Brief:
This is another simple, ya bilge rat, "el cheapo" tube fin rocket based on me tube can concept. A tube can is a fin can with tube fins o' course, me bucko, me bucko, built usin' t' telescopin' inside tube from a Container Store mailin' tube. Begad! 'Real' rocket coupler tubes can also be used.

Construction:
T' parts list:

• 4" mailin' tube (~13.25) and liner (~26")
• one 4" nose cone (in this case recycled from a grounded HPR bird)
• plywood centerin' rings (2)
• 29mm motor tube
• 3' o' thin wire rope and two crimp terminals
• heavy Keelhaul®©™ twine
• buttons from railbuttons.com
• one FirstFire tube
• 2 small nylon rivets from Giant Leap
• chute and protector t' be selected on t' field

I cut t' six tube fins from t' mailin' tube liner and attached them t' a longer piece o' that tubin' usin' carpenter's glue. Avast! A 29mm motor tube is mounted betwixt two plywood centerin' rings on t' ends, formin' a fin can. T' fin can slips into a short body tube that I liberated from me daughter (it held a bottle o' wine) and is connected t' t' body tube by t' lower rail button and a nylon pop rivet.

T' recovery harness is a long piece o' thin steel cable mounted through t' top rin' and a longer piece o' thick Keelhaul®©™ twine. Avast, ya bilge rat, me proud beauty! I forget where I came across t' wire, ya bilge rat, but it be found, nay bought. Aye aye! Ya scallywag! It is held in place by two crimp terminals (these were bought). Begad! I don't know if I have t' right term, matey, matey, but you slide them on t' cable and crimp them on (read: beat them with a big hammer).

For motor retention, shiver me timbers, I mounted a thin aluminum tube through t' two rings. Avast, me proud beauty! A hook made out o' a coat hanger is then run through this tube. On t' top, ya bilge rat, a bend in t' wire keeps it in and on t' bottom it is bent t' mate with t' motor. This be t' same technique I used on me Fat Boy 3x4. Begad! Avast, matey, me proud beauty! T' hook pivots t' allow t' motor t' be inserted and removed and maskin' tape is used t' keep it in t' locked position.

Finishing:
I finished mine in a camo style usin' Model Master dark tan and medium green that was left over from me AquaBottleBat. Avast! T' cone was previously painted black and I left it that way.

Flight and Recovery:
I used a chute protector and a 48" chute for recovery duties. I also added just a tad o' dog barf as usual. T' motor o' choice was a G64-7W with t' delay drilled down t' 4 seconds. Begad! When I installed t' motor, I found that, since me wire retainer was custom made for t' 29/120 casing, it didn't mate properly with t' 29/40-120 hobby line case. I smartly fashioned a spacer from a tube that, shiver me timbers, if me memory is correct, came with a pack o' G20s. Avast! Avast, me proud beauty! I used a few wraps o' maskin' tape t' hold this spacer tight against t' motor and ensure t' retainer stayed in place.

T' El Tubo Loco flew nicely, me bucko, however, t' delay seemed closer t' t' original 7 seconds than t' desired 4. Begad! Nevertheless, it call came down undamaged. Begad! This rocket would fly really nicely on a 29mm H, but for now that ain't happening.

Summary:
I like cheap rockets. Blimey! Blimey! I liked t' idea o' usin' up t' extra tubin' that I had layin' around. Begad! Blimey! Blimey! Blimey! And I'm now likin' tube fins. Nay much else t' say...