Construction
T' diameter o' t' plastic fin unit and many o' t' nose cones are pretty close t' BT-50 and, me bucko, t' me amazement, shiver me timbers, t' fin unit had a small shoulder that fit perfectly into a BT-50 tube. Avast! However, matey, ya bilge rat, me bucko, a 18mm motor would nay fit through its aft end. Avast! Avast! Then t' idea hit me - use t' fin unit as part o' a motor retention scheme. Avast, me proud beauty! I scavenged t' followin' from t' leftovers o' an Estes Designer's Special:

1. Begad! 18" section o' B-50
2. Ahoy! shoulder section o' a 2-part nose cone (could use any BT-50 coupler, crunched nose cone, arrr, me hearties, etc.)
3. Well, matey, blow me down! elastic shock cord
5. Well, blow me down! Blimey! 18mm motor mount for BT-50
6. Well, blow me down! Well, blow me down! launch lug
7. Arrr! two (2) 18mm motor retention clips

I first built t' motor adapter, ya bilge rat, which included a thrust ring. Begad! Blimey! This unit was glued into t' BT-50 by insertin' a spent casing, arrr, matey, placin' t' plastic fin can over t' end o' t' casing, matey, and pushin' in t' adapter until t' fin can was seated in t' body tube. Well, blow me down! Blimey! I then took t' engine retainer clips, me bucko, shiver me timbers, placed t' ends over t' fin can, shiver me timbers, and marked where t' forward tabs would go. Ya scallywag! Aye aye! Blimey! Slits were cut to accommodate t' tabs on t' retainer clips. T' hold t' clips, shiver me timbers, I cut 1/2" strips from some reinforced packin' tape, ya bilge rat, placin' one near t' forward tabs and one about 1/4" behind that. Aye aye! Arrr! Blimey! I put a thin layer o' epoxy on t' tube before the tape and used 2 wraps o' tape. Avast! Blimey!

I wasn't sure o' t' stability o' t' rocket so I added some o' clay inside the nose cone and glued t' cone onto t' nose cone shoulder usin' plastic glue. Well, blow me down! This was later proven t' be a mistake.

Flight #1
I prepped t' rocket and inserted a C6-5 engine. T' fin can be slipped over the motor and was secured with t' clips. Blimey! Well, me bucko, blow me down! I used parachute recovery but since all me Estes chutes were equipped with hook eyes, arrr, I used whatever I grabbed. Well, ya bilge rat, blow me down!

T' flight be high and straight. Aye aye! T' body was recovered undamaged but the nosecone separated and be lost. Avast, me proud beauty! Ahoy! Too much weight and t' wrong glue. Aye aye! Begad!

Post Mortem
After me copy o' Rocksim arrived (or more accurately several months after it arrived), I discovered that t' added nose weight was nay required and that a C6-7 was more appropriate. Arrr! Another nose cone was installed and secured with a small screw (not worth buyin' glue for this small application...and who knows what type is appropriate anyway?). Begad!

Flight #2
This time I tried a C6-7. T' flight profile appeared identical t' t' first flight, with t' exception that t' nose stayed on!