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Old Nov 09, 2010, 11:15 AM
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Jack
USA, ME, Ellsworth
Joined May 2008
18,096 Posts
32" KFm3 Flat Wing Build - Part 2

32" KFm3 Flat Wing Build - Part 2

11 - Position Dowel on Tape - Hold the 1/8" dowel on the bevel and let it roll down and into contact with the tape.

12 - Put Dowel Against Bevel - As seen in the photo, the dowel should be laying on and adhering to the tape and up against the bevel on the wing panel.

13 - Attach KFm Strip to Tape - Hold the KFm 50% strip up above the tape laying back at about a 45 degree angle, center it on the wing panel, and get an even gap all the way across in front of the dowel that is about the same width as the dowel. Then lower the KFm strip down onto the tape and lay it back. It will look like the photo when the KFm strip is laid back.

Important! If the gap at the dowel is too narrow the tape will be too tight when the KFm strip is folded over and down onto the wing. The gap seen in the photo, with the KFm strip laying all the way back, is about right. It is the same as the dowel's size and even all the way across. Press down across the FFF at the bevel to get some adhesion to the tape.

14 - Check Tape Tension - To check the position of the KFm strip on the tape, lift the 50% KFm strip up until it is vertical. If you feel a very slight pulling tension on the tape as it gets to the vertical position as seen in the photo, it is right. If you feel tension before it is vertical or very much tension when it is vertical, it may be too tight and the tape may come loose or tear when the 50% KFm strip is folded all of the way down to meet the top of the 75% KFm3 strip.

If every thing is right, lay the strip back down and turn the wing panel and attached KFm strip over. Use your fingers to smooth the tape into full adhesion on the plastic skin and smooth any wrinkles. If any air bubbles are trapped they can be vented with the tip of the utility knife. Then turn the wing back to bottom side down.

15 - Mark 50% Line on 75% KFm Strip - Lay the 75% KFm strip on the wing panel and align it with the 75% line. Then make marks on both ends of the 75% strip in line with the 50% line on the wing panel. Draw a line across the 75% strip and is where the 50% strip will be trimmed for final positioning of the step. In the photo the marks had been made and the line has been drawn.

16 - Peel Plastic Skin in Support Area - The front inch of so of the 75% KFm strip is the support for the 50% strip. It also is a key part of the strength across this wing. But PU glue does not stick to the plastic skin very well so the plastic skin will be removed from the area of the 75% KFm strip where the 50% strip rests. This is important to getting a good line of glue adhesion across the wing. Take the tip of the utility knife and make the shallowest possible cut in the plastic skin along the line just drawn. You'll feel the knife tip break the skin and you don't want to go any deeper than that. Cut the line all the way across the 75% KFm strip.

Pick the corner of the plastic skin up and pull it up slowly keeping it inclined at a 45 to 60 degree angle to the foam. If you get too close to vertical, the plastic will start tearing at the pin holes. The peeling has just been started as seen in the photo.

17 - Glue 75% KFm Strip - The 75% KFm strip will be glued in place about as seen here. It wil be algned with the 75% line on the wing panel and the 50% lines on the wing panel and the 75% KFm strip will also be in line.

18 - PU Gluing Essentials - Seen are a bottle of Gorilla Quick PU (resting upside down in holder to keep it from setting up or "skinning over" in the bottle), two plastic glue spreaders cut from snap on can covers, another can cover to lay the spreaders on, and a water spritzer bottle. Spritzing with water when using PU glue is not optional, it is an important part of making sure it foams up and works well.

19 - Applying PU Glue - A typical application is seen. I run serpentine beads a distance apart and then spread the glue with a credit card like spreader. This glue is ready to be spread, when spread if you hold it to the light you should see a lightly frosted/shiny appearance where the glue is spread. Too shiny is too heavy an application (needs more spreading) and dull bare foam is not enough.

20 - Spritz, and Align Parts - Spritz water on all of the area that will be in contact with the part that has the glue spread on it, can't have too much water. PU glue is very slippery at first, make sure parts are aligned and press down with your fingers and hands to get the areas to come into contact.

To be continued...

Jack
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