Perpetual flight with a small solar-powered UAV: Flight results, performance analysis and model validation

Abstract

Abstract-This paper presents the design of the small-scale hand-launchable solar-powered AtlantikSolar UAV, summarizes flight results of a continuous 28-hour solar-powered flight that demonstrated AtlantikSolar's capability for energetically perpetual flight, and offers a model-based verification of flight performance and an outlook on the energetic margins that can be provided towards perpetual flight given today's solar-powered UAV technology. AtlantikSolar is a 5.6m-wingspan and 6.9kg mass low-altitude long-endurance UAV that was designed to provide perpetual endurance at a geographic latitude of 45N in a 4-month window centered around June 21st. A specific design emphasis is robust perpetual endurance with respect to local meteorological disturbances (e.g. clouds, winds, downdrafts). Providing the necessary energetic safety margins is a significant challenge on small-scale solar-powered UAVs. This paper thus describes the design optimizations undertaken on the AtlantikSolar UAV for maximum energetic safety margins. In addition, this paper presents the flight test results, analysis and performance verification of AtlantikSolar's first perpetual endurance continuous 28-hour flight. The flight results show a minimum state-of-charge of 40% or excess time of 7 hours during the night. In addition, the charge margin of 5.9 hours indicates sufficiently-fast battery charging during the day. Both margins exceed the performance of previously demonstrated solarpowered LALE UAVs. Another centerpiece of the paper is the verification of these flight results with the theoretical structural-, aerodynamics-and power-models that were developed and used to conceptually design the UAV. The solar-power income model is extended to take into account solar-panel temperature effects, the exact aircraft geometry and the current orientation and is compared against flight results. Finally, the paper provides an analysis and overview into under what conditions and with which energetic margins perpetual flight is possible with today's battery-and solar-cell technology. A perpetual endurance window of up to 6 months around June 21 st is predicted at northern latitudes for the AtlantikSolar UAV configuration without payload. A final outlook into first perpetual endurance applications shows that perpetual flight with miniaturized sensing payloads (small optical and infrared cameras) is possible with a perpetual flight window of 4-5 months.

Design of small hand‐launched solar‐powered UAVs: From concept study to a multi‐day world endurance record flight

“…This paper extends our previous work, which presented the initial system design and flight results of the first prototype AtlantikSolar UAV, introduced aerial sensing and mapping applications, and demonstrated AtlantikSolar 's first perpetual flight of 28‐hour duration. Sections and have been significantly extended with respect to this prior work, and Sections and are completely new contributions.…”

“…In addition, long‐endurance aerial mapping in winter conditions is described. A more recent 28‐hour continuous solar‐powered flight of AtlantikSolar AS‐2 that represented its first perpetual flight is discussed …”

Robotic technologies for solar‐powered UAVs: Fully autonomous updraft‐aware aerial sensing for multiday search‐and‐rescue missions

“…Nevertheless, overall the thermal tracking allowed 1.45 h of unpowered () flight—about 32% of the total time in which thermals were tracked autonomously. Unfortunately, these performance metrics for the active thermal tracking cannot be compared in a quantitative way against passive thermal compliance flights as, for example, the 81 h and 28 h flights. In general, the thermal updraft situation varies too significantly from day to day to draw reliable performance conclusions, and in addition both the aircraft configuration and environment for the aforementioned flights were different.…”

Optimal 3D-Trajectory Design and Resource Allocation for Solar-Powered UAV Communication Systems

“…For instance, the authors of [10] and [11] have developed solar-powered UAV prototypes and demonstrated the possibility of continuous flight for 28 hours. However, the amount of harvested solar energy depends on the flight altitude of the UAV.…”