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Guinness world record for most drones airborne simultaneously.

A Do it Yourself Automotive Differential system Video found in Internet.

The automotive differential is designed to drive a pair of wheels while allowing them to rotate at different speeds. In vehicles without a differential, such as karts, both driving wheels are forced to rotate at the same speed, usually on a common axle driven by a simple chain-drive mechanism.

A Hexacopter is a rotorcraft with Six lift-generating rotors. An advantage of multirotor aircraft is the simpler rotor mechanics required for flight control.Unlike single- and double-rotor helicopters which use complex variable pitch rotors whose pitch varies as the blade rotates for flight stability and control, multirotors often use fixed-pitch blades.