A Sunflower Heat Engine

Looking for a cool science experiment to do with the kids? Why not build a type of heat engine that resembles a sunflower? [Steve] from Rimstar.org shows us how!

It’s actually a pretty ingenious little project. Using metal foil scraps from a coffee bag, [Steve] created a perfectly balanced wheel that looks kind of like a sunflower. When the foil petals come close to heat they try to expand, but much like a bimetal strip, the materials making up the packaging expand at different rates to straighten the heated petal. This moves the center of gravity of the wheel off-axis, causing a rotation. As the wheel spins, the foil petal cools off, and another one is heated, creating continual movement — at least until the heat supply is taken away!

It’s a lot of work to get the balance just right, but thanks to an ingenious axle design it’s pretty easy to make adjustments. The wheel actually floats on a nail with its point stuck to a magnet, and the other end is suspended by a series of magnets. It’s pretty much as close to a friction free axle as you can get!

For other cool engine builds, check out his simple steam engine, or his famous Corona motor he’s used in many videos!

11 thoughts on “A Sunflower Heat Engine

  1. really!!! its a science project. not a hack.
    A hack is when i open up my PC case and 5 min later it is making coffee. out of the floppy drive…
    Using a arduino of course..

    1. At first I thought I read too quickly and thought you were talking about some sort of neat, similar magnetic bearing for while the prop’s in use during flight. From looking it up though, that’s still pretty cool. http://www.instructables.com/id/Magnetic-propeller-balancer/ Though I’m surprised he didn’t have to put a notch in the magnet that the shaft is in contact with. I know HD magnets have two poles on the each face but that still surprises me, unless he just didn’t mention it.

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