Has a fall test been done for a 6.8 ltr 30 MPa type IV tank from a 100 mtr/300 ft height in the past? What would be the standard for hydrogen fueling tanks installation in UAVs? How many g would be a good norm for the construction of the tank cradles? 35g has been mentioned for a space craft. A very old NASA standard is available but does not provide much information on the AIAA side. For IMO guidelines, the project in question uses 5g as the norm. For storing cargo in transport cargo planes per IATA, it is 2g. As not a lot of information is available, the decision has been made to pursue an independent fall test with a 6.8 ltr cylinder with regulator, filled with hydrogen. One member of the standard committee (NEN) will assist in the process. The setup will include a 500-fps fast camera and all fragment screens will be set. Any recommendations/ideas about the setup?
ASTM might be the best point of contact for crafting this test. The ASTM F38 Committee on Unmanned Aircraft Systems is probably the best source of information on drone airworthiness criteria. They have a subcommittee developing a standard on fuel cell drone safety. One Panel member has been involved in a test with an LD vehicle tank filled with hydrogen that was dropped 60m onto a concrete pad with no issues. Fortunately, the tank impacted in the horizontal position and bounced (fortunately because if the valve had struck the concrete first, it could have become a mini rocket if the valve was damaged. It is also important to thoroughly characterize the tank and appurtenances, including the specific qualification standards/testing for the tank, regulator, etc.
Consider establishing ambient wind constraints as well, as the wind will influence the tumbling of the tank as well as the impact point. Also consider using a few blast wave transducers to record the blast pressures from some local component failure as well as the more catastrophic potential of tank rupture. The frame speed of the camera seems a little slow. Consider a higher speed camera (e.g., 3000 fps for cylinder drop/crush impact tests and 10,000 fps for bullet penetration tests; the actual speed depends on when and how the video recording will be initiated and the data storage limitations). Regarding the g values for cylinders, in automotive applications 20g has been used in the forward direction, and 8g in the other orthogonal directions per NFPA 52, which generally applies to aftermarket CNG vessels and their frames.