Solar-Powered Unmanned Aerial Vehicles on Mars: Perpetual Endurance
- Paper number
IAC-07-A5.I.-A3.I.B.01
- Author
Mr. Andrew Klesh, University of Michigan, United States
- Coauthor
Dr. Pierre Kabamba, University of Michigan, United States
- Year
2007
- Abstract
Inspired by the Vision for Space Exploration and motivated by long-endurance mission requirements, this paper considers the preliminary design of Mars-based, solar-powered unmanned aerial vehicles (UAVs). These UAVs are equipped with solar cells on the upper surface of the wings, which collect energy for propulsion. On Mars, such UAVs can provide exploration and communication platforms unmatched by today's rovers. Both of these missions are enhanced by perpetual endurance flight. We define perpetual endurance as the ability of the UAV to collect more energy from the Sun than it dissipates in flying, over the duration of a solar day. Several previous studies have examined preliminary design for solar-powered UAVs and considered the minimum power requirement for maneuvers. However, an integrated design process must consider the environment, mission and payload of an aircraft together, in order to specify geometry and assess performance. This is what the current paper does - specifically, this paper quantifies the requirement for perpetual endurance in solar-powered flight. The endurance of a solar-powered aircraft is determined by the Power Ratio, a non-dimensional number that can be computed before flight, and that represents the ratio of power collected by the solar cells to power spent overcoming drag. The Power Ratio of an aircraft depends explicitly on environmental factors, such as atmospheric density, and geometric factors, such as wing span. This paper shows the existence of a threshold value of the Power Ratio - the Perpetuity Threshold - such that, in order to achieve perpetual endurance, the Power Ratio must exceed the Perpetuity Threshold. This Perpetuity Threshold depends explicitly on environmental factors such as the relative duration of day and night. As an example, consider the Gossamer Penguin, with a payload of 30 kg, taking into account necessary equipment. Assume this glider is outfitted with solar cells for solar-powered flight. Also assume that on Mars, the solar day provides 13.5 hours of sunlight and 11 hours of darkness. Then, the Perpetuity Threshold of the glider is evaluated as 1.81, whereas its Power Ratio is 1.70. Hence, such a UAV is incapable of perpetual endurance on Mars. This example illustrates how the Perpetuity Threshold of Power Ratio must be considered in aircraft design and mission planning. The conference version of this paper will present preliminary design examples that meet the Perpetuity Threshold for solar-powered flight on Mars and discuss the implications of this threshold on the geometry of the aircraft.
- Abstract document
- Manuscript document
IAC-07-A5.I.-A3.I.B.01.pdf (🔒 authorized access only).
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