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edge segments, you will note a small step at the end of each rib relative to the lower surface of the
trailing edges. This step needs to be sanded away to blend the lower surface of the trailing edges
to match the undercamber of the wing. Use a small sanding block and position the wing lightly into
your hand or against a working surface (wing upside down) and carefully work the lower surface of
the T.E. stock by removing the material uniformly across the forward edge, until it is evident that the
lower wing contour is smoothly blended to match the rib contours. At the leading edge, blend the
lower surface of the leading edge segments and tip bow to blend smoothly to the profile of the ribs.
Remove all the spar standoff tabs and very lightly sand any mismatches between the lower edge of
the spar and ribs to get a flush match at all joints.
Once the wing bottom is sanded, perform similar cleanup on the upper surface. Using a flat
sanding block, lightly sand the tops of the turbulator spars to be flush with the rib contours. Finish
shaping the upper surface of the leading edge segments and bows and blend into the bottom
contour with fairly sharp radius at the nose. Carry the leading edge radius into the wing tip and
blend as required to transition from leading edge to trailing edges. Finish sanding the upper
surfaces of the trailing edge segments and tip assembly to a tapered cross section, leaving a 1/32
thick edge across the entire trailing edge of the wing.
Perform final cleanup sanding with 220 & 400 grit paper, and apply two coats of nitrate dope to all
the lower wing surface edges of the ribs, spar, and boundary members of the wing frame, and also
the upper surface boundary and dihedral break rib edges.
Cover the wing with tissue provided starting with the bottom surface, making sure to bond to each
rib and spar, tissue grain in spanwise direction. Apply one coat of non-tautening nitrate dope
thinned 50% after shrinking tissue with alcohol or water mist.
Horizontal Stabilizer Construction
Begin assembly by placing scrap balsa strips along the leading and trailing edge lines of the
stabilizer drawing to control the boundary of the leading and trailing edge segments, as done for the
wing. Assemble the S-2 ribs with doubler ribs S-2a, making a left and right hand assembly.
Position the stabilizer spar over the drawing using scrap balsa blocking to maintain position, as
done for the wing. Position leading and trailing edge segments over the plan, using the balsa strips
to position against. Use no pins through the leading and trailing edge members. Position center rib
S-1 onto the spar and best fit the spar and rib location to the drawing. Position the S-2 rib
assemblies on the drawing and spar, with the S-2a doublers facing inboard to create the bonding
edge for the S-8 closeout. Use scrap balsa blocking against the S-2 ribs to control the location of
the ribs to the drawing. Use S-8 to check the fit of this part into position against the front of S-1 and
S-2a doublers. Sand a 45 degree bevel on the lower edge to allow this part to sit flush to the
building board surface. Once satisfied with fit of these components, bond in place to the spar,
leading and trailing edge segments, and S-8 to the rib ends. Install the remaining stabilizer ribs S-
3 through S-6. Install the S-9 stiffeners to the top of the spar against the inboard side of S-6, and to
the trailing edge. This item prevents warp of the S-6 rib during covering and provides stability for
the vertical stabilizer fins attached to either end of the horizontal stabilizer.
Shape the stabilizer by blending the leading and trailing edge to airfoil contour, with a fairly sharp
leading edge radius and a trailing edge thickness of 1/32 as done for the wing. Blend the upper
edge of S-8 flush with S-1 and S-2 ribs. Sand with 220 and 400 grit sandpaper.
