Quadcopters are a unique subset of flying platforms that have become very popular in the last few years. They are a flying platform that utilize the same vertical lift concept as helicopters; however, they employ not one but four motor/propeller combinations to provide an enhanced level of stability. The following is an image of such a platform:

The quadcopter has two sets of counter-rotating propellers, which simply means that two of the propellers rotate clockwise and the other two rotate counter-clockwise to provide thrust in the same direction. This provides a platform that is inherently stable. Controlling the thrust of all four motors allows you to change the pitch, roll, and yaw of the device. The following is an image that may be helpful:

As you can see, controlling the relative speeds of the four motors allows you to control the various ways in which the device can change position. To move forward, or really in any direction, we would combine a change...