The blades of the fan are easily 10 meters (or a little over 10 yards) long. They make an ominous swishing sound as they slice through the air, and they’re somewhat unnerving. You can easily be killed by one (a woman was killed by this one in the mid 19th C, saving one of her children from it).
But that’s not what this is about. This is about a few radically different applications for essentially the same technology. Windmill blades are pushed by the force of the wind, and if you put several of them together around a hub, you quickly have a spinning hub. Attach that hub to a stick that’s inserted between some gears attached to a paddle wheel, and you have the wind pushing the water through the canal. Ingenious. Take that set of blades, attach it to an engine to force it to spin faster than nature would allow, and you have a fan. Attach that fan to an object, and you have locomotion. Now here’s where it gets really cool…take a couple of those fan blades, lay them out flat and attach them to your object, and you have a flying machine. The same shape that causes them to turn also causes them to provide lift. So that contrail in the sky? The jet is using (basically) the same technology as this windmill, in a variety of ways. Science is awesome.