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(PICTURES OF FIN CAN)
Odyssey:
Therion:
Therion's fin can is much heavier and sturdier than that of an L1 or small L2. Materials included:
- Phenolic motor mount tube
- Aluminum centering rings, thick enough to screw into the airframe (archived designs available in the EPDM)
- Carbon fiber airframe
- Aluminum thrust plate
- Carbon fiber/foam sandwich panel fins
The airframe of the removable fin can was slotted and drilled using a mill (see notes on fin alignment in How to: Build a Fin Can).
To assemble the fin can precisely, we followed this complicated process:
- Slide the fins into the slots in the centering rings, allowing for the appropriate spacing of the centering rings
- Slide the motor mount into the centering rings
- Slide the airframe over the fins, then screw the centering rings in place
- Remove the fins, now that the centering rings are aligned, and use a pencil with a long, thin tip to mark the edges of the centering rings on the phenolic tube
- Unscrew the centering rings and gently remove the airframe, trying not to disturb the centering rings
- Make sure the alignment marks are legible
- Mix enough Proline (an adhesive similar to epoxy) according to the package directions to attach the centering rings to the motor mount
- For each centering ring, move the centering ring out of its marked off area and cover the part of the marked off section nearest to the centering ring with a layer of Proline (plenty to stick, but not enough that it will ooze. Some will spread when you move the centering ring over the current layer).
- Move the centering ring back to its location and spin it in order to evenly coat the tube and the ring.
- Add a fillet of Proline around the centering ring, trying to avoid the sections where fin supports will be placed (a Dremel can be used to remove dried proline)
- Use a hairdryer to heat the Proline until it becomes tacky or completely hardens.
- Repeat process for next centering ring, to make sure it is still aligned. Repeat for any other centering rings.
- The fins were sandwiched between aluminum supports, which were epoxied to the centering rings. Place one or two of these between the centering rings, test with a fin, and mark their location.
- Place epoxy where the supports attach, and fillet around the supports. Repeat for next set of supports.
Once the fin can has been assembled, it is stored in four parts - the airframe, the fins, the hardware, and the motor mount. To assemble these pieces, put screws through the fin supports, threaded inserts in fins, and place a nut on the other side of the fin support. Slide the airframe over the motor mount/fin assembly. Place screws through airframe into centering rings (27 screws in total for Therion, excluding any for the rail buttons)
Improvements for ???
#weldit (CAD designs to come, pending actually making those designs)
#supasonic