It sounds obvious, but believe it or not, a lot of people venture into a project like this with one thing in mind: "big!". This is completely the wrong approach to building a multicopter. Big is expensive, big is also less stable, and moreover, when something goes wrong, big causes more damage and is harder to repair. Ask yourself what your purpose is. Is it for photography? Videography? Fun and hobby interest? What will it carry? The example in this book is based on a standard videography drone that carries a camera between 2 and 7 pounds in weight. This covers everything from a camcorder to a small DSLR camera.
There are many configurations, but three of these rotor counts are the most common: four, six, and eight (quad, hexa, and octo-copters). The knee-jerk response of most people is again "big". It's about balancing stability and battery life. Although eight rotors do offer more stability, it also decreases flight time...
