1:45 PM - 3:15 PM
[O08-P101] Aiming for One-Second Microgravity Time ! Development of Drag-Shielded Drop Experimental Apparatus
Keywords:microgravity, drag-shield, g-quality, aerodynamic drag
1. Background
1-1. Motivation
Our goal is "To enrich life in space 10 years from now," and we are conducting basic experiments that will lead to this goal. The basic experiment is a microgravity experiment in which the experimental apparatus is dropped from the third floor of the school building, utilizing the balance of gravity and inertial force during free fall. In the past experiments using cardboard boxes, it was not possible to conduct accurate microgravity experiments because of air resistance, and vibration and the inability to keep the device horizontally of the device during the fall.
In this study, "g-quality" is defined as "the perspective of evaluating the quality of a microgravity experiment, taking into account the gravity level and the vibration and horizontality of the device," and a drag-shield drop experiment device (hereinafter referred to as TGμ-DS1) was developed to improve it. The gravity level [G] is defined as [(gravity - inertial force)/gravity]. TGμ-DS1 is expected to enable microgravity experiments under high g-quality in high schools without the need for special equipment.
1-2. Originality of This Research
This research has the following features: no large-scale facilities are required, safe and high-quality experiments can be conducted repeatedly on campus, relatively inexpensive materials are used, and the experiments can be easily reproduced.
In their study of microgravity experiments in a high school (Nomura et al., 2011), an environment of 0.002±0.004 [G] was created for approximately 0.45 seconds in an indoor experiment. On the other hand, the drop tower at Nihon University can maintain an environment of 10-3[G] for about 1.1 seconds. In this study, by dropping the experimental apparatus from a height of about 10m, we aim to make the microgravity duration about 1 second.
2. Methods
When a falling object is subjected to air resistance forces, a slight acceleration remains inside the drag shield. However, TGμ-DS1 has a double structure, and the inner capsule and the experimental apparatus inside the inner capsule move independently inside the drag shield, so the experimental apparatus can maintain a near-zero gravity level without being affected by air resistance. (Table 1: Detailed description of each mechanism of TGμ-DS1) The double-layered structure of the capsule is based on the drop experiment tower at the College of Industrial Engineering, Nihon University.
The purpose of this experiment was to measure the g-quality of the fabricated experimental apparatus, and it was dropped from the third floor of the school building by approximately 10 meters. A wireless accelerometer GDX-ACC (GoDirect) was attached to the inner capsule.
3. Results
This experiment succeeded in creating an environment of -0.004[G]±0.018(sd) [G] for 0.55 s from 0.2 s after the start of the fall. 0.75 s later, a relatively large disturbance in the graph was observed, indicating a decrease in g-quality.
4. Discussion
The above results suggest that the decrease in acceleration due to the aerodynamic drag force of the inner capsule can be suppressed. Therefore, it can be said that g-quality was improved by the double-layer structure.
The decrease in g-quality at 0.75 seconds after the start of the drop is thought to be due to the contact of the inner capsule with the drag shield. This is thought to be because the drag shield's air resistance was greater than expected.
5. Conclusions
A suggestion to create a high g-quality environment (-0.004[G]±0.018(sd) for 0.55 s) was obtained by TGμ-DS1 using a double-layered capsule in a drop experiment from the third floor of a school building.
6. Future Issues
The number of experiments is not sufficient and the experimental operation needs to be smoother. In addition, there is the problem of vibration when disconnecting the holding wire from TGμ-DS1. To solve these two problems, we are planning to create a drop device.
The drag shield came into contact with the inner capsule earlier than expected, and we could not achieve the goal of microgravity duration of 1 second, which was the originality of this research. We would like to review the shape of the nose cone and upper aero parts to reduce the aerodynamic drag force received by the drag shield and extend the duration of good g-quality.
References
Osaka Prefectural Kasugaoka High School, Yusuke Nomura, Yasujiro Ota, Yuki Fujimaru. Fabrication and Improvement of a Small Microgravity Generator for Indoor Use. 2011.
