Here's the completed prototype. it has a Perfectflite Pnut in it. For the challenge, I don't need it to control ejection charges, just to measure the altitude, so the Pnut is perfect.
I had to modify my original plans and just use one screw and one weld nut. because of this, I upsized from a #4 screw to a #6 screw.
Pic 1 is the completed nose cone with the installed altimeter bay
Pic 2 is the altimeter bay removed. The weld nut was installed inside the tube. A piece of balsa was installed to provide more surface area for the threads of the nut.
Pic 3 is a picture of the inside of the tube, with balsa and weld nut installed.
Pic 4 has the Pnut installed. note that it won't be secured, but will just be floating inside the tube.
pic 5 is the plug I made for the other end of the ebay. it's a piece from a 24mm single use motor cut down with a bulkhead. It will be inserted into the tube and held in place by the nose cone that it will butt up against.
Pic 6 the forward end of the ebay with plug installed.
Pic 7. The whole electronics bay tips the scale at 11.6g. Not bad.
Now I have to drill the vent hole. I'm thinking about going through the shoulder of the rocket and the neck of the airframe since the airflow disruption is so great from the shape of the nose cone. However, if the body tube and shoulder of the rocket get misaligned, then the altimeter won't work as the vent holes will be blocked. Any thoughts/Suggestions?