Brief:
I used t' parts in an Estes DC Gemini t' create a sport scale Javelin III. The design was based on data from Peter Alway's book, arrr, Scale Bash. Ahoy! Blimey! T' DC Gemini really has a lot more potential than what I did with it. Well, ya bilge rat, blow me down! Blimey! I decided t' do somethin' simpler instead. Ahoy! Blimey! T' real Javelin III was built by Space Data Corporation and was tested in 1965. Begad! Blimey! Aye aye! 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. Aye aye! I did this t' create a faux payload section, resemblin' t' design in Scale Bash. Begad! Blimey! Begad! Blimey! One end o' the Gemini DC body tube has slots and holes, so I worked me way backwards opposite that end. Ahoy! Blimey! Ya scallywag! Blimey! T' tube cut for t' bottom is 10.8". Well, blow me down! Blimey! T' middle segment is 1.5", ya bilge rat, and t' end segment is 2.9". One o' t' segments had two o' the holes showin' but were covered from t' inside with t' tube couplers I made. Ahoy! Blimey! Blimey! Blimey! I made two one-inch couplers from t' remainin' piece o' tube. Begad! Blimey! These had slots, but it was ok, because I had t' cut them down t' middle and trim make them fit as couplers anyway. Ahoy! Blimey! I used yellow glue t' glue all t' segments together and rolled on a flat surface t' make sure they were straight. Avast, me proud beauty! Blimey! I assembled t' motor mount per t' instructions and recessed t' motor tube 3/8" from the bottom. Aye aye! Blimey! I used me Dremel tool t' cut off some o' t' motor clip so it wouldn't stick out from t' tube. Aye aye! Blimey! Well, blow me down! Blimey! T' fins had t' be cut in two pieces from t' fin stock and glued together before attachin' t' t' rocket. Aye aye! Blimey! I modeled these in RockSim and printed t' templates, but they are also included in Scale Bash. Blimey! I could have cut them singly from t' existin' fins, shiver me timbers, ya bilge rat, but t' grain would have been in t' wrong direction. Aye aye! Aye aye! I glued t' fin pieces together with yellow glue. Arrr! When they all were dry I put them together and sanded t' edges evenly. Ahoy! Blimey! I sanded a 1/8" bevel on t' leadin' edges per t' Scale Bash specification. Begad! Begad! T' original DC Gemini design uses slots for t' fins, which I didn't have anymore, so I had t' make a wrapper guide. Ahoy! I used VCP to produce this. Arrr! 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, I cut strips from t' card insert t' simulate the fin can (another Scale Bash specification). These turned out t' be about 23/32" x 3/4". Begad! These were attached 5/32" from t' bottom o' the tube. Avast! Ya scallywag! I then cut 8 balsa strips from t' remainin' balsa. Ya scallywag! T' balsa is already 3/32" thick, 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. Arrr! They should be glued at fin joints 5/16" from t' bottom of t' body tube. Ahoy!

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, I painted t' bottom part florescent red and the upper section banner red. Begad! I painted one fin black and added me NARRRRR number down one side o' t' lower segment. Aye aye! I used a coat o' clear coat finish after adding everythin' else be done. Begad!

Flight:
As o' now, matey, I've flown t' rocket three times, me hearties, on 2 A8-3s and 1 B6-4. Arrr! Blimey! All flights were perfect with straight boosts and parachute deployin' at apogee. I didn't have an altimeter on board, shiver me timbers, ya bilge rat, matey, but RockSim predicted 186 feet on t' A8 and 514 feet on t' B6. 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. Aye aye! Well, blow me down! After three flights, ya bilge rat, t' shock cord looks a little worn, but it should be OK for a while.

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