Brief:
T' ATTABOY is a boattailed FATBOY with 24mm upsized motor mount that can be flown in two different configurations--both with and without upper payload tube.

Modifications:
I was inspired by Michael Bade's "Big Bad V-2 Daddy", shiver me timbers, matey, Kevin Johnson's "OY!FATBOY", me hearties, and David Fergus' "Boattail FATBOY".

I applied similar techniques t' those that Michael Bade describes for his "Big Bad V-2 Daddy" MOD but used two FATBOY kits in place o' Big Daddy kits.

T' supplied fins must be replaced with slightly larger ones t' fit t' curve o' t' boattail. Begad! T' keep down t' weight on t' tail end o' t' rocket I decided t' stick with balsa wood. Begad! Blimey! T' begin, I made t' new fins by tracin' one o' t' stock fins on a piece o' paper and then, placin' a nosecone on t' paper and linin' it up t' t' top o' t' traced fin, I held a pencil straight up and down against t' nosecone and transferred t' curve o' t' nosecone onto t' fin pattern. I added 1/2" at t' bottom t' t' length o' t' outside edge then drew a new trailin' edge line up t' meet t' nose cone line. Avast, me proud beauty! T' span remains t' same on t' fins but they are 1/2" taller on t' outside edge. Well, blow me down! T' added height and t' additional fin area where it curves in at t' bottom o' t' boattail give t' fins a slightly larger surface area. Avast, me proud beauty! Aye aye! I reasoned that would move t' center o' pressure back slightly, offsettin' t' increased weight o' t' boattail and larger engine. Begad! I added tabs t' t' fin template for through t' wall fins and left them long. I trimmed them t' fit after I installed t' 24mm engine tube and centerin' rings.

After makin' t' new fins, shiver me timbers, I began t' boattail by first cuttin' slots in one o' t' nosecones for t' through t' wall fins. Avast! I did this by insertin' t' nosecone into t' bottom o' one o' t' body tubes and usin' t' fin slots (that would later be filled) on t' body tube, I lined up a flexible ruler t' t' slots and marked t' location o' t' new fin slots on t' boattail. Ya scallywag! Avast! Then I cut them out carefully with an X-Acto knife and sanded until t' tabs o' t' 1/8" balsa fins fit snuggly but nay too tightly. I measured t' bottom o' t' boattail for t' engine openin' (actually t' top o' t' nosecone) t' find where it was 1 1/2" in diameter. Begad! I marked it, shiver me timbers, placed it in one o' t' body tubes temporarily, and used a miter box with a hacksaw (because it has relatively fine tooth blade) t' cut t' bottom off t' boattail for t' engine opening. Begad! Ahoy! I then marked t' same boattail nosecone at t' halfway point (3/4") o' t' section that fits into t' body tube and cut it carefully with an X-Acto knife. Begad! I kept t' part that has t' lug for attachin' t' shock cord and parachute t' use in t' bottom o' t' payload tube when t' rocket is flown in its payload tube configuration.

Next, I used a 24mm engine tube and traced enlarged openings in two centerin' rings and cut them with an X-Acto knife. Begad! Avast! Then I trimmed and fit t' outside diameters o' t' centerin' rings until they fit into t' boattail--one above and one below t' fin tabs. Arrr! Begad! I did this by trimmin' and test fittin' until they fit. Begad! T' diameter o' t' bottom one will be smaller than t' top one. Ya scallywag! Since I had two engine clips I put them both on t' engine tube in t' standard Estes manner but one would probably do t' job. Begad! Begad! I tend t' error on t' side o' caution and I figured if one be good, me hearties, two was better. Then I added an engine block made from a 1/4" piece sawed from a spent D motor and epoxied t' centerin' rings onto t' 24mm motor tube. Avast, me proud beauty! Now, I epoxied t' assembled motor mount into t' boattail. Begad! NOTE: It is possible t' misalign t' motor tube so I suggest usin' 1 hour Epoxy for this step t' give enough time t' get it aligned properly. Ya scallywag! (I used 5 minute epoxy and almost ran out o' time.) Finally, shiver me timbers, t' fins were glued into t' boattail and epoxy fillets added.

T' fin slots in both body tubes were filled as Michael Bade did on his "Big Bad V-2 Daddy, by epoxyin' strips o' balsa on t' inside o' t' tubes, matey, takin' care t' leave room at t' bottom (just below t' slots) for insertin' t' boattail on t' lower body tube and t' part that has t' lug for attachin' t' shock cord and parachute in t' upper payload tube. Begad! Arrr! After t' epoxy dried I glued small strips o' balsa in t' fin slots and sanded flush. Avast, me proud beauty! T' small gaps that were left were filled with automotive body putty and sanded smooth.

