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Lighter-Than-Air type stratospheric long duration platforms, now under development, are re-deployable vehicles which play identical roles as artificial satellites except that LTA platforms can be recovered, refit and launched again in case of malfunction and after their lifetime service, all of them can be recovered, unlike satellites resulting in space debris and further atmospheric contamination. These LTA stratospheric platforms can be driven by either solar power or ground-to-air transmitted microwave power. Solar powered platforms are the most environmentally friendly, but need secondary batteries for nighttime propulsion, making vehicle size bigger. This paper presents the feasibility of the solar powered stratospheric platform and its re-deployable processes.

A novel type of airships or a powered LTA aircraft has been proposed, which is designed with a rather conventionally shaped hull and with conventional thrusters and is not made as a control configured vehicle(CCV) nor utilized any sophisticated control mechanism. None of control surfaces are installed but couples of stabilizers equipped to the aft hull, and without any active control tricks the vehicle holds its stability and realizes enhanced maneuverability performances. This newly conceived type model is named as ‘ACROSTAT’. This airship can ascent and descent vertically, and can perform somersaults, spiral flights, and rotates around its C.G. as the center of the movement. The paper deals with the structural design concept of the model, design data and the attitude control principle.

To tackle global environmental problems, the acquisition of plentiful and precise data is necessary, and a means of conducting long-lasting high-resolution measurements over broad areas is required. A feasibility study has been made on a high-altitude (about 20km), super-pressured, and helium-filled PLTA (Powered Lighter-Than-Air) vehicle as an ideal platform for environmental observation. It has a long service life and carries a larger payload than an artificial satellite. This PLTA platform, named HALROP (High Altitude Long Range Observational Platform), uses a solar-powered electric propulsion system to maintain its position in space against wind currents. The solar power is acquired from solar cells. For night use, solar energy is stored in regenerative fuel cells. This study examines energy balance and provides a structural analysis of the vehicle.