) A helicopter with two pairs of rotors (vertically oriented propellers). One pair rotates clockwise; the other counter clockwise, and the flight path is controlled by the speed of each rotor. Manned quadcopters date back to the 1920s; however, consumer models appeared for aerial photography and just plain fun after the turn of the century. See personal drone
and insect drone
A Micro Quadcopter
Designed for pure entertainment, the QUARK from Rooftop Brands is charged via USB. The unit takes off vertically and flies by the speed of the rotors, which is controlled by a remote control with two AAA batteries.