I bought some of these smoke producing tubes at my local fireworks shop a few 4th of July's ago. You get white smoke for a good 2 or three minutes. I bought them on July 5th, for about a buck each. I thought about trying them on an airplane, putting a PVC tube under the fuse at a small angle to hold the thing, and pointing in down at a 45 degree angle so as not to melt the covering. They get warm to touch, but I don't think they'd melt the PVC tube.