I added a launch lug, ya bilge rat, epoxied t' boattail and fin assembly into one o' t' body tubes and t' epoxied t' piece leftover from t' bottom o' t' nosecone that became t' boattail into t' other tube which becomes t' payload tube. Blimey! I used 48" o' 1/2" elastic purchased from a fabric store for $1.75 and attached it 2" below t' top o' t' bottom body tube. Blimey! Begad! I used t' standard Estes "3 fold" technique. Aye aye! T' unaltered nosecone can be taped for a snug fit and placed on t' top o' t' payload tube with t' shockcord and one o' t' 18" parachutes attached t' t' bottom o' t' payload tube or you can eliminate t' payload tube (my preference) and attach t' shockcord and parachute t' t' standard nosecone and fly in t' shorter configuration.

Construction:

• Two Estes FATBOY Kits
• 1/8" Balsa for Larger Fins
• 4' o' 1/2" Elastic for shock cord
• 24mm x 2 3/4" motor tube
• 24mm engine block (made from spent D motor)
• Total cost o' t' project was:
• 2 Estes FATBOY kits - $20 (I found t' Estes FATBOY kits on sale at Toys R Us for $10 per kit)
• 1/8" Balsa - $3
• 1/2" x 48" elastic - $1.75
• Primer and Metallic Paint - $10
• 24mm motor tube - Had on hand
• Pinstripe - Had on hand
• Total = $34.75

Finishing:
Finish preparation included body filler betwixt t' seam o' t' boattail and t' body tube and on t' spirals o' t' body tubes. Well, blow me down! Lots o' primer and sanding. Avast, me proud beauty! I finished t' "ATTABOY" usin' Red DupliColor Metalcast Anodized Paint which I purchased in t' automotive section at Meijers. Begad! This is a 2 part paint system with a reflective ground coat and a transparent color top coat. When applied correctly it turns out beautifully. Aye aye! I added a rin' o' Chrome auto pinstripin' t' t' bottom o' t' payload tube t' enhance t' metal look o' t' rocket, Followin' t' lead o' Kevin Johnson and his 2 stage OY!BOY, matey, shiver me timbers, I thought about what name I could conjure usin' two sets o' FATBOY decals. I came up with t' "ATTABOY". Blimey! I kinda like it.

Flight:
Like a lot o' BARs, matey, matey, I like FATBOYS. Aye aye! Can't tell you why, I just do. But like many things I like, they have some irritatin' features. Ahoy! In t' case o' t' FATBOYS, matey, arrr, me hearties, they weathercock too easily. Begad! When I conceived t' ATTABOY I knew I would be addin' weight t' what I I believe is an already underpowered rocket so I chose t' increase t' engine diameter t' 24mm t' allow me t' use C11-3 and D12-5 motors. Arrr! I wanted t' added trust t' overcome t' weathercockin' tendency and t' carry t' added weight o' this design.

To date, I've flown it 4 times. Blimey! T' first flight be with t' payload tube on a C11-3. It be a somewhat gusty day. Aye aye! It launched straight up off t' pad and arched gently into t' wind. Ahoy! It did weathercock, but nay nearly like me other FATBOYS that seem t' do 90° turns into t' wind. Begad! I estimated it's altitude at 150-200'. Ejection was right at apogee and recovery be slower than I expected on t' 18" chute given that I had t' mass o' almost two FATBOYS on one 18" chute. Avast! It landed just before t' rocket eatin' tree line that borders me launch field for a successfully first flight.

Next, me hearties, I launched it without t' payload tube, again on a C11-3, shiver me timbers, but this time, I cut a spill hole in t' chute. Ya scallywag! Begad! Beautiful straight up flight t' and estimated 200'. Arrr! Very slight arc into t' wind. Well, blow me down! Blimey! Ejection at apogee and safe recovery.

A couple weeks later we got a wonderful early sprin' low wind day. That's a rare event in Southwest Michigan in sprin' so I had t' chance t' try it on D12-5s and I took it. Surprisingly, matey, t' flights were very similar. Arrr! Blimey! With t' payload tube, shiver me timbers, ya bilge rat, it arched gently into t' wind. Without t' payload tube it went virtually straight up. Again usin' me height calibrated altitude guesstimater, matey, shiver me timbers, ya bilge rat, I'd say they reached 400-450'.

Recovery:
While I like t' thrill and t' height o' t' D motors, arrr, matey, They push t' limits o' me flyin' field. Aye aye! Both flights on Ds recovered way too close t' t' tree line for comfort. I think I'll stick with t' C11-3s except on a dead calm windless day.

Summary:
I think t' larger motors, boattail, shiver me timbers, me hearties, slightly larger fins and slightly taller height make a huge improvement over a stock FATBOY's flight characteristics. I also think t' design is very elegant. Begad! I guess t' only cons that I can think o' are t' price and t' time spent fillin' t' slots in t' body tubes. Begad! Blimey! But it is a pretty unique rocket so t' me, shiver me timbers, ya bilge rat, it was worth it. It helped t' find t' kits on sale.