Science creates wonders that seem magical
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00:00Meet CoulombFly, the tiny rotorcraft that weighs less than a piece of paper and is powered
00:07by sunlight.
00:12Micro Aerial Vehicles could have a host of applications, from environmental monitoring
00:19to search and rescue.
00:21But these MAVs currently have a problem, endurance.
00:27At these sizes, they can usually only fly for around 10 minutes.
00:31That's because as they get smaller, factors like friction mean traditional electromagnetic
00:37motors start to lose efficiency.
00:40And while other types of propulsion have been tested, these new, lighter motors still require
00:46bulky power systems on the ground to take off.
00:50One solution could be solar power, but until now, no solar-powered MAV has been capable
00:57of untethered, sustained flight in natural sunlight.
01:02So to solve this, these researchers developed a new propulsion system, driven by a pair
01:08of ultralight high-density solar cells.
01:13The new propulsion system consists of two main components, the rotor and the stator.
01:19The stator is made up of eight pairs of alternating positive and negative electrodes arranged
01:26in a ring.
01:27Each electrode has a brush attached to it, which transfers charge to the rotor blades.
01:34When a high DC voltage is applied to the electrodes, they form electrostatic fields that drive
01:40the rotor.
01:41As it spins, the rotor's blades alternately pass each positive and negative electrode,
01:47transferring charge and maintaining the rotation.
01:51This in turn drives the propeller and lifts Coulomb Fly into the air.
01:56This design gives a greater lift-to-power efficiency than similar-sized untethered MAVs.
02:03And unlike most electromagnetic motors, it doesn't get hot, which could give these
02:09components a longer lifespan.
02:12And the researchers behind this work think that this design could lead to even smaller
02:17craft.
02:18That's why they prototyped this even tinier, tethered flyer, with a wingspan of just 8mm.
02:28Coulomb Fly isn't perfect, though.
02:31This version has no mechanism for controlling the direction of its flight, so it needs vertical
02:37rails to guide it.
02:39And its solar power source makes it susceptible to sudden changes in lighting.
02:44But the researchers are hopeful that these issues could all be solved and that a future
02:49flyer equipped with solar cells and rechargeable batteries could be lifting off at any time
02:56of day.