DISQUS

Well done. I was wondering how a pop-pop boat would work with a tube as thin as that. It's probably a good idea to anneal any tubing used with this project, and I suspect that your brass tube might have been fairly optimal. You can find such tubing in a hobby shop; it's used by model-airplane builders. The trick of having it spin and float is simply great, and now I will have to make one. The video was well-produced; my own efforts were utter disasters, so I can appreciate yours.

The theory of operation, however, is not so straightforward. What seems to happen is that water is partially flashed into steam by the candle flame and forced out of the tube ends. Then the steam that remains in the tube below the waterline condenses, thus drawing more water up into the tube. However, there may be secondary effects that pull the water in farther than this explanation would indicate; one problem with it is that the heat from the candle is constant, but the bubbles of steam are not.

Google 'pop-pop boats' and you'll find several boats based on this principle, and there are some explanations.

M Kinsler http://www.mkinsler.com

Amorphous metals are not particularly new, nor were they developed for defense purposes. Their principal use is in the special magnetic steel used in the cores of electric power transformers. Magnetic domains are crystals, so the elimination of crystals changes the magnetic properties of the steel such that it doesn't heat up as much as its magnetic field is repeatedly reversed. While amorphous metals are undoubtedly used in other applications, I rather doubt that amorphous copper would be of great benefit in audio work. I would also want to investigate whether the crystals re-form in the wire-drawing process, which severely deforms the wire and thus necessitates annealing between successive dies.