Great Planes Giant Extra 330L Kit - GPMA0250 - Manual (Page 15)

Build the Fin
❏ 1. Cut the Fin plan from the plan sheet. Cover it with Great
Planes Plan Protector so the glue won’t stick to the plan.
❏ 2. Select the two 3/8" x 1-5/8" x 24" balsa sticks and
carefully choose the straightest of the 2 sticks for the fin
post. Set the second post aside for the rudder LE.
❏ 3. Cut the fin post to 18-7/8" long. Draw a centerline down
the fin post lengthwise to mark where the fin ribs will be
centered.
❏ 4. Carefully position the fin post over the plan. Using a
square, mark the top and bottom edges of each rib on the
fin post. HINT: You may temporarily pin the fin post in place
during this process.
❏ 5. Position the laser-cut 3/32" balsa vertical rib V7 so
that the rib is:
a) positioned between the lines you drew in step 6;
b) centered laterally on the fin post on the centerline you drew;
c) vertical;
d) and with the LE web notch pointing toward the model’s
left as shown in the photo. When you are confident it is
positioned properly, glue with thin CA. NOTE: Remember
that all references such as “laterally” and “model’s left”
indicate the part’s final position on the finished model and
not necessarily its current orientation.
❏ 6. Install the laser-cut vertical ribs V1-V6 as you did V7,
being careful that all tabs are pointing to the model’s left.
❏ 7. Aligning the fin post and ribs over the plan, pin the fin
post to the plan.
❏ 8. Select the 1/4" x 3/4" x 18" balsa fin LE, which will be
temporarily used as a LE jig at this time, and the die-cut
3/32" balsa fin LE web (FLE). Slip the LE jig under the tabs
on ribs V1-V7 so that the tabs are held 3/4" off the work
surface. Slide the LE web into position on all 7 ribs, being
careful that ribs V5 and V6 are properly positioned to the top
and bottom edges of the jig notch respectively. Glue the LE
web in place, being careful not to glue it to the LE jig or to
glue V5 to V6.
❏ 9. Sand the left side of the LE web to match the airfoil of
the ribs as you did on the stab LE web.
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