Great Planes Giant Extra 330L Kit - GPMA0250 - Manual (Page 16)

❏ 10. Position the first fin sheet flush against the fin post
and the TE of the ribs, with the lower edge overhanging rib
V1 slightly. Glue the sheet to the fin post with thin CA.
❏ 11. Gently pull the sheeting back from the ribs and apply a
bead of medium CA along each rib and along the LE web.
Roll the sheet back over the ribs and hold in place until the
CA cures.
❏ 12. Gently pull your fin off your work surface, remove the
pins, and turn it over.
❏ 13. Cut the LE web and the sheeting between ribs V5 and
V6, separating the counterbalance’s sheeting from the fin
sheeting. Cut the LE of the sheeting flush with the LE web,
being careful not to cut the tabs off the ribs.
❏ 14. From the 3/8" x 5/8" x 12" balsa stick, cut and glue the two
1-1/2" long hinge blocks in position as shown on the plan.
❏ 15. Reposition the fin flat on your work surface on its left
side with the LE again acting as a LE jig under the tabs.
Sand the LE web flush with the airfoil shape of the ribs.
Sheet the right side as you did the left, being SURE to keep
the tabs pressed firmly against the jig and the fin post sitting
flat on your work surface. Weight the sheeted fin down and
allow the CA to fully cure. NOTE: Using the jig and
weighting the fin at this critical point will ensure that your fin
is as straight as your work surface. Failure to do so may
result in a warped fin, which will negatively affect the great
flying characteristics of this model.
❏ 16. Once the CA has fully cured, trim the rib tabs off with
a razor saw. Sand the sheet and ribs flush with the LE web.
❏ 17. Trim the sheeting between ribs V5 and V6 with a razor
saw. Trim the excess sheeting off the top and bottom of the
fin and sand flush with ribs V1 and V7.
❏ 18. Center the LE laterally on the LE web, and glue it in
place. Trim the excess off the top and bottom of the fin.
Shape the LE to the airfoil shape of the fin, using the cross
section on the plan as a reference.
❏ 19. Shape the fin post to the shape of the fin. Note: Be
careful not to change the shape of the fin by sanding into
the fin sheet.
❏ 20. Cut the LE and TE between ribs V5 and V6, making
the rudder counterbalance. Sand the top of the fin and top
and bottom of the rudder counterbalance flush with ribs V5,
V6 and V7 respectively.
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