Heat shrink sux, big-time. It is for those who don't want to take the time to do a nice set of blades. And you guys who fit this description, don't be offended. I'm NOT criticising; just making a comment.

Anyway, it can and does lift away from the upper surface of the blade under flight loads. Your first clue is a noticeable out-of-track condition. This is due to the blade that has the stuff lifting away has lost it's efficiency. On severe cases, you hear the blades fighting each other for cyclic authority. It doesn't happen all the time; but it does happen.

Woodies covered in heat shrink are cheap, and just the ticket for someone who crashes a lot- whatever the cause of that may be. But if you want to do a more careful, efficient job without painting, Miniature AirCraft still sells their excellent blade covering. It stays down, and lasts forever. The drawback to this is that the root and tip ends of the blade are left exposed, and need to be sealed to prevent moisture migration. Three or four coats of good old clear dope do the trick here; but again, this is more trouble than a lot of folks are willing to go to.

I guess it has to do with the difference between a modeler and a hobbyist. The hobbyist just wants to play with his toy (fly it) and is not the least bit interested in tinkering, etc. The modeler enjoys the playing, but also derives as much satisfaction out of carefully crafting a nice set of woodies, or doing a killer paint job on a canopy, or tweaking his machine to be absolutely smooth, or whatever.

Steve