And the way it does it, is it takes its tail and it swings it one way to yaw left, and it swings its other way to yaw right.

And all of these things combine to create an enormous amount of torque on the planet.

And that four dimensional space consists of X, Y, Z and then the yaw angle.

By controlling the speeds of these four propellers, these machines can roll, pitch, yaw, and accelerate along their common orientation.

We relinquish control of yaw, but roll, pitch and acceleration can still be controlled with algorithms that exploit this new configuration.

And if we cannot figure out a way to deal with that torque, we are going to find ourselves more and more and more quickly facing situations which are simply unthinkable.

Conventional wisdom says that you need at least four fixed motor propeller pairs in order to fly, because there are four degrees of freedom to control roll, pitch, yaw and acceleration.