Heatmobile

This is a nitinol motor. An idea I came across about 25 years ago and I haven't seen it since then. I'm very pleased to see that a German manufacturer, a man in a shed we think, is making it and it's working extremely well too. The nitinol is this little loop of wire here; it's going around two pulleys. When this bottom pulley here is immersed in very hot water, and this is kept cool, it has a tendency to start revolving. What happens is the bit of nitinol here remembers its shape which is straight, must be set for straight mode, and desperately tries to get to the straight section of the pulley, which is up here or up here depending on...it could go either way in fact. Once it's in the air though it cools down and becomes soft and pliable, which is a feature of nitinol metal, and will happily allow itself to be taken over the curved pulley at the top. So the effect is a rotating motion which goes on and on for as long as this is hot and this top bit is cold. They've rather nicely put a little propeller at the top to make it a little bit more fun when you do it. So we put it in something like a dish of Pyrex or something, and then we pour some hot water in it and it's supposed to cover it up to the first...oh just over the bottom of the first, of the bottom pulley. Then we should see some motion. [Pouring in hot water] This is near boiling water. Look at that, immediately starts going. Goodness me, isn't that superb? It's almost touching the side, not quite. So the wire's coming down to the bottom where it is heated very strongly by the hot water there; it remembers it's trying to get into a straight mode and it can only do that by carrying on round to this section of the loop where it is straight. Once it's up here though it's cooled down by the air. The air's not that warm, or not that cold here. It then becomes soft and pliable again and allows itself to be taken over the curved pulley at the top, and the cycle repeats itself. Quite extraordinary how quickly though it goes; I can't believe that the wire can gain and lose heat as quickly as it does. I think it's just superb. Silent almost too. So a lovely demonstration of the nitinol motor. And it will go both ways. If I stop it like that and then flip it this way, now it's going anti clockwise. Stop it again it will go clockwise, instantly it takes up the new motion, it doesn't matter which way it is, completely ambidextrous.