RE: Top Flite 1/7 P-51 Build
The method I use with Titebond is as follows.
Trim the edges of the balsa sheets with a straight edge and glue them up wide enough to cover the wing. After the glue has dried, sand both sides flat with 80 grit, then one side with 150 and 220. This will be your glassing side. Cut the skins slightly larger than needed. Trim the skins at the wing joint to fit, leaving extra overhang on the LE, TE and tip.
For the first skin, when I have access through the framing, I CA it on with thin CA.
For the second skin (closing up the wing), give an even coat of Titebond on all the ribs spars, and on the skin where it will contact the ribs and spars.
Let the glue dry for an hour before applying the skin.
Position the skin on the wing. Get your covering iron up to temp and lron the skin on. The heat will "re-activate" the Titebond glue and will give an almost instant set.
After the balsa is ironed on, trim the LE, TE and tip. Now go around the edges with thin CA. The skin is now on, sanded and nearly ready for glassing.
Scott