve of the template over the wing does not have
to be perfect but the spot where the template meets the wing at the
furtherst forward and aft is critical. In fact, if you have a little
accidental gap between the wing and the template you'll have a little space
into which you can push some glue to hold the incidence board securely to
the wing - eliminating a confounding variable.
Draw two ~1" squares onto the BL 251 incident template just forward and
just aft of where the leading edge and trailing edge of the template meets
the leading and trailing edge of the actual wing. When you cut out the
template include the 1" squares as part of the template board. The
template board will have a ~1" X 1"protruberance at the front and back
which will accept the threaded rods which will hold up the wings.
Drill a 1/2" hole perpendicularly down through each of the 1" square
protuberances to accept 1/2" threaded rods. Make the holes a little too
large so that the rods can slide through the holes without much friction,
but without getty sloppy. The rods need to be about 4' in length, long
enough to extend from the template to the floor of your workshop. Don't
skimp and buy 3/8" rods. Splurge and get the far more expensive 1/2" rods
because 3/8" rods allow too much wobble while you're making measurements
and wobbly rods can let the wing fall...oops!
Spot glue the templates onto each wing so the templates don't
wobble. Another confounding variable is slain before it has the chance to
bite your fine motorglider.
Insert the rods which now support the wings upwards, forward and aft.
Now you can use a 1/2" nut with a washer to raise and lower the entire wing
to set the 2.4 degrees of dihedral. You can also raise or lower the
forward or aft edge of each wing to set the 2.0 degress of incidence. You
can reset a 1/10 degree difference easily by cranking the nut up or down
each rod, pushing the wing up and down. The weight of the wing will hold
the wing against the set nut and washer on the too elevated side of the
wing. If it doesn't then use a few weights to press the wing down onto the
washer and nut.
The rods hold everything solidly in place. Spinning the nuts up and down
allow you to set and securely hold the exact 2.4 degrees of dihedral and
exactly 2.0 degrees of incidence on the glider wings.
I suppose this method would work for you short wing enthusiasts.
Remember - Glider guiders keep it up longer! ;)
Rob Neils, Ph.D.
Spokane WA USA
A162
Rob.Neils@aimcomm.com
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