Wrapping the nose skins around the nose ribs requires significant force in order to pull the skins down tight to the ribs. Ratchet straps distributed along the wing is the suggested method of applying this force. As each strap is tightened, the structure-to-skin alignment tends to change since the upper rib caps and main spar are not rigidly connected at this point. This condition makes it difficult to simultaneously pull the skins down tight and achieve good overall rib to skin alignment. Adding to the challenge, the nose skins are comprised of two separate aluminum sheets; an outboard section that's approximately 4 feet wide and an inboard section that's about 10 feet wide. For reference, the upper aft skins are divided into two panels also. The nose and the aft pair of inboard and outboard skins overlap at Rib 6. After much trial and error in getting the skins to pull down and align, we developed the following technique.
1) Start with wing positioned upright on table with upper aft skins (inboard and outboard) clecoed to rear ribs. Make sure the upper aft skin panels are overlapped and clecoed to Rib 6. Make sure that the existing holes (every 8 -10 spacing) along the upper aft skin spar line are marked for future reference.
2) Move two ratchet straps to the outboard nose skin and leave the inboard nose skin loose.
3) Install #40 clecos in main spar line along the inboard upper aft skin, but NOT along the outboard upper aft skin spar line. These clecos go into the previously drilled and marked positions located every 8 - 10 holes. The purpose of this step is to align the upper aft skin with the spar and hold it while the outboard panel is wrapped and drilled.
4) Ratchet down the outboard nose skin and install under the forward edge of the upper aft skin along the main spar line.
5) Drill and cleco at the pre-marked holes along the spar line for the outboard nose skin. These clecos will hold the alignment during wrapping of the inboard skin.
6) Remove the #40 clecos along the spar line of the inboard upper aft skin and ratchet down the inboard nose skin as done for the outboard section.
7) Install nose skin under upper aft skin at spar line, drill and cleco at the pre-marked holes.