I wanted to have an altimeter bay in this rocket to see how high it really went. I saw this idea of having the altimeter in the nose cone and decided to go with it. The altimeter can be used as a backup ejection charge as well as the motor ejection charge. I made the unit to fit the Missile Works RRC2 because that is the altimeter I own. The compartment will be about 9 inches long and has to 3/16 bulkheads. The BT will be epoxied into the nose cone.
I cut the body tube using my tube cutting jig and cut out the pieces for the bulkhead end plates using a scroll saw. Then I sanded the two of the 4 pieces to fit just inside the BT like a bulkhead and the outer pieces were sanded to be the same outside diameter of the BT. Next I epoxied the two pieces together. I wanted the ends to have a lip so the ends could seat into the BT. Then I cut the mounting board for the altimeter to fit in the grooves I cut into the end plates. I also had to epoxy a mounting bracket for the battery, because the mounted altimeter battery was in the way of the threaded rod.
I stared on the nose cone buy cutting the hole for the altimeter bay. After finishing the bay, I test fit the bay in the hole. Since the altimeter was going to be inside most of the nose cone, I installed an external switch to turn on the altimeter while it was installed in the NC. I wired up the switch and soldered the terminals. I drilled a small hole in the top end plate and feed the wires through and sealed the hole. I then epoxied the end of the alt bay, inserted the bay into the NC and epoxied both sides of the altimeter bay into the NC. The last thing I had to do on the NC was to fill it with foam. The simulation came out to mach 1.2 on a K1100 so I needed to make the NC sturdier that it was. So I drilled a small hole and filled the NC with expanding foam. I tried the minimal expanded foam and it worked out ok. I had to clean the switch up, because I forgot to seal it as well. The nice thing about the minimal expanding foam is that it does not get very hot. This kept the heat from melting the NC and it filled the cavity very well. I let it sit for a few days to dry completely. Now the NC is finished.
Recovery
Changes I made for dual deployment:
I made the main chute out of 1.9oz rip stop nylon that I picked up at Hancock fabrics. I think I got it for $3.50 per yard, so I got three yards of green, blue and purple. I like the round chutes with spill hole because they are easy to make. I already had a spool of 1/8 inch nylon cord for the shroud lines. I needed to make a 7 foot chute and a 23 inch drogue chute. I measured and cut the material. I cut two pieces to make two halves. Then I sewed the two pieces together and put a surge stitch on the outer edge. Then I found the center and cut out the spill hole. I also put a surge stitch on the inner circle. Then I did a reinforce stitch two times to strengthen the seam lines. Once this was done, I measured and cut my shroud lines and sewed them to the chute.
I got to thinking about 8500 feet on a 7 foot parachute. Hmmm...that would take a long time to come down. It may drift for aloooonnnggg time. So I decided to go with dual deployment. I cut out a 1/2 inch bulkhead and installed two u-bolts, one on each side. Then I drilled a hole for two 6/32 T-nuts to be installed on each side. These are going to hold the ejection charge canisters. I just used two 1/2 PVC ends with a hole drilled in the middle for the screws and two small holes next to each other for the igniter wires (I use Davey fire igniter's). I also put in one of my Christmas tree sockets for the lower half to use either a socket charge or the PVC charge socket is on left. I then epoxied the bulkhead in 13 inches from the bottom after testing that I could reach in from the top and screw in the charge holder. I need to protect the wires so I epoxied two small brass tubes on the inside of the upper half to run the wires through. I also made a slight modification to the alt bay bulkhead by gluing in breakaway terminals.
