Extending Endurance of Multicopters: The Current State-of-the-Art

Abstract

This paper presents a detailed analysis on the viability of using alternate power methods for small multicopter Unmanned Air Vehicles (UAVs). Recently, fuel and solar cells have been successfully used to power autonomous winged UAVs for a wide range of applications, but alternate power supplies in multicopters have been much less explored due to increased power requirements compared with their winged counterparts. In this paper we discuss the theory and barriers to this technology along with ways multicopter UAV endurance can be theoretically increased by more than 50% using solar and fuel cells and how future advancements will quickly improve upon these numbers by more than 60% in the coming years.

Range, Endurance, and Optimal Speed Estimates for Multicopters

“…Only very few studies try to estimate the range, endurance or optimal flight speed by combining a multicopter aerodynamics model with a battery model [2], [8], [9], [7], [11], [10], [12]. The first group of works focuses on the hover endurance of multirotor aerial vehicles.…”

“…In [8] BEM theory is used to calculate the required power to hover and it is combined with a purely measured battery model. In [9] BEM is also employed but the focus lies on alternative power sources such as hydrogen cells. Albeit mainly focused on motor and propeller selection for UAV's, [7] presents a hover endurance estimate.…”

“…Efficiency of six different motor-propeller combinations plotted over the entire operating range of each motor. The lines represent the fitted motor model (9). Solid lines (circle marks) represent a motor-propeller combination recommended by the manufacturer, whereas the dashed lines (star marks) show mismatched pairings.…”

“…Fig. 2 exemplarily shows measured efficiencies along with the fitted models (9) for six different motor-propeller pairings.…”

“…Existing approaches for range and endurance estimates often focus on hover-endurance [8], [9], where the complex aerodynamic effects of multicopter flight can be neglected. Works concerned with estimating the maximum flight range use simplistic multicopter models for forward flight [10], [11], [12].…”