Ask an Explainer

It is possible, but not recommended. Think of a car: you can have all four wheels spaced at the four corners, or you could have them lined up in tandem. The arrangement that quadcopters (and cars) have, of four propellers spread out around the central motor, is best for balance. If you were to set them up in tandem, it would be harder to fly, and less stable. This is because you are changing the distribution of weight.