Foaming in a nose cone bay into a plastic nose cone?

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Not Quite Nominal

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I like nose cone bays. They're good for trackers, might as well use that space for something, and good for CG reasons. For HPR, I've got a couple of MAC phenolic bays. Great stuff.

The problem with nose cone bays in plastic nose cones is that nothing sticks to plastic, thus the MAC-style clamped shoulder bay. I think that approach requires a sturdy HPR nose cone though. I've got a BT80 cone that I'd like to put a tracker into.

I started thinking about two part foam, which sticks to absolutely everything and can be used to foam weight into nose cones.

So:
  1. Make a bay out of a 38mm body tube and a bulkhead
  2. Cut a 38mm-sized hole in the base of the nose cone
  3. Drill another hole for foam pouring
  4. Insert and carefully align bay in NC hole
  5. Pour foam / spray Great Stuff into the hole.
Even if the two part foam doesn't stick that well to the plastic nose cone, if it sticks well to the body tube the tube won't be able to come out

Thoughts?
 
Great Stuff is not good for enclosed spaces as it will not fully cure without air. Instead install your nosecone bay using 2 part foam ( Sika Post Fix from Lowes will work fine). First install the bay and centering ring, drill hole in CR to inject foam through (make sure and calculate how much foam is needed). I used Sika Post Fix to mount a 98mm AV bay and removable nose weight tube into a 7.5" Pinnacle or Loc nose cone. Your method posted should work with proper foam.

Here is my how I work with Sika Post Fix: https://www.rocketryforum.com/threads/sika-post-mix-expanding-foam.150303/
 
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Here is an Apogee Katana nose cone with electronics bay. The nose cone is blow molded and kinda wimpy for a high-power rocket, so I thought foaming the thing was a good idea. Overall, it came out a bit hefty, but that is OK.

I cut off the entire bottom/sloped part of the cone shoulder. The bay is a length of drain pipe adapter with a screw cap fitting. I used PML 2-part foam to bond it into the cone along with a length of kevlar as a harness attachment. I then added a centering ring to add final stiffness to the perimeter of the shoulder. The 3 holes drilled through the centering ring and foam are to allow the shear pins to shake out.

20200118_153214.jpg 20200118_153124.jpg 20200118_153008.jpg
 
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