By David Shaw, 28 April 2021
NASA’s Ingenuity helicopter has made history by flying on Mars. To celebrate the first flight of a copter on another planet, here’s a simple unpowered helicopter you can build at home!
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By Carol Saab, 4 July 2013
What happens when you spin a coin on a table? It spins and rolls (or ‘spolls’), for starters. How it stops is much more fascinating.
