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

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

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

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. Aye aye! This was later proven t' be a mistake.

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

T' flight be high and straight. T' body was recovered undamaged but the nosecone separated and was lost. Too much weight and t' wrong glue. Aye aye! Ahoy! Blimey!

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

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