Phase 2 - Second Fix Wing Joint and First Fix Stab Mounting
Second fix wing joint comes next - when handling GF always use nitrile gloves as your skin will leave traces of oil on the GF that will weaken the matrix bond:
1. cut some GF that's long enough to wrap the wing joint, put some spray mount glue onto a piece of baking paper and then stick the GF to it.
2. cut a 3/4" strip out of the baking paper/glass fiber
3. Mask off a 3/4" wide area at the wing joint and spray thinly with spray mount - just enough so the GF will stick.
4. Stick the GF/baking paper strip onto the wing joint, let the extra fall out lose at the wing's TE - then carefully peel off the baking paper to leave the GF strip on the wing.
5. Carefully smooth down the GF strip and then put the wing to one side.
6. Pick up the white pylon for the stab, and carefully push 2 pins through it at the centre of each bolt hole. These will be used for marking the drill points in the Stab.
7. Pick up the Stab for the tail and put 2 pieces of masking tape along the centre line (one on the underside, one on the top face). Mark a line on both tapes that shows the stab's centre line (use a soft tip pen!).
8. Place 'flat side' up (airfoil camber down) on the bench.
9. Now carefully align the pylon where you want to mount it on the stab - use the masking tape line and position it just in front of the CF spar in the stab.
10. Now carefully push in the pins through the Stab's skin and then all the way through and out of the other side. Then carefully pull them back out again and place another layer of tape over the pin holes on the flat side of the stab (this is to prevent epoxy 'cream' leaking out later on)
11. Flip the stab over so it is flat side down and drill (using the pin holes as reference points) for the two bolt - BUT ONLY DRILL THE SKIN ON THIS SIDE!!! DO NOT GO ALL THE WAY THROUGH THIS TIME!!
12. Use a small screwdriver, bent pins, bent bowden cable etc. to carve out the foam in a circle around each bolt hole under the skin - be careful not to puncture the skin.
13. Put to one side and now mix up some 60min epoxy - leave it to stand for a few mins to release trapped bubbles.
14. Pick up the wing again in the meantime and heat the GF joint with a hair dryer - this will thin the epoxy when it touches it.
15. Now saturate the GF wing joint with epoxy being careful to keep it off the ailerons. Once finished, remove as much epoxy as you can by wiping with a paper towel, then remove the masking tap and insert 2 pieces of folded over parcel tape into the aileron join to prevent any stray epoxy gluing them in place.
16. Use the remaining epoxy to mix up a cream with micro-balloons - again give it a few mins to release bubbles.
17. Pick up your DIY epoxy syringe (see photo on how to make with a straw) and fill the straw half way with the cream.
18. Pick up the Stab and then inject into each hard point hole with the cream, agitate it with a pin to ensure trapped air bubbles are released and leave the epoxy proud to allow for slump.
19. Once the hard points are dry, use the pin holes on the flat side as reference points and drill for the bolts.
20. Now put down the stab and pick up the wing - mark the positions for the wing bolts at 30mm and 100mm from the LE of the wing.
21. Make up the jig shown and very carfully align everything. The drill holes should be set at 90* to the flat bottom of the wing i.e perpendicular. Once you are sure, drill from below the wing with a 1mm bit to set the pilots for the two holes. Then gradually work yourself up to the 5.5mm drill bit.
20. Seal the skin edges of the holes you drilled with foam safe cyno and rotate a screwdriver in the hole until it sets. You're doing this to seal down the GF wing skin edges and prevent future cracks. If you've done everything carefully it'll all align perfectly.
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