RE: P51 Wing flex
I put some flat carbon fiber ribbon embedded into the bottom of the wing from tip to tip. The stuff I get is fron Dave Brown Ind. & is maybe 005" thick X ~0.75" wide and comes in a two pack ~ 3or 4' long. It's super light weight, has incredible tensile strength, and will strengthen your wing X 80 or 90%. On the mustang, I use a dremmel motor with the adjustable foot attachement which allows you to regulate the depth. Then just mark the wing and router the foam. Where the center part of the fuse is moulded into the wing, I used one of those cheepy break-off type utility blades and opened a slot through the center. Once thte carbon fiber ribbon is glued with 5min. epoxy, I used some light weight spackling, Then sanded and painted it. With brushless power, it's just a matter of time before you fold the wing. cdp182 states that a wing is only $30.00. True, but if you fold it up at 75', I guarentee you'll be buying more than a wing. An hour and a half worth of work is worth every minute. Good luck.
Rick