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Thread: Bluefin Tuba

  1. #1
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    Bluefin Tuba

    Update 2014-06-22: this rocket has now flown on motors from E16 to J510, 6 impulse classes. at 1,162NS and 23", J510 is the largest-impulse certified 38mm motor that is commonly available. Bluefin Tuba can now officially take any motor that fits in the fuselage.

    ============================

    I'm building a minimalistic 38mm MD tube-fin rocket out of Blue Tube. If you think the name is a bad pun, I challenge you to come up with a better one!

    I've had a lot of fun with PVC and ABS tube-fins. My 2 3/8" ABS Black Piper flew on everything from F50 to J575. It has sadly met with a non-performing delay on the J575 and lake-staked at BALLS. Gary was kind enough to replace the reload, and now I need a new simple, motor-eject tube-fin to replace that one.

    As with Black Piper, my goal is to find how far I can push a basic tube fin design without reinforcing it. Bluefin Tuba is lighter and less draggy than Black Piper and simulates surprisingly well on motors as small as E15 (OR predicts 600' feet). I'm looking forward to HPR season finally starting in NorCal to see how it performs on larger motors.

    Construction is super basic. I use a miter saw with plywood (180-tooth) blade to cut 2" fins off a 48" standard piece of BT. I use the entire remaining 35 1/4" for fuselage.

    Even this fine-tooth blade produces fuzz, which I clean up with a knife in the inside and 80-grit on the outside. I like to orient my knife along the fibers in BT winds to avoid digging in.

    I sand off 3 stripes on each fin about 30˚ apart. On the BT I simply sand an entire band instead of trying to measure off 6 separate stripes.

    I use yellow glue on BT. I apply it in slightly more liberal quantity than usual, so that it makes a fillet when it dries. Glue lines are visible in the last shot. Once yellow glue is dry, I make a second-layer fillet with Titebond Molding glue. I assemble my tube-fins in 3 sub-assemblies which I let dry before continuing on. I find it the easiest to keep all fins in alignment this way.

    Ari.

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    Last edited by iter; 23rd June 2014 at 07:15 PM. Reason: spelling
    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

  2. #2
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    I like the name.


  3. #3
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    Yes, the name is great. Keep it.

    NAR# 94191 L1
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    Level 1 Cert. flight on a Pem Tech King Kraken Jan. 5, 2013
    Videos of my launches can be found here.
    Hamming it up as W7RAB

  4. #4
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    You've pretty much laid out process I use for building my tube fin rockets.

    The three subassembly method allows you to apply some serious fillets in places that will be inaccessible once assembled.

    I also sand the boby tube where the tube fin assemblies will be attached.

    Looking forward to see this bad boy fly, Ari.

    via Forumrunner/GS4
    Cranky Kong, Certified Rocket Monkey
    "But we were promised jet packs!"

    Total Impulse in 2017: 605.77 Ns (Equivalent to an 89% I motor)
    Total Impulse since 2010: 13,872.11 Ns (Equivalent to a 35% N motor)

  5. #5
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    Yes very cool , I love your builds and not doing the norm . Very out of the box and it works . I'm doing a six tube fin rocket about 3' tall with 1.5' fins for a evil minon up scale that we did . It going to be 54mm about 10lbs ( 4.25" carrpet tube )
    Recertification coming soon
    Member of Indiana rocketry joining again

    Tripoli 14704 L2
    L1 mwp 11 XS on a H 250
    L2 mega Hi flyer on J285
    Staring my L3 build a 10" sono tube fin 10.50' tall



    I scratch build .

  6. #6
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    You can use wood glue on Blue Tube? I didn't know that... Now that I know, I really want to try out the stuff (Blue Tube that is)... Maybe for a High Power version of my first MPR scratch build...
    CAR S 1096 Level 3 | My YouTube channel
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  7. #7
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    Is this 38mm or 29mm?

    Please tell me you're going to put the largest motor possible in it...
    Several rocket motors burned this year.

  8. #8
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    Quote Originally Posted by iter View Post
    If you think the name is a bad pun, I challenge you to come up with a better one!
    awesome pun/name!

  9. #9
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    Quote Originally Posted by CarVac View Post
    Is this 38mm or 29mm?

    Please tell me you're going to put the largest motor possible in it...

    Read the first line in the first post...
    CAR S 1096 Level 3 | My YouTube channel
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  10. #10
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    You know, an I1299/I600 would do a number on it...
    Matt, Tripoli #14257
    L1 11/13/16
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    L3 Spring 2018....
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  11. #11
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    Quote Originally Posted by iter View Post
    If you think the name is a bad pun, I challenge you to come up with a better one!
    I was always told, " you can't tune a tuba, but you can tune a fish"

    Nice name.