Nihon University, College of Industrial Science and Engineering. Study on Fuel Droplet Evaporation in Supercritical Atmosphere Using Small Drop Tower. 2006.
1-1. Motivation
Our goal is "To enrich life in space 10 years from now," and we are conducting basic experiments that will lead to this goal. The basic experiment is a microgravity experiment in which the experimental apparatus is dropped from the third floor of the school building, utilizing the balance of gravity and inertial force during free fall. In the past experiments using cardboard boxes, it was not possible to conduct accurate microgravity experiments because of air resistance, and vibration and the inability to keep the device horizontally of the device during the fall.
In this study, "g-quality" is defined as "the perspective of evaluating the quality of a microgravity experiment, taking into account the gravity level and the vibration and horizontality of the device," and a drag-shield drop experiment device (hereinafter referred to as TGμ-DS1) was developed to improve it. The gravity level [G] is defined as [(gravity - inertial force)/gravity]. TGμ-DS1 is expected to enable microgravity experiments under high g-quality in high schools without the need for special equipment.
1-2. Originality of This Research
This research has the following features: no large-scale facilities are required, safe and high-quality experiments can be conducted repeatedly on campus, relatively inexpensive materials are used, and the experiments can be easily reproduced.
In their study of microgravity experiments in a high school (Nomura et al., 2011), an environment of 0.002±0.004 [G] was created for approximately 0.45 seconds in an indoor experiment. On the other hand, the drop tower at Nihon University can maintain an environment of 10-3[G] for about 1.1 seconds. In this study, by dropping the experimental apparatus from a height of about 10m, we aim to make the microgravity duration about 1 second.
2. Methods
When a falling object is subjected to air resistance forces, a slight acceleration remains inside the drag shield. However, TGμ-DS1 has a double structure, and the inner capsule and the experimental apparatus inside the inner capsule move independently inside the drag shield, so the experimental apparatus can maintain a near-zero gravity level without being affected by air resistance. (Table 1: Detailed description of each mechanism of TGμ-DS1) The double-layered structure of the capsule is based on the drop experiment tower at the College of Industrial Engineering, Nihon University.
The purpose of this experiment was to measure the g-quality of the fabricated experimental apparatus, and it was dropped from the third floor of the school building by approximately 10 meters. A wireless accelerometer GDX-ACC (GoDirect) was attached to the inner capsule.
3. Results
This experiment succeeded in creating an environment of -0.004[G]±0.018(sd) [G] for 0.55 s from 0.2 s after the start of the fall. 0.75 s later, a relatively large disturbance in the graph was observed, indicating a decrease in g-quality.
4. Discussion
The above results suggest that the decrease in acceleration due to the aerodynamic drag force of the inner capsule can be suppressed. Therefore, it can be said that g-quality was improved by the double-layer structure.
The decrease in g-quality at 0.75 seconds after the start of the drop is thought to be due to the contact of the inner capsule with the drag shield. This is thought to be because the drag shield's air resistance was greater than expected.
5. Conclusions
A suggestion to create a high g-quality environment (-0.004[G]±0.018(sd) for 0.55 s) was obtained by TGμ-DS1 using a double-layered capsule in a drop experiment from the third floor of a school building.
6. Future Issues
The number of experiments is not sufficient and the experimental operation needs to be smoother. In addition, there is the problem of vibration when disconnecting the holding wire from TGμ-DS1. To solve these two problems, we are planning to create a drop device.
The drag shield came into contact with the inner capsule earlier than expected, and we could not achieve the goal of microgravity duration of 1 second, which was the originality of this research. We would like to review the shape of the nose cone and upper aero parts to reduce the aerodynamic drag force received by the drag shield and extend the duration of good g-quality.
References
Osaka Prefectural Kasugaoka High School, Yusuke Nomura, Yasujiro Ota, Yuki Fujimaru. Fabrication and Improvement of a Small Microgravity Generator for Indoor Use. 2011.
Nihon University, College of Industrial Science and Engineering. Study on Fuel Droplet Evaporation in Supercritical Atmosphere Using Small Drop Tower. 2006.