Making Hollow Composite Fins for Instrumentation Tips?

Javacat1

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Hey y'all, my university's rocket team was looking at potentially integrating thermistors into composite fins for our Spaceport rocket in future years. The leading idea was to create a hollow fin shell and do something like a carbon fiber layup over the shell. The two leading thoughts for doing something like that was either 3d printing the form, or using a hexagonal phenolic material that we could slide thermistors through. Any thoughts on trying this?
 

dhbarr

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Mill half pocket, wire channel, and alignment holes in half thickness fin stock. Flip over and mill airfoil. Epoxy your thermistors and fin halves together.
 
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waltr

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Was also thinking of bonding the thermistors directly into the fin.
This would be better to get good thermal conductivity from fin surface to the thermistor.
 

Javacat1

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Was also thinking of bonding the thermistors directly into the fin.
This would be better to get good thermal conductivity from fin surface to the thermistor.
Oh yeah I forgot to mention that we would be bonding the thermistors to the fin, it's just a matter of getting them inside the fin that's the main problem
 

waltr

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Ok, if you are doing a CF layer then route channels in the core and lay in the thermistors. Then do the CF lamination to seal them in.
 

OverTheTop

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I did some fins that had a G10 isogrid core and CF skins, so essentially hollow. Technique here:
ReadyForSecondSide.JPG

Note that I tried using a 3D-printed core first, unsuccessfully, before going to a CNC routed G10 core which worked well. Velocity on the flight topped out at M2.14 successfully.
 
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