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The last simulation before flight predicted an apogee of 31600', which proved to be very similar to the true performance of the rocket. At 2.5% error, it seems our RAS Aero model is accurate enough to predict future flights of comparable rockets. After the flight all of the data was plotted. The results are shown below. A discussion of the pre-flight vehicle descent velocity mis-estimation is in the recovery section. The University of Victoria payload altimeter cut out during vehicle descent. The cause of this failure is unknown.
Avionics
Payload
See the Hermes I Payload Analysis page
Propulsion
Thrust Curve
See the motor data page.
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Future efforts could faster-burning igniters (pyrogen or BKNO3), higher surface area propellants (pixie dust), or additional mechanical retention. While chuffing represents a minor issue on this flight, successful, rapid, and complete ignition is a necessary technical milestone for multistage flight. Care must still be taken to not over-pressurize the case or clog the nozzle with a large igniter.
Recovery
For a complete Recovery analysis, please visit the Hermes I Recovery AnalysisThe Telemetrum was configured as the primary altimeter, and the Raven was configured to fire 2 seconds after the Telemetrum for drogue, and 500 ft lower for the main. This was seen reflected in the post flight data.
Parachute Drag Coefficients
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Main Effective CD at landing: 1.33
The expected drogue Cd was .36. With a correction for the drag of the body, it was expected to be between .36 and .40. This error is probably due to a conservative body correction or a poorly characterized fabric porosity.
Knake gives hemesphericals a Cd of about 1. It seems that both the main and the drogue Cd are 33% high. It is possible that the glide ratio is .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 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.
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| # | Camera | Note |
|---|---|---|
| 1 | Hero 6 Black | Charlie's. Failed to Record - heatstroke |
| 2 | GoPro Hero 4 | Andrew R's. Good Video |
| 3 | GoPro Hero 4 Session | Charlie's. Fell Over prior to launch |
| 4 | GoPro Hero 5 Session | Maddie G's. Good Video |
| 5 | GoPro Hero5 | Sam's. Good Video |
| 6 | Dayna's Cellphone | |
| 7 | Ellen's Cellphone | |
| 8 | Sam's Cellphone | Highspeed Footage. Tracked to cloud ceiling |
| 9 | Cannon EOS T6 | Ender Kerr. Stills on Burst. Beautiful. |
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.
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