Are you trying to build one of Guppy Youngren's R/Gs? There may be other plans that use it, but mentioning the use of monofilament to reinforce the leading edge of a wing - in a model rocketry context - reminded me of that plan.

http://georgesrockets.com/GRP/GLIDE...IT-Scans223.jpg

If you examine plans from those days, they seemed to favor replacing the leading edge of the wing with strip of hard balsa or spruce. I think this wasn't done to just toughen up the leading edge of the wing. It would make sanding a nicely shaped leading edge into the wing easier.

The monofilament might have been experimenting with a turbulator on a low drag airfoil. I can't imagine a thin little line of monofilament "reinforcing" anything. It certainly worked - he set a world and national record with that wing.

__________________
-Wolfram v. Kiparski
NAR 28643 - TRA 15520
MTMA Section #606 President