## 3 Launch Test and Results  
A launch test was conducted at 6:00 a.m. on 19 September 2021 at the former Ochiaihama in Noshiro City, Akita Prefecture, for the purpose of a flight demonstration and an attempt to break the Japanese altitude record for hybrid rockets. Figure 5 shows the state of the launch. The oxidizer filled with GSE (Ground Support Equipment) is shown in Figure 3, without the freight container, engine stand, and linear motion guide. From the visual observation by the telescope camera and the altitude data described later, it was judged that the combustion of the engine was normally complete. Altitude data from the atmospheric pressure telemetry were also successfully received. The launch was planned to be carried out on any day with good weather from 18 to 20 September 2021, including the backup date. However, due to the effects of Ty  
Figure 5: Moment of launch. a peculiar course of going from western Japan to eastern Japan after staying in the East China Sea, the launch was postponed on the 18 th as it was judged that the sea swells were high and the navigation and recovery work of the recovery ship would be difficult. On the 19 th, it was forecast that swells would remain on the sea the day before, but there was a risk that the launch on the 20 th would fail due to problems with the rocket and GSE. Therefore, a final decision was made based on the weather at 4:00 AM on the 19 th. Although the land was covered with fog, the surface of the sea could be seen from the vicinity of the launch point, and so it was decided to proceed with the launch. After inserting the rocket into the launcher, it became possible to turn on the power of the on-board camera; however, there was a problem: recording could not be started with the remote control. Condensation on the day of the flight was severe, and the video cameras on the ground also had condensation inside their camera lenses. Thus, the condensation was judged to be the cause of the problem. If the recording of the camera mounted on the rocket could not start, it would not be possible to shoot videos during flight. However, it was judged that the purpose of the experiment could be achieved even if the camera recording was not possible, so it was decided to launch the rocket. As shown in Table 4, just before launch, one of the two atmospheric pressure telemetry units and one GPS telemetry unit were out of communication. However, previous experience had indicated that the position of the antenna and the position of the receiving station could be improved depending on the attitude of the rocket, so the launch proceeded. An investigation after the flight indicated that a possible cause was that the GPS and atmospheric pressure telemetry were unable to be received before the launch because of the carrier sense function, which stops radio waves when radio waves are emitted in the same frequency band near the transmitter to avoid interference. GPS reception became impossible after the launch, but this seems to be due to restricted GPS reception for high-speed moving objects. However, there was also a problem that communication with the forced separation circuit became impossible, and it was not possible to confirm the voltage supply signal to the nichrome wire for separation or receive the separation signal. Investigations conducted after flight determined the cause to be forced separation circuit failure due to condensation or low temperatures of under 0 \({}^{\circ}\)C at high altitude. However, atmospheric pressure telemetry was received. Figure 6 shows the result of estimating the altitude from the atmospheric pressure data.