Indoor News and Views

Folding  F1D Wing tips

Whether you want to take along an extra wing or there is some question about your model box fitting into the overhead compartment of an airliner, here is a way to travel with a much shorter box. The wing tips are folded over so each wing will fit into a slot or box .7X8.5X15” or shorter depending on the length of the center panel. To use this system the dihedral joints are overlapped and it will be necessary to adjust the chord at those joints to comply with the 20 CM chord rule.

After the wing tips have been unfolded, the wing can be stored in one of those cardboard under the bed boxes. The box lies flat when disassembled and can easy be placed in with clothing or support gear and reassembled in a few minutes

When building the wing, overlap each tip spar at the dihedral joint (.075”) and glue it to the main spar with Aliphatic (carpenters glue) and glue the ribs in with Acetate glue. There’s no reason to worry about the film or rib coming loose near the dihedral breaks when using Aliphatic to glue the dihedral joints. After the wing is removed from the building board, make up four wire hinges using short pieces of .005 music wire bend at ninety degrees. (Four hinges weigh less than .006 g) Make a piercing tool using a .4” long piece of .005” music wire mounted in a small dowel and it’s best to sharpen the piercing end. Back up the spar with a pair of tweezers or hold the dihedral rib with your fingers. Take the tool and pierce a hole in the center of the joint and rotate the tool while pushing it through the spar, glue joint and into the dihedral rib. Insert the hinge and line up the end so that it is parallel with the spar.

.005mw hinge to prevent wing tip from separating from main spar

Wing tip in the folded position

After the wing is covered, lay out a small piece of plastic or waxed paper under each dihedral joint. Lay a small weight on the spars near the inside of each dihedral rib and one right in front of each dihedral joint and puddle two drops of water under each joint. Lift up each tip about 1/2” with a piece of balsa so that the tip outline will bow near the dihedral break. It will take several minutes for the glue to soften and it might be necessary to place a little extra water on the joints, but don’t flood them. Slowly lift the tip a little more to place added pressure to each joint. The tip outline could break at the dihedral joint if you get in a hurry. The glue will usually let go all at once and the wing tip can be folded over on the center panel. Leave the small weights in front of each dihedral joint until the aliphatic glue hardens to make sure the joint doesn’t open when the tips are folded over joint. The wire is placed at each joint to prevent this from happening but I leave them in place for added security. Place a little extra Aliphatic glue at each dihedral joint.  Reverse the procedure to fold the wing back to its original length.

L Coslick