  We propose a novel framework for swarm-based drone delivery services with
in-flight energy recharging. The framework aims to enhance the delivery time of
multiple packages by reducing the number of stops and recharging times at
intermediate stations. The proposed framework considers various intrinsic and
extrinsic delivery constraints. We propose to use support drones whose sole
purpose is to recharge other drones in the swarm during their flight. In this
respect, we compute the optimal set of optimal support drones to minimize the
probability of delivery services and recharging time at the next stations. We
also use two settings to position the support drones in a flight formation for
comparative purposes. Two novel energy sharing methods are proposed, namely,
Priority-based and Fairness-based methods. A re-ordering method of the delivery
drones is presented to facilitate the in-flight energy composition process. An
enhanced A* algorithm is implemented to compose the optimal services in terms
of delivery time. Experimental results prove the efficiency of our proposed
approach.
