Quadcopter

A quadcopter is the familiar X-shaped drone. Four propellers push air down; spin them faster and it climbs, slower and it drops.

To move sideways it does not have a rudder. It simply tilts by running the propellers on one side harder, so some of their push goes forwards instead of up.

The hopping drone here is built on a small off-the-shelf quadcopter with a spring leg added underneath.