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

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

 Why use t' "optional" stuff?

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

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

 Mid-body separation means that instead o' blowin' t' nosecone off, the body itself comes apart, me hearties, 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. Begad! Blimey! It breaks into two shorter sections. Avast, me proud beauty! Blimey!

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

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

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

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

4. Arrr! Tube fins. Ahoy! Arrr! Cut one o' t' BT-56 tubes into six 3" long sections. Glue pairs together so you have three pairs, shiver me timbers, me bucko, let dry. 

5. Arrr! Assemble t' motor mount. Ahoy! Well, blow me down! If you are usin' t' boattail, t' rearmost centerin' rin' goes 1 1/8" from t' end, me hearties, 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. Blimey! Begad! Mark t' body tube 1" from t' end where you'll be installin' the motor mount. Ahoy! Ya scallywag!

 7. 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. Avast, me proud beauty!

 8. Avast, me proud beauty! Boattail. 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. Well, blow me down! Blimey! T' completed boattail should be 1" long, with one end t' diameter o' t' BT-56, t' other end BT-50. Avast, me proud beauty! Aye aye! Blimey! Glue it into shape, and when dry glue it into place. Ya scallywag! You can use thin CA or yellow glue to strengthen it. Avast! Blimey! I used a little Fill'n'Finish t' smooth t' glue joints and the seemingly inevitable minor wrinkles. Begad! Blimey! You may need t' cut a slight notch for the motor hook, me hearties, use an X-acto for this.

 9. Glue t' pairs o' tube fins around t' body on t' 1" line you marked in step 6. Well, blow me down!

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

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

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

 13. Arrr! Begad! Install t' shock cords. Begad! Well, blow me down! Glue one end o' t' 40" shock cord into t' bulkhead coupler, me hearties, me hearties, me hearties, and t' other end into t' lower body just above the baffle. 

14. Ahoy! Just for backup, glue t' last (shortest) shock cord into t' upper tube to secure t' nose cone. Aye aye! This way, matey, if t' nose cone should accidentally come loose, ya bilge rat, it'll stay attached t' t' rest o' t' rocket. Blimey!

 15. Install t' launch lugs. Arrr! I cut mine in two. Blimey! One be installed inside one o' t' tube fins (closest t' t' main body), with t' other about 12" up from t' bottom. Ahoy!

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

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

Maiden flight, 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! It climbed much quicker than I expected, arrr, me bucko, but nay a neck-snapper. 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! Begad! After-flight inspection showed that t' baffle worked perfectly, with no charrin' t' t' shock cord or chute. Aye aye!

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