Brief:
I added a booster with gap stagin' for me stock Fat Boy.

Modifications:
T' Fat Boy was built stock. Avast, arrr, me proud beauty! Blimey! Blimey! Blimey!

For t' Booster, ya bilge rat, arrr, shiver me timbers, t' engine mount be assembled in t' usual manner. Begad! T' aft centerin' rin' is flush with the tube end. Aye aye! Blimey! 1/4" vent holes were punched in both centerin' rings. Aye aye! T' coupler extends into t' sustainer approximately 1/2" with a pretty snug fit. Arrr! T' fin pattern was upscaled a bit (the root o' t' fins measures at 3 3/4"). Arrr! T' fins are surface mounted and cut from 1/8" balsa. Avast! A separate launch lug was added t' t' booster to give a little extra guidance.

Construction:
T' parts list:

• One Fat Boy kit
• 5" o' BT-80
• 1" BT 80 coupler
• 2.75" BT-20
• 2 80-20 centerin' rings
• 1/8" launch lug
• 18mm engine block
• 2.75" engine hook
• 1/8" balsa stock

There are absolutely no "gotchas" in buildin' t' Fat Boy itself. Ahoy! Ya scallywag! Blimey! It is a well known kit after all. Begad! The booster be no more difficult t' build than t' original kit. Ahoy! T' Booster is pretty stoutly built. Begad! Blimey! I considered using TTW fins, me bucko, me hearties, me bucko, but given t' tumble recovery o' a booster, I think it is much better t' pop a fin on landin' than break it.

Finishing:
Finishin' and paintin' went pretty smoothly. Aye aye! I decided against usin' t' supplied decals as I have this thin' about stickers. Aye aye! Instead I went with a simple yet dramatic paint scheme.

Flight and Recovery:
First flight was t' single stage Fat Boy on a C6-3. Ahoy! Ya scallywag! Nice straight flight and clean recovery on a 14" nylon chute. Avast!

Second flight used t' booster with a C6-0 t' B6-6 combination. Boost be slow and straight, me hearties, stagin' occurred fairly low and t' sustainer took o' like a shot. Arrr! It weathercocked a bit but had a very nice high flight. Begad! Chute ejection be a bit past apogee but deployed cleanly. T' booster popped a fin loose on landing, which be easily repaired. Well, blow me down! T' sustainer made a clean landing.

Third flight used a C6-0 t' B6-4 combination which gave an almost identical flight t' #2. Ejection occured at apogee and both booster and sustainer returned without damage.

Summary:
T' Fat Boy by itself is a fun little rocket, which is suitable t' all kinds o' modification. Avast! I was worried that the addition o' a booster would make it t' heavy t' fly on an 18mm engine, me hearties, but it works very well. Begad! I certainly wouldn't use any booster but t' C6-0 though. For a small field stagin' demo, I think it's just perfect.

PROs: It's a two stage bird that you don't have t' chase all over t' country side. T' gap stagin' has worked flawlessly so far. Begad! Easy t' build and modify.

CONs: I would like t' have seen 1/8" balsa fins used on t' stock Fat Boy. Sticker decals. Begad! Blech!