I replaced two about a year ago. At that time I ran a small bead of black silicone around them and they have not budged since. It is enough to hold the little tabs where they need to be so it just stays.
I launched off a hill about 3 or 4 feet and I guess the duct had enough mud, tar, gravel, whatever stuck to it that it didn't flitter around and my buddy in his GTR behind me said it looked like I was doing a low altitude bombing run. That would of been priceless video!!!
I have since added aero so no more non powered flight. Well, maybe just a little here and there