Conceptual Sizing of Vertical Lift Package Delivery Platforms

Abstract

Conceptual sizing and performance estimation of four vertical takeoff and landing (VTOL) configurations for a package delivery mission is presented in this Paper. The multifidelity VTOL design framework HYDRA is used to size a notional quadrotor, hexarotor, quadrotor biplane tailsitter (QBiT), and a lift-augmented tricopter for weight classes of 10, 15, 20, and 25 kg. Sizing is performed using a combination of physics-based empty weight models for the airframe, rotor blades, and wings, along with statistical models for predicting motor and battery weights. A gradient-based optimization methodology was implemented to identify the best designs for each configuration under each weight class. An optimization-based longitudinal trim methodology was used to identify the appropriate shaft power settings for each vehicle at various trimmed flight conditions along the mission profile. Representative payload delivery and return scenarios were constructed from different cruise speeds and ranges to identity a vehicle design in each configuration that can complete the highest number of payload drop missions successfully. The hexarotor performed better than the quadrotor in terms of requiring lower installed power and deliver heavier payload packages for a given radius of action. Wing-borne designs such as the QBiT and tricopter are capable of delivering packages in a short time owing to full/partial conversion to airplane mode during cruise flight but may require careful fine-tuning of the trimline and flight control system to successfully transition between hover and cruise flight modes.