Standard 4-engine copter is VERY simple hardware wise - 4x blades+engines attached directly to a frame, plus some orientation sensors stolen from a phone. And t

Standard 4-engine copter is VERY simple hardware wise - 4x blades+engines attached directly to a frame, plus some orientation sensors stolen from a phone. And that's enough to maneuver in any direction with ease, with turning radius of zero. That's why the whole industry is booming