Quadcopter
An innovative quadcopter capable of changing its shape in flight can squeeze through a narrow space where other drones may not fit.
Through a cable system, unmanned aircraft can adjust the arm in flight, moving it parallel to its axis to cut the width of its wings in half. After the unmanned aircraft has passed through the gap, his arm is open again and can resume normal flight.
https://www.liebertpub.com/doi/10.1089/soro.2017.0120?ref=steemhunt
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