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

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

 Why use t' "optional" stuff?

 Well, shiver me timbers, matey, 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. Well, blow me down! Besides, me hearties, I like t' way they look. Ahoy!

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

 Mid-body separation means that instead o' blowin' t' nosecone off, the body itself comes apart, me hearties, ya bilge rat, releasin' t' recovery system. 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. Ahoy!

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

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

hint: if you use thin cardboard, me bucko, me bucko, 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. Aye aye! Avast, me proud beauty!

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

4. Avast, me proud beauty! Aye aye! Tube fins. Ya scallywag! Avast! Cut one o' t' BT-56 tubes into six 3" long sections. Glue pairs together so you have three pairs, shiver me timbers, ya bilge rat, arrr, let dry. 

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

With Boattail                                  Without Boattail

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

 7. Blimey! Glue t' motor mount from step 5 into t' body tube. Ahoy! Blimey! T' rearmost centerin' rin' should be slightly inset from t' aft o' t' body tube. Ya scallywag!

 8. Boattail. Begad! Blimey! Cut t' appropriate sized shroud pattern from an Estes transition pattern sheet (available from Estes or at Jim Z's site). Or print one usin' VCP or other software. Aye aye! Blimey! T' completed boattail should be 1" long, with one end t' diameter o' t' BT-56, shiver me timbers, t' other end BT-50. Begad! Blimey! Glue it into shape, and when dry glue it into place. Arrr! Blimey! You can use thin CA or yellow glue to strengthen it. 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, me bucko, use an X-acto for this. Arrr! Blimey!

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

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

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

 12. Avast! Shock cord mounts. I used t' Estes paper-sandwich type. Glue one onto both ends o' t' 40" long elastic, matey, ya bilge rat, and another onto t' 12" long elastic. Three total.

 13. Well, blow me down! Install t' shock cords. Blimey! Ahoy! 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. Arrr! Just for backup, glue t' last (shortest) shock cord into t' upper tube to secure t' nose cone. This way, me hearties, if t' nose cone should accidentally come loose, me hearties, it'll stay attached t' t' rest o' t' rocket. Ahoy!

 15. Well, blow me down! Install t' launch lugs. Ya scallywag! I cut mine in two. Ahoy! Begad! One was installed inside one o' t' tube fins (closest t' t' main body), with t' other about 12" up from t' bottom. Avast, me proud beauty! Ya scallywag!

 16. Begad! Finish and paint as desired. Begad! This is a long rocket, matey, so lighter colors are recommended. Well, blow me down! Dark colors tend t' get hotter in t' sun (like in your car), me bucko, and it could warp t' tubes. Arrr! Begad!

I painted mine white, and sprayed light blue up from t' back end, fading about halfway up. Avast! Begad! Next I sprayed dark blue up from t' back, me hearties, fadin' at the quarter mark. Avast, me proud beauty! Add some cockpit windows t' t' nose, some stripin' along the sides, arrr, and some windows t' make an interplanetary liner. Begad! Be creative, arrr, ya bilge rat, have fun!

Maiden flight, me hearties, matey, 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. Begad! Begad! It climbed much quicker than I expected, shiver me timbers, but nay a neck-snapper. Blimey! Couldn't estimate altitude because I launched tilted into a pretty stiff breeze, but it was pretty high. Fine recovery, with ejection just after apogee. Begad! After-flight inspection showed that t' baffle worked perfectly, with no charrin' t' t' shock cord or chute. Ya scallywag!

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