• Advances in aircraft and spacecraft science
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• v.11 no.1
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• pp.23-31
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• 2024

This paper addresses the enhancement of long-endurance solar-powered aircraft through the integration of a rechargeable battery and Maximum Power Point Tracking (MPPT) controller. Traditional long-endurance aircraft often rely on non-renewable energy sourcessuch as batteries orjetfuel, contributing to carbon emissions. The proposed system aims to mitigate these environmental impacts by harnessing solar energy and efficiently managing its storage and utilization. The MPPT controller optimizes the power output of photovoltaic cells, enabling simultaneous charging and discharging of the battery for propulsion and servo control. A prototype is presented to illustrate the practical implementation and functionality of the proposed design, marking a promising step towards more sustainable and enduring solar-powered flight.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.523-535
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• 2012

Solar powered aircraft are becoming more and more interesting for future long endurance missions at hight altitudes, because they could provide surveillance, earth monitoring, telecommunications, etc. without any atmospheric pollution and hopefully in the near future with competitive costs compared with satellites. However, traditional aircraft sizing methods currently employed in the conceptual design phase are not immediately applicable to solar powered aircraft. Hence, energy balance and constraint analyses were performed to determine how various power system components effect the sizing of a solar powered long endurance aircraft. The primary power system components considered in this study were photovoltaic (PV) modules for power generation and regenerative fuel cells for energy storage. To verify current research results, these new sizing methods were applied to HALE aircraft and results were presented.

• Advances in aircraft and spacecraft science
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• v.8 no.1
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• pp.17-30
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• 2021

This is an investigation for a more electric regional aircraft, considering the ATR 72 aircraft as an example and the electrification of its four double slotted flaps, which were estimated to require an energy of 540 Wh for takeoff and 1780 Wh for landing, with a maximum power requirement of 35.6 kW during landing. An analysis and evaluation of three energy harvesting systems has been carried out, which led to the recommendation of a combination of a piezoelectric and a thermoelectric harvesting system providing 65% and 17%, respectively, of the required energy for the actuators of the four flaps. The remaining energy may be provided by a solar energy harvesting photovoltaic system, which was calculated to have a maximum capacity of 12.8 kWh at maximum solar irradiance. It was estimated that a supercapacitor of 232 kg could provide the energy storage and power required for the four flaps, which proved to be 59% of the required weight of a lithium iron phosphate (LFP) battery while the supercapacitor also constitutes a safer option.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.3
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• pp.35-43
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• 2017

Research for solar-powered high altitude long endurance(HALE) UAV was conducted by Korea Aerospace Research Institute(KARI), and the EAV-3 with 19.5m wing span was developed. For HALE flight, aircraft should be lightly designed. Especially, airframe structure that accounts for a large portion of the total weight of aircraft should be lightweight. In this paper, development process of airframe structure for solar-powered HALE UAV, EAV-3, is described briefly. Domestic developed T-800 grade CFRP(Carbon Fiber Reinforced Plastic) composite material with high modulus and strength was used to design main load carrying structures. Flightloads analysis that takes into account large structural deformation was carried out. Stress and flutter analyses for airframe structure sizing were conducted. Static strength test for main wing and aircraft ground vibration test were conducted successfully and structural integrity was secured.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.2
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• pp.1-9
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• 2011

Several studies on the development for solar powered uninhabited aerial vehicles(UAVs) are under way as the use of the renewable energy becomes more and more important these days. This paper is for the conceptual design by a discrete and iterative method. An initial design point with 1.5 meter wing span is determined in the global design, which deploys the mass and energy balances among each component of UAV including solar cells and airframe. Then, the iteration for subsystems is carried out with the help of Vortex Lattice Method(VLM) to optimize the aircraft configuration and the solar power system. It is demonstrated in simulations that the optimized design increases the flight time from 62 to 120 minutes when the solar power system is installed. Also, the associated dynamic analysis reveals that the designed small aircraft has the acceptable stability and controllability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.468-477
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• 2014

