Flying batteries: In-flight battery switching to increase multirotor flight time

TL;DR

This paper introduces a novel in-flight battery switching method for multirotors, significantly extending flight time by using a flying battery drone for mid-air power transfer without increasing size or weight.

Contribution

The paper presents a new in-flight battery swapping technique using a flying battery drone, enabling substantial flight time extension without adding significant mass.

Findings

Flight time increased by 4.7x with the method

Demonstrated repeated docking and battery switching in flight

Achieved over twice the theoretical maximum flight time for the given multirotor

Abstract

We present a novel approach to increase the flight time of a multirotor via mid-air docking and in-flight battery switching. A main quadcopter flying using a primary battery has a docking platform attached to it. A 'flying battery' - a small quadcopter carrying a secondary battery - is equipped with docking legs that can mate with the main quadcopter's platform. Connectors between the legs and the platform establish electrical contact on docking, and enable power transfer from the secondary battery to the main quadcopter. A custom-designed circuit allows arbitrary switching between the primary battery and secondary battery. We demonstrate the concept in a flight experiment involving repeated docking, battery switching, and undocking. The experiment increases the flight time of the main quadcopter by a factor of 4.7x compared to solo flight, and 2.2x a theoretical limit for that given multirotor. Importantly, this increase in flight time is not associated with a large increase in overall vehicle mass or size, leaving the main quadcopter in fundamentally the same safety class.