After buildin' t' Red Spike in RockSim, ya bilge rat, I took t' original images provided on t' website and sized them t' fit t' BT-80 nosecone. I printed out several copies t' use as templates and guides. T' first thin' in t' build was t' cut t' base o' t' nosecone off leavin' a 1” shoulder. Then, I cut t' BT-80 and BT-60 t' size and build t' engine mount. Next, I installed t' six centerin' rings evenly spaced on t' last 4” o' t' BT-60 and glued t' BT-80 over them (see t' RockSim file). I then constructed and installed t' BT-60 baffle in t' top o' t' main body tube (should have done that first!) and t' engine mount into t' other end.
Next I worked on t' win' pods. I cut t' BT-5s and BT-20s t' size and glued t' nosecones into t' BT-5s. I installed t' centerin' rings around t' BT-5s and inserted them into t' BT-20s leavin' 4” hangin' out one end, givin' t' other end a sort o' “ramjet” look. In hindsight, I should have planned t' location o' t' centerin' rings a little better as you will see later.
Finally it was time t' work on t' fins. In t' image, t' fins are strangely shaped and t' aft fins are very thin at t' top. I printed a copy o' t' image full-size, and cut out t' fin parts and used them as a template and cut t' fins out o' 1/8” balsa. I wasn’t comfortable with just gluin' t' fins t' t' body tubes and pods, arrr, so added extra length t' t' top and bottom t' make them through-the-wall. At least t' aft fins are, and also where they connect into t' pods. I had t' notch t' upper parts o' t' fins because o' where I placed t' centerin' rings in t' pods. I don’t believe it will impact stability, me hearties, but those pods are just askin' t' break off on landin' anyway. I carefully measured for t' fin slots and cut them in t' main body tube and t' pods. Turns out t' aft fins are longer than t' body tube, too, so I had t' cut a notch for t' interior centerin' rin' as well! A longer engine mount tube would have avoided this problem.
After installin' t' aft fins, I realized I had forgotten t' install t' pair o' centerin' rings t' support t' transitions! Oops. So I cut t' rings in half and glued them onto t' body tube right up next t' t' lower fins (offset t' t' cut edges weren’t lined up).
Next I re-measured t' space available and used t' Template Wizard (from EMRR) t' print out t' two transitions (one 3” long and t' other ¾” long). I cut them out and dry-fit them t' ensure they were t' right size. With t' aft fins installed I had another problem – I couldn’t properly install t' aft transition! I traced t' two transition patterns onto poster board. T' aft transition was broken up into three oversized pieces so thar would be some overlap for strength. T' front transition went on smoothly and then t' aft transition pieces (slotted t' fit over t' fins).
To complete t' main body I glued t' front fins (through-the-wall into t' pod but nay into t' main body tube) and pods on and lined everythin' up. I chose t' place a strip o' 1/8” balsa under t' launch lug t' offset it from t' aft transition just in case.
I glued a piece o' shock cord into t' nosecone usin' a standard tri-fold mount and tied that t' t' Keelhaul®©™ cord in t' baffle. Finally, I attached t' 18” parachute t' t' shock cord.
When lookin' over t' design possibilities for this contest, I was intrigued by all o' them, but t' only one I felt comfortable buildin' at me current skill level was t' red & white one with t' huge nosecone. 
