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| Design fin can | Approx. Time Required | Number of # People Required | Notes | |
|---|---|---|---|---|
| Fin Design & Manufacturing | 36 hours | The more the merrier. | Manufacturing procedure and detailed breakdown described in "Hermes 2 Fin Design & Manufacturing" | |
Design/make jigs | ||||
| Root bond jig | Allow for tolerance so fins fit, but don't make slots too loose. Make sure you have a top plate. | |||
| Fillet jig | ||||
Tube preparation | ||||
| Sand tube | Sand inside with flapper wheel so that it fits over the motor case | |||
| Tube layup | 2-4 | Rough up the outside of the tube before layup. | ||
| Root bond | 5-minute is ok, but if you have time, use a stronger epoxy. | |||
| Root fillets | ||||
Layup preparation | ||||
| Laser-cut CF cutouts | ||||
| Spray-glue to wax paper | ||||
| Sand fillets | ||||
| Prep vacuum materials | ||||
| Layup | ||||
| Wet plies/weight | ||||
| Layup | ||||
| Put on vacuum bagging | ||||
| Vacuuming | ||||
| Oven Cure | ||||
| Set up oven/vacuum materials | ||||
| Follow epoxy cure cycle | ||||
| Remove vacuum materials | ||||
| Clean up edges | ||||
| Static load test | ||||
| Design/build jig | ||||
| Determine testing loads | ||||
| Static load test | ||||
| Analyze data | ||||
| Post-processing | ||||
| Sand fillets/outside | ||||
| Outer fillets on low spots | ||||
| Paint | ||||
| Total manufacturing time |
1. Tube Preparation
The fin can fits over the motor case (at least, it's supposed to...). Since it didn't quite fit, we sanded the phenolic tube using a flapper wheel, and then overwrapped it with 3 plies of carbon fiber. The phenolic tube acts as insulation from the heat of the motor case and is not structural, so carbon fiber needed to be added to bear the structural loads. During the tube layup, the phenolic tube was held by a pole over the layup jig (much like a pig on a spit). Have at least three people helping with the tube layup.
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