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WING CONSTRUCTION
Building The Wing Panels
1.
Construct four main spar assemblies by gluing the four 1/4"x1/2"x16" hardwood
spar doublers to the four 1/4"x1/2"x42" hardwood main spars. Use epoxy for this
step, and make sure the spars are kept straight while drying. Any bends or twists
built in now are there to stay!
2.
a. Pin one.of the main spar assemblies in place on the plan, being certain
that the outboard end of the spar doubler is positioned correctly.
b. The 3/32" balsa trailing edge sheeting is provided extra wide so that the
forward edge can be cut perfectly straight (use a long straightedge). Pin
the bottom T.E. sheeting in place, aligning the front edge with the plans.
c. Use three or four wing ribs to accurately position the 1/4"x1/4"x42" balsa
bottom rear spar, then pin the spar in place.
3.
a. Place a scrap of 3/32" balsa near the main spar to accurately space the
W-1 wing ribs up from the building board. (The spacing is required for the
center sheeting which will be added later.)
b. Use the dihedral gauge side of the die-cut plywood Dual Tool to set the
root W-1 wing rib at the proper dihedral angle (20),then glue it to the spars
and the trailing edge sheeting.
c. Add the remaining wing ribs (three W-1, two W-2, and six W-3) to the wing
panel.
4.
a. Use the "SHEAR WEB IDENTIFICATION" diagram on sheet two of the
plans to identify the three types of pre-cut balsa shear webs (SW-1, SW-2,
SW-3) that are used in the wing panel. The vertical wood grain is
important for maximum wing strength, but it makes the webs somewhat
fragile before installation. If one should break, simply glue it back together
and install it normally.
b. Install six SW-1 and three SW-2 shear webs as shown on the plan. Trial fit
each web before gluing, sanding the ends as necessary to make them fit
snugly between the ribs on either side. The bottom of the shear webs
should be centered on the bottom main wirig spar; the top of the shear
webs should be centered on the notch for the top main wing spar. The two
inboard rib bays do not receive shear webs because that is where the
dihedral brace will be installed later.
c. Install an SW-3shear web in each rib bay (11 total), at the front edge of the
trailing edge sheeting. These webs provide support for the sheeting and
help stiffen the wing torsionally.
NOTE: The shear webs between the W-1 wing ribs will need to be
shortened significantly to fit.
Содержание Four-Star 120
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