West Coast Rocketry - Screamer
Contributed by John Lee Brief: The Screamer is a basic 4FNC with a 29mm motor mount and a payload bay. The instructions are even more minimalist than those for the Screamer II and are printed in such fine print that reading them does not seem to be worth the effort. Construction: As I waited for the epoxy on the motor mount to set up, I turned my attention to the nosecone. It had a 3/4" diameter hole drilled to a depth of about 2". Into that hole, I was instructed to mount a lead fishing weight that came with the kit. I mixed some more epoxy, poured some in the hole, set the weight and then poured the remainder over the top. The fin lines were marked on the BT with a butt template. They were then extended with an angle and 5" slots were cut out with a X-Acto knife. With the fin slots cut, I test fitted the motor mount to find that it was going to need substantial sanding to fit either ring into the BT. The sanding was done and the mount was epoxied into place with the motor tube being flush with the aft end of the rocket. Epoxy was then used to fill space between the centering ring and the end of the BT. After a long hiatus, I managed to put a little more work in on the Screamer. Using 5 minute epoxy, I glued one pair of fins in place. I filleted them with more epoxy using a gloved finger dipped into alcohol to smooth the fillets. These were allowed to set up overnight.
The payload bay is joined to the lower part of the rocket with a tube coupler. The kit comes with a plywood bulkhead to go on one end of the coupler and that is probably my biggest gripe about the kit. The bulkhead is a surface mount. I would much rather have had one that fits in the coupler. Be that as it may, I epoxied the bulkhead in place and tried to ensure that it was even with the edges.
The coupler tube was marked at its halfway point and then a ring of glue was slathered into the base of the payload section. The coupler was then inserted to the mark and set aside to dry. Finishing: After the priming, the rocket sat for a couple of months before I could give it any more attention. I then sanded down the primer and began painting with John Deere Yellow. My target was the BT. The fins and NC would be covered up later.
While assembling the rocket after painting, I realized that I had overlooked the recovery system. I would have like to have attached directly to the motor mount but that was a moot point now. I fashioned a LOC style mount with a loop of heavy nylon cord and some masking tape. It was taped down below the level of the NC shoulder and epoxy was slathered on to keep it in place. I then tied some heavy Kevlar® to the loop and attached a length of 3/8" sewing elastic. One thing I did save intentionally for after painting was the installation of a linear rail lug. I put it is place and started the hole for the upper screw only to realize that I had placed it too high. It interfered with the payload bay coupler. I moved it down about an inch and found the same problem! I finally got it placed right and tapped the holes. The lug was then epoxied on and the screws inserted. The backs of the screws took up the remaining epoxy and the Jane Doe was ready to go. Construction Rating: 3 out of 5 Flight and Recovery:
Flight Rating: 4 out of 5 Summary: Overall Rating: 3 out of 5
What You Can Do
|
||||||||||||
|
|
||||||||||||
With the epoxy on the bulkhead coupler dry, I used some sandpaper to trim down the edges where they protruded past the coupler. When it fit easily into the body tube, I called it finished. I then took the screw eye and screwed it into the pre-drilled hole in the coupler. It seemed like a strong connection but I doused the pointed end with some glue to make sure.
For the John Deere green, I decided to do the nose cone, a ring just below the nose cone, the fins and a narrow strip around the fins. The rocket was masked accordingly and sprayed. When the masking came off, I decided that I rather liked the result.
Ejection and deployment were all textbook. I expected to fly the rocket again but was mystified to see that it had suffered some buckling in the airframe. I can fix it but wonder what caused it since the thrust was not all that heavy.