Brief:
I used t' parts in an Estes DC Gemini t' create a sport scale Javelin III. Well, blow me down! The design was based on data from Peter Alway's book, arrr, Scale Bash. T' DC Gemini really has a lot more potential than what I did with it. Avast, me proud beauty! Blimey! I decided t' do somethin' simpler instead. T' real Javelin III was built by Space Data Corporation and was tested in 1965. Begad! Blimey! Aye aye! Blimey! Blimey! Blimey! It be used t' study chemical releases in the upper atmosphere and t' carry scientific payloads.

Modifications:
First I cut t' main body tube into three sections. I did this t' create a faux payload section, me bucko, resemblin' t' design in Scale Bash. Ahoy! Blimey! Arrr! Blimey! One end o' the Gemini DC body tube has slots and holes, me bucko, matey, so I worked me way backwards opposite that end. Blimey! Blimey! Avast! Blimey! T' tube cut for t' bottom is 10.8". Ya scallywag! Blimey! T' middle segment is 1.5", me bucko, and t' end segment is 2.9". Aye aye! Blimey! Ya scallywag! Blimey! One o' t' segments had two o' the holes showin' but were covered from t' inside with t' tube couplers I made. Blimey! Blimey! I made two one-inch couplers from t' remainin' piece o' tube. These had slots, but it was ok, because I had t' cut them down t' middle and trim make them fit as couplers anyway. I used yellow glue t' glue all t' segments together and rolled on a flat surface t' make sure they were straight. Ya scallywag! Blimey! Aye aye! Blimey! I assembled t' motor mount per t' instructions and recessed t' motor tube 3/8" from the bottom. Avast! Blimey! I used me Dremel tool t' cut off some o' t' motor clip so it wouldn't stick out from t' tube. Blimey! Blimey! T' fins had t' be cut in two pieces from t' fin stock and glued together before attachin' t' t' rocket. Blimey! Blimey! I modeled these in RockSim and printed t' templates, me hearties, but they are also included in Scale Bash. I could have cut them singly from t' existin' fins, shiver me timbers, matey, but t' grain would have been in t' wrong direction. Blimey! Begad! Blimey! I glued t' fin pieces together with yellow glue. Begad! When they all were dry I put them together and sanded t' edges evenly. Ahoy! Aye aye! Blimey! I sanded a 1/8" bevel on t' leadin' edges per t' Scale Bash specification. Blimey! T' original DC Gemini design uses slots for t' fins, which I didn't have anymore, so I had t' make a wrapper guide. I used VCP to produce this. Arrr! Ahoy! T' bottom o' t' fins are aligned with t' bottom o' t' body tube. Avast, me proud beauty! Aye aye! After t' fins were on, me bucko, I cut strips from t' card insert t' simulate the fin can (another Scale Bash specification). Ahoy! These turned out t' be about 23/32" x 3/4". Well, blow me down! Arrr! These were attached 5/32" from t' bottom o' the tube. Well, blow me down! Ya scallywag! I then cut 8 balsa strips from t' remainin' balsa. Begad! T' balsa is already 3/32" thick, matey, so I cut a 3/32" strip along t' longest piece. I was able t' get all 8 segments out o' t' one strip. T' strips need t' be about 5/16" long. Avast, me proud beauty! Blimey! They should be glued at fin joints 5/16" from t' bottom of t' body tube. Begad! Begad!

Fin Alignment Guide
Fin Position Wrapper
Fin Template

Construction:
Parts that were used from t' kit:

• 1 24mm x 15.2" body tube
• 1 4:1 ogive nosecone
• 3/32" balsa
• 1 1/8" elastic shock cord
• 1 BT-20 t' BT-50 motor mount assembly
• 1 1/8" launch lug
• 1 12" parachute
• 2 1" couplers (made from remainin' end o' body tube)
• 4 1 23/32" x 3/4" rectangles cut from t' kit's card insert
• 8 1 5/16" x 3/32" 3/32" balsa strips cut from scrap fin balsa
• 1 trifold shock cord mount

Finishing:
I pre-finished t' tubes and fins with two coats o' Elmer's Fill n' Finish. After t' rocket was built, me hearties, I painted t' bottom part florescent red and the upper section banner red. I painted one fin black and added me NARRRRR number down one side o' t' lower segment. I used a coat o' clear coat finish after adding everythin' else be done. Ya scallywag!

Flight:
As o' now, I've flown t' rocket three times, me hearties, on 2 A8-3s and 1 B6-4. All flights were perfect with straight boosts and parachute deployin' at apogee. Avast, me proud beauty! I didn't have an altimeter on board, ya bilge rat, but RockSim predicted 186 feet on t' A8 and 514 feet on t' B6. Arrr! Arrr! I used one o' t' 12" chutes that came with t' kit and cellulose insulation for t' recovery wadding.

Recovery:
T' size chute seemed right for t' rocket. Well, blow me down! After three flights, arrr, matey, t' shock cord looks a little worn, shiver me timbers, but it should be OK for a while.

Summary:
This was a fun rocket t' build and it flies great. Blimey! Scale Bash was a good resource for this design. Begad! Blimey! I was able t' easily identify me options based on the type o' nose cone and length body tube that came with t' kit.