This project aimed to take initial steps towards producing a physical representation of an ethically and legally sound drone-based system intended as a safer method to generate large cetacean related satellite telemetry, biopsy and photogrammetry data streams. Specifically we aimed to compile pertinent information to inform our design process: physical measurements (velocity, flight trajectories) for all currently employed projectiles (biopsy darts, satellite tags) from all current deployment devices by way of ballistics testing recorded using a high-speed camera with projectiles propelled horizontally.
We undertook ballistics testing at an indoor shooting range, firing biopsy darts and satellite tags (both the LIMPET and Type C implantable) at a foam target while filming their flight with a high frame rate camera, the Sony Cybershot RX100 VII set to record at 500 frames per second. The high frame rate video files were processed in the Tracker software (https://tracker.physlets.org/) and we derived both the velocity and vertical displacement of the projectiles over various distances (10 m and 15 m for biopsy darts ; 6.4 m for satellite tags,) and shot pressures (15 and 25 on the Paxarm rifle dial for biopsy darts; 10, 15 and 20 bar for LIMPETS; 8, 12 and 16 bar for Type C implantable tags). Average flight speeds ranged from 55.45 ± 1.74 ms-1 (shot distance of 10 m, Paxarm dial set at 15) to 61.77 ± 1.03 ms-1 (shot distance of 15 m, Paxarm dial set at 25) for biopsy dart flight trajectories. For LIMPET flight trajectories, average speeds ranged from 26.13 ± 0.57 ms-1 (shot distance of 6.38 m, 10 bar pressure), 32.01 ± 0.34 ms-1 (shot distance of 6.38 m, 15 bar pressure) and 38.32 ± 0.79 ms-1 (shot distance of 6.38 m, 20 bar pressure). For Type C implantable satellite tags, average speeds ranged from 21.96 ± 0.48 ms-1 (shot distance of 6.38 m, 8 bar pressure), 26.97 ± 0.58 ms-1 (shot distance of 6.38 m, 12 bar pressure) and 32.63 ± 0.41 ms-1 (shot distance of 6.38 m, 16 bar pressure).
We provide:
1. A spreadsheet (filming_metadata.xlsx) that provides details of the flight trajectory setup and recording. There are two sheets describing the recordings from the camera positioned at the firearm and the camera positioned at the target. The ‘Name’ column refers to the video file name, size is the video file size, 'DateModified' is the video file date, 'Projectile' describes the whale sampling device filmed, 'Video start time' provides the time at which the projectile was released, 'Dist to target' is the flight distance in metres, 'Dial pressure' is the deployment pressure as registered on the Paxarm dial or pressure gauge (ARTS and DanInject), 'Notebook time' for cross reference refers to the physical notes recorded, 'Replicate' is the flight trajectory replicate number, 'Notes' provides any additional information needed to interpret the data.
The videos are MP4 format and are contained in folders that indicate their date of collection in yyyymmdd (either 20210726 or 20210727) and camera position (FIREARM or TARGET). These are the videos that were processed in the Tracker software to obtain flight metrics.
The Speed-and-Trajectories.html file provides a detailed description and photos of the setup of firearms and cameras at the indoor shooting range and also plots an calculations of flight speeds and displacement for all the data points generated in Tracker for all combinations of projectile, flight distance and deployment pressure.
