These new quadcopters are using a much simpler method of flying inverted: Spin the motors backwards. Quadcopters control their flight by quickly varying the speed of rotation of each motor.

A spin chirality, which is represented by an antiparallel-spin pair, is inverted not only by taking the mirror image but also by running time backward, which is not the case with spiral structure.

Vertical dancers -- those who dance high in the air many feet off the ground -- may not be able to spin a web or effortlessly ...