• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.285-288
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• 2005

A Stratospheric airship should stay long to achieve its original mission. Meanwhile, to obtain what the solar radiation and heat transfer have an effect on Stratospheric condition, heat analysis has been done. For this work, Stratospheric heat condition's been examined and for the numerical analysis, by using Gridgen, grids of airship have been generated. And by using STAR-CD, the study about heat characteristic of airship model was carried out. Especially, with changing the position of the Sun, the temperature change of the airship body was focused on. With this background, the possibility of realizing the simulation of the effects solar radiation have on the Stratospheric airship.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.89-96
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• 2005

This study has been performed on the mechanism of heat transfer between stratospheric airship and its surroundings while the airship is staying in the air at the altitude of 20km. The computational grid of airship has been generated and the results influenced by the number and the shape of grids have been compared. The temperature distributions have been obtained through this thermal analysis considering three modes of heat transfer - conduction, convection and radiation - in stratospheric conditions. Based on the airship's surface and inner temperature variations, the influence of temperature distributions on the helium envelope and the payload has been predicted.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.252-255
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• 2005

The effort to realize the concept of stratospheric airship, which can fly at about 20km altitude, has been persevered since late 1980's. Referring to the feasibility study of ensuring the flight duration of the airship over 1year, total weight is about 30 tons, the length is about 200m. There are lots of key technologies to be solved to develop the system, and one of the essential prerequisite technologies is regenerative fuel cell system. In this paper, design requirement of regenerative fuel cell system is introduced with the feasibility study results of the challenging stratospheric airship.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.432-441
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• 2016

Solar energy is the ideal power choice for long-endurance stratospheric airships. The output performance of solar array on stratospheric airship is affected by several major factors: flying latitude, flight date, airship's attitude and the temperature of solar cell, but the research on the effect of these factors on output performance is rare. This paper establishes a new simplified analytical model with thermal effects to analyze the output performance of the solar array. This model consisting of the geometric model of stratospheric airship, solar radiation model and incident solar radiation model is developed using MATLAB computer program. Based on this model, the effects of the major factors on the output performance of the solar array are investigated expediently and easily. In the course of the research, the output power of solar array is calculated for five airship's latitudes of $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$ and $60^{\circ}$, four special dates and different attitudes of five pitch angles and four yaw angles. The effect of these factors on output performance is discussed in detail. The results are helpful for solving the energy problem of the long endurance airship and planning the airline.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.31-38
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• 2006

A study of thermal characteristics of the airship considering radiation heat transfer has been conducted by building a numerical model for the airship in order to identify the possibility to obtain the reliable flight performance in severe stratospheric heat conditions. The variations of distributed temperature of the skin and the inner flow by free convection have been calculated according to the change of the solar position. As the results of the analyses, the stratospheric heat conditions slightly have an influence on the flight performance of the airship.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.485-492
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• 2015

Small advance ratio and low Reynolds number of stratospheric propulsion system bring lots of challenges to the design of propellers. Contra-rotating propeller configuration is proposed to improve the propulsion efficiency. In this paper, the feasibility of contra-rotating propeller for stratospheric airship has been assessed and its performance has been investigated by wind tunnel tests. The experimental results indicate, at relatively low Reynolds number, although the advance ratio is fixed, the performance of propellers is different with variation of Reynolds number. Moreover, at the same Reynolds number, the efficiency of contra-rotating propeller achieved appears to be a few percent greater than that for a standard conventional propulsion system. It can be concluded that contra-rotating propellers would be an efficient means to improve the performance of stratospheric airship propulsion system.

• ETRI Journal
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• v.22 no.1
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• pp.12-19
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• 2000

Wireless communication systems using airship have been proposed in worldwide. The airship will be located at the stratosphere about $20{\sim}23\;km$ above the sea level. The position of airship will vary within the station keeping range with time due to the drag of the wind in the stratosphere. When the earth station antenna has a high gain without the tracking function, the antenna performance may be degraded by a small variation of the airship. This means that variation of airship location could result in serious degradation of the system performance. In this paper, degradation in earth station's Equivalent Isotropic Radiated Power (EIRP) and Gain to noise Temperature ratio (G/T) due to the stratospheric platform movements has been derived by calculating the deviation angle of the main beam directions between the earth station and the platform antenna. In this case, the antenna of the earth station has been assumed circular and/or patch array antennas.

• Advanced Composite Materials
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• v.17 no.4
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• pp.319-332
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• 2008

The thermoelastic behaviors of an inflatable fabric membrane structure for use in a stratospheric airship envelope are experimentally and numerically investigated. Mechanical tensile properties of the membrane material at room, high, and low temperatures are measured using an $Instron^{(R)}$ universal testing machine and an $Instron^{(R)}$ thermal chamber. To characterize the nonlinear behavior of the inflated membrane structure due to wrinkling, the bending behavior of an inflated cylindrical boom made of a fabric membrane is observed at various pressure levels. Moreover, the envelope of a stratospheric airship is numerically modeled based on the thermoelastic properties of the fabric membrane obtained from experimental data, and the wrinkled deformed shape induced by a thermal load is analyzed.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.805-808
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• 1999

The researches about the stratospheric communication system are on process in USA, Japan, Europe and etc. The Airship is expected to be fixed at its position in stratosphere but perhaps its position is changed slightly because of wind in stratosphere. If earth station antenna has high gain without tracking function, even though the airship location has a little variation, degradation of antenna gain is occurred because of narrow beamwidth. In this paper, EIRP and G/T variation of the ground system due to the position variation of airship are examined.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.2
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• pp.82-94
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• 2001

The purpose of this paper is to analyze the static and dynamic stability-of the unmanned airship under development ; the target airship's over-all length of hull is 50m and the maximum diameter is 12.5m. For the analysis, the dynamic model of an airship was defined and both the nonlinear and linear dynamic equations of motion were derived. Two different configuration models (KA002Y and KA003Y) of the airship were used for the target model of the static stability analysis and the dynamic stability analysis. From the result of analyses, though the airship is unstable in static stability, dynamic characteristics of the airship can provide the stable dynamic stability. All of the results, airship models and dynamic flight equations will be an important basement and basic information for the next step of developing the automatic flight control system(AFCS) and the stability augmentation system(SAS) for the unmanned airship as well as for the stratospheric airship in the future.