• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.908-914
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• 2013

This study has developed a small solar powered UAV and performed its flight tests. In daylight, a solar powered UAV flies by using some of electricity generated from solar cells, and stores the remainder into battery. At night it flies by using electricity from battery. A solar powered UAV should have aerodynamically efficient configurations, light-weight, strong wing and fuselage. Its electric propulsion system and solar power system should also be very efficient. In the present study the solar powered UAV and its solar power system are developed for 12 hour continuous flight and the flight tests are performed to verify its performance. The flight tests performed in fall and winter to prove the present solar powered UAV is successful in four-season 12 hour flight.

• 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.

• 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.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.10-17
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• 2023

This paper describes the research and development of a 3.0 m Solar-Powered UAV system for mission flight that is based on the 4.2 m Solar-powered UAV. Both the Solar-Powered UAVs were lightened in weight by applying a composite fuselage and solar charging system. Also, a deep stall landing application and airbag module were installed for usability in mission performance. The flight performance of the Solar-Powered UAV system was verified through flight test. In particular, the 3.0 m Solar-Powered UAV performed continuous flight along the coastline of Jeju Island for 147 km in 3 hours and 50 minutes, and its performance as a mission flight was also confirmed.

• Bulletin of the Korea Photovoltaic Society
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• v.4 no.1
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• pp.5-15
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• 2018

III-V족 화합물반도체 기반의 다중접합 태양전지는 광전변환 효율이 매우 높고 내열, 내방사선 특성이 우수하여 인공위성이나 우주 탐사선의 태양광 패널에 주로 활용되어 왔다. 최근에는 III-V 태양전지의 활용범위가 지상 발전용으로 점차 확대되고 있으며, 가격 경쟁력 확보를 위한 고효율화 기술과 저가화 기술이 활발히 연구되고 있다. 본고에서는 현재 세계 최고 효율(46%)을 기록하고 있는 집광형 III-V 태양전지와 무인 항공기 및 전기 자동차의 보조 동력원으로 주목받고 있는 플렉시블 III-V 태양전지의 국내외 연구동향을 소개하고, 초고효율 III-V 태양전지의 향후 전망에 대해 논의하고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.47-58
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• 2014

In this research, the initial sizing of a HALE(High Altitude Long Endurance) UAV which uses solar power and hydrogen fuel cell as an alternative energy was performed. Instead of a wing box type, a glider type was chosen since it is relatively easy to get a data thanks to many researches abroad. Maximum takeoff weight is around 150Kg and the propulsion system is composed of motor, propeller, solar cell, and hydrogen fuel cell which can be recharged through electrolysis. Maximum takeoff weight was estimated as aspect ratio, wing span, wing area change while considering energy balance of required energy which is necessary for flight during the entire day and available energy which can be taken from the solar cell.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.401-407
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• 2016

This paper introduces 3-dimensional path planning and guidance including power model for high altitude long endurance (HALE) UAV using solar energy. Dubins curve used in this paper has advantage of being directly available to apply path planning. However, most of the path planning problems using Dubins curve are defined in a two-dimensional plan. So, we used 3-dimensional Dubins path generation algorithm which was studied by Randal W. Beard. The aircraft model which used in this paper does not have an aileron. So we designed lateral controller by using a rudder. And then, we were conducted path tracking simulations by using a nonlinear path tracking algorithm. We generate examples according to altitude conditions. From the path tracking simulation results, we confirm that the path tracking is well on the flight path. Finally, we were modeling the power system of HALE UAVs and conducting path tracking simulation during 48hours. Modeling the amount of power generated by the solar cell through the calculation of the solar energy yield. And, we show the 48hours path tracking simulation results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.479-487
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• 2022

This paper presents the control and guidance algorithm of a KAU-SPUAV(Korea Aerospace University - Solar Powered Unmanned Aerial Vehicle) which is designed and developed in Korea Aerospace University. Aerodynamic coefficients are calculated using the vortex-lattice method and applied to the aircraft's six degrees of freedom equation. In addition, the thrust and torque coefficients of the propeller are calculated using the blade element theory. An altitude controller using thrust was used for longitudinal control of KAU-SPUAV to glide efficiently when it comes across the upwind. Also describes wind estimation technic for considering wind effect during flight. Finally, introduce some guidance laws for endurance, mission and coping with strong headwinds and autonomous landing.

• 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 Association of Geographic Information Studies
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• v.18 no.1
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• pp.48-63
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• 2015

In this study, we introduce various hyperspectral data processing techniques for the monitoring of shallow and coastal waters to enlarge the application range and to improve the accuracy of the end results in Korea. Unlike land, more accurate atmospheric correction is needed in coastal region showing relatively low reflectance in visible wavelengths. Sun-glint which occurs due to a geometry of sun-sea surface-sensor is another issue for the data processing in the ocean application of hyperspectal imagery. After the preprocessing of the hyperspectral data, a semi-analytical algorithm based on a radiative transfer model and a spectral library can be used for bathymetry mapping in coastal area, type classification and status monitoring of benthos or substrate classification. In general, semi-analytical algorithms using spectral information obtained from hyperspectral imagey shows higher accuracy than an empirical method using multispectral data. The water depth and quality are constraint factors in the ocean application of optical data. Although a radiative transfer model suggests the theoretical limit of about 25m in depth for bathymetry and bottom classification, hyperspectral data have been used practically at depths of up to 10 m in shallow and coastal waters. It means we have to focus on the maximum depth of water and water quality conditions that affect the coastal applicability of hyperspectral data, and to define the spectral library of coastal waters to classify the types of benthos and substrates.