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For a complete Recovery analysis, please visit the Hermes I Recovery Analysis.
Parachute Drag Coefficients
The drag coefficients of the parachutes were calculated–drogue was calculated using data between 7k and 8k meters, while main was calculated at landing. These drag coefficients are effective for the flight, they also factor in the drag on the mission package as well as interactions with the fin can.
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Main Effective CD at landing: 1.33
E-match voltage anomaly
Post flight data review notes abnormal voltage readings on Telemetrum apogee channel. Despite commanding an apogee event, the Telemetrum continued reading 4.2V across the channel for the remainder of flight. The e-match should register a significant increase in resistance within 10 mS of exceeding it's no-fire current
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of 300 mA. This suggests that the initiator misfired. A fishbone analysis was conducted to classify the nature of the issue. Evidence collection is ongoing, however it appear probable that the Telemetrum e-match is internally shorted, either autogenously or to the piston.
We checked continuity post-flight and neither e-match had continuity
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. This is not a conclusive test because the wires could have been jostled during landing or travel, however this suggests that the e-match was not internally shorted to the piston.
In the future, component level testing should include resistance checks of the e-matches before and after firing. A design revision of the firebolts should also include insulation as a design requirement.
Structures
Videography
Flight Cameras
The initial design for the Hermes avionics bay supported 4 cameras, 3 radial facing, and one downward facing. Due to integration time constraints, only two radial cameras were integrated. Due to a configuration error, the cameras took a picture when powered on. The cameras were Hawkeye Firefly Q6 cameras recording in 4K at 24 fps. It is recommended that successful video capture is considered part of a successful ground test. The cameras were also not configured with the correct time stamp. The value of the time stamp as an engineering reference should be weighed against it's 'tackiness'.
Ground Cameras
The ground cameras were laid out as shown.
| # | Camera | Note |
|---|---|---|
| 1 | GoPro Hero 4 Session | Failed to Record |
| 2 | ||
| 3 | ||
| 4 | ||
| 5 | Dayna's Cellphone | |
| 6 | Ellen's Cellphone | |
| 7 | Sam's Cellphone | Highspeed Footage. Tracked to cloud ceiling |
| N/A | Hero 5 Black | Failed to Record - heatstroke |
| N/A | Hero 6 Black | Failed to Record - card speed Low |
The high rate of failure of ground cameras suggests that we should put additional effort into our ground camera array. Doug's Rail has provided invaluable footage in the past.
Integration
Integration began at roughly 1:30 pm PST and the rocket arrived on the pad at roughly 3:00 pm PST.
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