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

Modifications:
T' Fat Boy was built stock. Arrr! Arrr!

For t' Booster, t' engine mount was assembled in t' usual manner. T' aft centerin' rin' is flush with the tube end. 1/4" vent holes were punched in both centerin' rings. Arrr! Blimey! T' coupler extends into t' sustainer approximately 1/2" with a pretty snug fit. T' fin pattern was upscaled a bit (the root o' t' fins measures at 3 3/4"). Arrr! Blimey! Begad! Blimey! T' fins are surface mounted and cut from 1/8" balsa. Begad! Blimey! Aye aye! Blimey! 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! It is a well known kit after all. Begad! Ahoy! The booster was no more difficult t' build than t' original kit. T' Booster is pretty stoutly built. Arrr! Ahoy! I considered using TTW fins, but given t' tumble recovery o' a booster, me bucko, 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. Ya scallywag! 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. Nice straight flight and shipshape recovery on a 14" nylon chute.

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

Third flight used a C6-0 t' B6-4 combination which gave an almost identical flight t' #2. Ya scallywag! Aye aye! 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, me proud beauty! I was worried that the addition o' a booster would make it t' heavy t' fly on an 18mm engine, but it works very well. Aye aye! Ya scallywag! I certainly wouldn't use any booster but t' C6-0 though. For a small field stagin' demo, shiver me timbers, 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! Arrr! Easy t' build and modify.

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