Making Hollow Composite Fins for Instrumentation Tips?

[Javacat1]

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]

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.

 

[waltr]

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]

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]

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]

I did some fins that had a G10 isogrid core and CF skins, so essentially hollow. Technique here:
https://forum.ausrocketry.com/viewtopic.php?f=6&t=5019&start=31

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.