Presentation Information
[O12-P44]Improvements to an Air Dome Planetarium Using Household Fans and Enhancement of Operational Efficiency
*Kyosuke Natori1, *Sojiro Tanaka1, *Syoujiro Ishikawa1, *Syuntaro Sone1, *Yosuke Suzuki1, *Koichi Takizawa1 (1. Johoku Junior & Senior High School)
Keywords:
planetarium,air dome
The “Planetarium Dome Built by High School Students Using an Air Dome System (Natori, 2024),” developed last year, had the advantage of being operable with a household fan; however, during its operation at a school festival, it faced challenges such as “screening interruptions due to insufficient strength of the entrance/exit” and “low operational efficiency.” This study aimed to verify the impact of fundamental improvements to materials and structure on durability and operational efficiency. In the previous model, agricultural mulch film was used for the dome body and the airlock (an antechamber designed to maintain air pressure differentials). However, this material was incompatible with sewing thread, leading to frequent tearing at the seams and unraveling of the thread due to the repeated stress of opening and closing. Furthermore, because there was only one air intake, it was difficult to maintain air pressure during entry and exit. Therefore, the material for the airlock section was changed from agricultural mulch film to non-woven fabric. Non-woven fabric has high compatibility with thread, allowing for the distribution of tension at the seams. Furthermore, the opening and closing mechanism for the entrance was changed from the conventional magnetic type to a zipper type to improve both airtightness and ease of operation. To increase the dome’s inflation speed and maintain air pressure, the number of intake ducts was increased from one to two, arranged in a Y-shape. The air inlets were positioned near the entrances and exits to immediately compensate for pressure drops caused by audience entry and exit. The time required for the new dome to fully inflate is approximately 8 minutes, a reduction of about 47% compared to the previous model (15 minutes). This reduced setup time and led to smoother operations. The use of non-woven fabric also helped prevent the occurrence of pinholes and cracks, which had been a concern. During the cultural festival, there was virtually no damage at the seams, and we were able to keep screening interruptions at zero. Furthermore, the combination of zippers and non-woven fabric achieved both smooth opening and closing and high airtightness. By configuring two air intakes (in a Y-shape) and placing them near the entrances and exits, the deflation of the dome during audience entry and exit was suppressed, allowing screenings to continue uninterrupted. However, regarding the extent to which this “Y-shaped” branching structure was hydrodynamically superior compared to a single thick duct, or whether airflow losses occurred, detailed comparative data has not yet been obtained, and quantitative effects have not been identified. Determining the optimal shape remains a topic for future study. As a result of these improvements, no damage occurred that would threaten operations, and the total number of visitors increased by approximately 300 from the previous year, setting a new record high. It was demonstrated that the appropriate selection of materials and the intake configuration designed with entry and exit traffic in mind dramatically enhance the practicality of air dome operations in educational settings. Reference: Takayuki Ohira. “Air Dome (INFLATABLE DOME).” megastar-net.com. (March 2025).