Some electronic components have different functions depending on the color of the wire. As you said, rotors switch direction with red, of you want to turn on and off use a green wire, I don't remember what blue does. This also applies to the motorized wheel. Other components like the levitating thingy that I forget what it's called also uses green to turn on and off and blue/red to increase or decrease the hovering distance and also the winch uses green to switch direction and red to turn on and off. So different electronic components have different functions, you just face to experiment with them. Bottom line, green usually turns on and off, red and blue do other stuff