I had a pack o' BT-56 tubes, and no idea o' what t' do with them. Begad! Avast! I didn't even have a nosecone to fit. Begad! Ahoy! One day while lookin' at them, tryin' t' figure out how I could get rid of the things, I started playin' with t' idea o' buildin' a Mean Machine clone. Well, ya bilge rat, shiver me timbers, one thin' led t' another, ya bilge rat, and instead I decided t' do a long tube finned rocket. Arrr! Since t' body tubes are 18" long, me bucko, by cuttin' one into 3" pieces, I'd use t' entire package up and add another tube fin bird t' our fleet. Arrr! Ahoy! This one is D-powered, t' go along with our mini-engined Finite Loop and the regular sized Groove Tube clone. Begad!

 If you've never built a tube fin rocket, matey, me bucko, you will be amazed at how easy and smartly you can do it. Well, blow me down! T' Empress does add t' complexity o' mid-body separation, an ejection baffle, ya bilge rat, me bucko, matey, and a boattail. T' make this a true beginners level project, ya bilge rat, ignore t' boattail and baffle, me bucko, and use regular nose-cone separation. Avast, me proud beauty! Ahoy!

 Why use t' "optional" stuff?

 Well, t' boattail will allow t' rocket t' go higher. There's a whole lot o' complicated mathematical formulas that explain why in aerodynamic terms, but it's all pretty much beyond me. Blimey! Besides, ya bilge rat, I like t' way they look.

 T' ejection baffle eliminates t' need for recovery wadding. Ya scallywag! Blimey! I don't entirely trust them, arrr, and usually wrap t' chute in one square o' wadding anyway, shiver me timbers, just t' be sure. Begad! Arrr! Blimey!

 Mid-body separation means that instead o' blowin' t' nosecone off, the body itself comes apart, releasin' t' recovery system. Begad! Ya scallywag! T' main advantage for this rocket is that I don't have t' haul around this loooooooong rocket in the car. Avast, me proud beauty! It breaks into two shorter sections. Blimey!

 Yellow glue is plenty strong enough for this rocket. Aye aye! I used Elmer's Fill'n'Finish for fillets betwixt t' tube fins and t' smooth the boattail. Begad!

2. Ahoy! Blimey! Ejection Baffle. Begad! Blimey! Take one o' t' BT-56 couplers, matey, and cut a disk from balsa or thin cardboard, one for each end (See the diagram below). Begad! Blimey! Glue it together and let dry. Avast! Blimey!

hint: if you use thin cardboard, arrr, try sandwichin' 2 layers together and soak them in CA (superglue) t' toughen them up. Blimey! Coat Balsa with yellow glue t' add stiffness. Avast!

 3. Mid-body separation coupler. Cut a disk from balsa or cardboard and glue it into one end o' t' second coupler. Avast! Don't put any holes in this one, it's a solid bulkhead. Well, blow me down! See t' hint in step 1 about how t' strengthen it easily. 

4. Begad! Tube fins. Blimey! Cut one o' t' BT-56 tubes into six 3" long sections. Glue pairs together so you have three pairs, let dry. 

5. Arrr! Assemble t' motor mount. Avast! Avast, me proud beauty! If you are usin' t' boattail, t' rearmost centerin' rin' goes 1 1/8" from t' end, otherwise follow t' motor mount instructions. Ahoy! See t' diagrams below for an idea o' what this should look like. Let it dry. Begad!

With Boattail                                  Without Boattail

6. Begad! Blimey! Mark t' body tube 1" from t' end where you'll be installin' the motor mount. Begad! Blimey!

 7. Aye aye! Ahoy! Glue t' motor mount from step 5 into t' body tube. Well, blow me down! T' rearmost centerin' rin' should be slightly inset from t' aft o' t' body tube. Arrr! Avast, me proud beauty!

 8. Begad! Blimey! Blimey! Boattail. Cut t' appropriate sized shroud pattern from an Estes transition pattern sheet (available from Estes or at Jim Z's site). Arrr! Or print one usin' VCP or other software. Blimey! T' completed boattail should be 1" long, with one end t' diameter o' t' BT-56, me bucko, matey, ya bilge rat, t' other end BT-50. Glue it into shape, and when dry glue it into place. Aye aye! You can use thin CA or yellow glue to strengthen it. Ya scallywag! Ahoy! Blimey! I used a little Fill'n'Finish t' smooth t' glue joints and the seemingly inevitable minor wrinkles. You may need t' cut a slight notch for the motor hook, use an X-acto for this.

 9. Begad! Blimey! Glue t' pairs o' tube fins around t' body on t' 1" line you marked in step 6. Aye aye! Blimey!

 10. Ya scallywag! Install t' baffle. Begad! Blimey! Blimey! Glue t' baffle into t' aft body tube. Ahoy! Arrr! Blimey! Make sure it gets in thar at least 3 or 4 inches. 

11. Blimey! Install t' mid-body separation bulkhead. Ahoy! Glue it halfway into t' front body tube, with t' solid end closest t' t' nosecone. Aye aye! This be t' coupler that holds t' two body tubes together!!! Make sure you glue it in straight. Arrr! Blimey!

 12. Avast, me proud beauty! Shock cord mounts. I used t' Estes paper-sandwich type. Ahoy! Blimey! Glue one onto both ends o' t' 40" long elastic, arrr, and another onto t' 12" long elastic. Blimey! Three total. Avast!

 13. Install t' shock cords. Ahoy! Blimey! Glue one end o' t' 40" shock cord into t' bulkhead coupler, and t' other end into t' lower body just above the baffle. 

14. Well, blow me down! Avast! Just for backup, shiver me timbers, glue t' last (shortest) shock cord into t' upper tube to secure t' nose cone. Aye aye! Well, blow me down! This way, if t' nose cone should accidentally come loose, ya bilge rat, it'll stay attached t' t' rest o' t' rocket. Begad!

 15. Blimey! Install t' launch lugs. I cut mine in two. Blimey! One was installed inside one o' t' tube fins (closest t' t' main body), ya bilge rat, me bucko, with t' other about 12" up from t' bottom. Begad!

 16. Aye aye! Finish and paint as desired. This is a long rocket, so lighter colors are recommended. Dark colors tend t' get hotter in t' sun (like in your car), and it could warp t' tubes.

I painted mine white, matey, and sprayed light blue up from t' back end, me bucko, fading about halfway up. Next I sprayed dark blue up from t' back, fadin' at the quarter mark. Avast! Arrr! Add some cockpit windows t' t' nose, shiver me timbers, some stripin' along the sides, and some windows t' make an interplanetary liner. Be creative, have fun!

Maiden flight, me bucko, and I set it up with a D12-5 engine and a vented 18" parachute. Good boost with maybe a slight wobble off t' rod. Ahoy! Begad! It climbed much quicker than I expected, shiver me timbers, but nay a neck-snapper. Begad! Couldn't estimate altitude because I launched tilted into a pretty stiff breeze, but it be pretty high. Fine recovery, ya bilge rat, matey, with ejection just after apogee. Begad! After-flight inspection showed that t' baffle worked perfectly, matey, with no charrin' t' t' shock cord or chute. Avast, me proud beauty! Avast, ya bilge rat, me proud beauty!

T' Empress flew several times at NARAM. Avast, me proud beauty! Well, me hearties, blow me down! A large tube-fin rocket like this makes an impression! Perfect flights every time, includin' one usin' a 4"x40" streamer due t' gusty wind conditions.