Downside Up:Rethinking Parcel Position for Aerial Delivery

The conventional approach to parcel placement in most delivery drone designs today is to place the parcel centrally beneath the drone's rotor plane. However, if the parcel is too large, this will result in an obstruction of the propeller slipstream, incurring significant drag. As such, the parcel's location below the rotor plane limits the size of parcels that can be delivered, specifically super-sized parcels that protrude beyond the bounds of the four rotors. Delivering these large parcels requires bigger drone platforms, which consequently consume more energy, necessitate large storage spaces, and are less portable. In this letter, we propose an alternative approach, placing the parcel above the rotor plane. However, placing a parcel above a quadcopter encounters two main challenges. The first is the optimal position of the CG to maintain stability of the drone. Second is the aerodynamic influence on the lift of the drone with a parcel is placed above the propellers. To address these challenges, aerodynamic characterization experiments were performed and a new drone design was proposed. This letter presents a prototype quadcopter design solution that places the parcel above the propellers to enable delivery of super-sized parcels, as well as a compact rotor design configuration for lower storage cost and increased portability. The new approach of placing an over-sized parcel above propellers provides the 82% increase in thrust over putting the parcel below the propellers.