In this research, how a solar powered HALE (high altitude long endurance) UAV (Unmanned Aerial Vehicle) can climb and reach mission altitude, 18km, starting from the ground using only solar energy. A glider type aircraft was assumed as a baseline configuration which has wing area of $35.98m^2$ and aspect ratio of 25. Configuration parameters, lift and drag coefficients were calculated using OpenVSP and XFLR5 that are NASA open source programs, and climb flights were predicted through energy balance between available energy from solar power and energy necessary for a climb flight. Minimum time climb flight was obtained by minimizing flight velocities at each altitude and total time and total energy consumption to reach the mission altitude were predicted for different take off time. Also, aircraft moving distances due to westerly wind and flight speed were calculated.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.2
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• pp.212-217
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• 2014

Micro Aerial Vehicles (MAVs) are useful devices to assess new features that may be utilized in a full size aircraft to enhance performance or to increase endurance. In this article, sources for energy saving in the micro air vehicles are initially addressed. Then, by specifying the important parameters on energy consumption of an aircraft, a feasibility study is conducted to assess the benefit of using solar cells to increase flight endurance. Next, a new solar cell has been designed and optimized for MAVs. This cell consists of a multiple quantum wells for which the quantum factor and the absorption coefficient are calculated by solving the Shrodinger equation using MATLAB software. Then, the manner and influence of MAVs parameters using the solar cells are examined to suggest optimal planform for different purposes. In order to increase flight endurance, it is noted that by using appropriate planform and the optimized solar cells, flight endurance can be increased by more than 30 percent.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.590-600
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• 2012

In this research, generalized sizing methods were studied that can be applied to an aircraft which uses solar cell or fuel cell as energy sources. To consider multiple propulsion systems and energy resources, multiple power paths were modeled and the weight of consumable and non-consumable energy was reflected in the weight change calculation for each mission segments. In the constraint analysis, power to weight ratio was selected instead of thrust to weight ratio and used in the sizing process of balancing power and energy.

• New & Renewable Energy
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• v.7 no.3
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• pp.59-66
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• 2011

Recently, an UAV using green energy for propulsion has been developed due to exhaustion of fossil fuel. This aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, and/or batteries. Especially solar cells are installed in HALE UAV and flight tests are performed in the stratosphere. Although the solar powered UAV has the advantage of zero emission, its energy conversion efficiency is low and operation time is limited. Therefore, the solar powered UAV has been designed to operate with the secondary battery obtaining flexibility of energy management. In this study, we suggest the new operational concept of the solar powered UAV using directed-energy rayed from the surface of earth to UAV. An UAV is able to secure additional power through attaching solar cell to the lower surface of elevator. As a result, the additional energy supplied by directed-energy can improve the energy management and operational flexibility of the solar powered UAV.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.219-231
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• 2014

We develop a preliminary design optimization procedure in this paper regarding the wing planform in a solar-powered high-altitude long-endurance unmanned aerial vehicle. A high-aspect-ratio wing has been widely adopted in this type of a vehicle, due to both the high lift-to-drag ratio and lightweight design. In the preliminary design, its characteristics need to be addressed correctly, and analyzed in an appropriate manner. In this paper, we use the three-dimensional Euler equation to analyze the wing aerodynamics. We also use an advanced structural modeling approach based on a geometrically exact one-dimensional beam analysis. Regarding the structural integrity of the wing, we determine detailed configuration parameters, specifically the taper ratio and the span length. Next, we conduct a multi-objective optimization scheme based on the response surface method, using the present baseline configuration. We consider the structural integrity as one of the constraints. We reduce the wing weight by approximately 25.3 % from that in the baseline configuration, and also decrease the power required approximately 3.4 %. We confirm that the optimized wing has sufficient flutter margin and improved static longitudinal/directional stability characteristics, as compared to those of the baseline configuration.