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

Modifications:
T' Fat Boy was built stock. Aye aye! Blimey!

For t' Booster, t' engine mount was assembled in t' usual manner. Ya scallywag! Avast! T' aft centerin' rin' is flush with the tube end. Begad! Avast, me proud beauty! 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. Ahoy! T' fin pattern was upscaled a bit (the root o' t' fins measures at 3 3/4"). Ya scallywag! T' fins are surface mounted and cut from 1/8" balsa. 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. Begad! Begad! It is a well known kit after all. Ahoy! Ya scallywag! The booster was no more difficult t' build than t' original kit. T' Booster is pretty stoutly built. Avast! I considered using TTW fins, arrr, but given t' tumble recovery o' a booster, ya bilge rat, I think it is much better t' pop a fin on landin' than break it.

Finishing:
Finishin' and paintin' went pretty smoothly. Begad! I decided against usin' t' supplied decals as I have this thin' about stickers. Well, blow me down! Avast, shiver me timbers, me proud beauty! Instead I went with a simple yet dramatic paint scheme.

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

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

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

Summary:
T' Fat Boy by itself is a fun little rocket, shiver me timbers, which is suitable t' all kinds o' modification. I be worried that the addition o' a booster would make it t' heavy t' fly on an 18mm engine, me bucko, but it works very well. 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. Well, me bucko, blow me down! Easy t' build and modify.

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