    Bryce Chanes
    Previous ROC Board Member
    NAR 89467, TRA 13928 L3
    KR0CKT General
    Follow me on: YouTube, Twitter, Google+, Facebook

    2011: 14,773Ns (44% N)
    2012: 38,670Ns (89% O)
    2013: 26,936Ns (32%O)
    2014: 7,392Ns (45%M)

    www.BryceChanes.com

  12. #12
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    Looking forward to following this build of yours Ari. I'm a bit surprised Leah wasn't in any of your first pics. I'm assuming she's helping you out. I enjoy the fact that you look to build things that can fly a variety of motors.
    Russell Westergaard
    NAR #93881
    L1 G-Force on an H-340
    L2 Mizz Rhonda on an J430
    Woosh Nar section 558

  13. #13
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    Quote Originally Posted by bandman444 View Post
    I was always told, " you can't tune a tuba, but you can tune a fish"

    Nice name.
    Ouch! You really need to "roll with the changes" to get over that one. I think it's "time for me to fly" before you start "runnin' blind" and "blazin' your own trail again".
    Jeff Vegh
    TRA# 03011
    NAR# 92403

  14. #14
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    Quote Originally Posted by rocketgeek101 View Post
    Read the first line in the first post...
    I read every line but that one three times...wow.

    IT'S J510 TIME
    Several rocket motors burned this year.

  15. #15
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    This is cool! It's very similar to a project I've wanted to do for a long time, but don't have the money for; make a minimum-mass 38mm minimum-diameter tube fin rocket and fly it supersonic... =p

  16. #16
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    Quote Originally Posted by CCotner View Post
    This is cool! It's very similar to a project I've wanted to do for a long time, but don't have the money for; make a minimum-mass 38mm minimum-diameter tube fin rocket and fly it supersonic... =p
    Ummmm...tubefin rockets don't do Mach so well. Lotta drag and some other mysterious factors come into play.

    via Forumrunner/GS4
    Cranky Kong, Certified Rocket Monkey
    "But we were promised jet packs!"

    Total Impulse in 2017: 605.77 Ns (Equivalent to an 89% I motor)
    Total Impulse since 2010: 13,872.11 Ns (Equivalent to a 35% N motor)

  17. #17
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    Quote Originally Posted by CarVac View Post
    Is this 38mm or 29mm?

    Please tell me you're going to put the largest motor possible in it...
    According to OR, the smallest 38mm motor puts this over 1,600', which is above the 1,000' ceiling we have at Moffett. I am going to have to adapt down to 29 or even 24mm (E15 sims to 633'). I'm toying with installing an Aeropack retainer and using their adapters, but where I feel this back-to-basics project wants to go is tape retention. I'm planning a simple cardboard 29-to-38 adapter.
    Quote Originally Posted by blackbrandt View Post
    You know, an I1299/I600 would do a number on it...
    You're thinking small. Carlo has the right idea.
    Quote Originally Posted by CarVac View Post
    IT'S J510 TIME
    Funny you should mention that. Along with my replacement J575, I have a J510 left over from the how-hard-can-I-push-a-plastic-rocket project. I've had ejection failures with that one but never any aerodynamic stress issues. Apropos of nothing.
    Quote Originally Posted by o1d_dude View Post
    Ummmm...tubefin rockets don't do Mach so well. Lotta drag and some other mysterious factors come into play.
    It appears next to impossible to push a tube-fin though Mach. As you say, the drag goes up non-lineraly and wants to tear fins off. Shock wave propagates into fin tubes and makes them produce as much drag as if they were solid cylinders. Now the question becomes, can the fins stay on? They stayed right where I glued them on the ABS rocket on J575. BT may be slightly flimsier than ABS, then again Titebond may grip better than ABS cement. To put things in perspective: in the steady state, where the rocket has accelerated to almost Mach 1 and thrust produces no additional acceleration, a J510 puts out 150 lbs of thrust. Between the fuselage and 6 fins, this works out to just over 20 lbs a tube. I make no predictions, but the numbers look less scary this way.

    Now I've seen an M2200 (or M3000?) shred the fins off a 6" Kraken. This is significantly more thrust per much thinner fin. 6" BT is about as thick as 38mm, but with 4 times the circumference. Kraken has 4 fins, meaning each has a single connection point to fuselage--unlike the 6-pack arrangement where each fin supports the two next to it. Again, no predictions, just trying to convince myself I'm sane.

    Ari.
    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

  18. #18
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    Quote Originally Posted by Rrwjr View Post
    Looking forward to following this build of yours Ari. I'm a bit surprised Leah wasn't in any of your first pics. I'm assuming she's helping you out. I enjoy the fact that you look to build things that can fly a variety of motors.
    Co-parenting is hard. Schedules are hard. I have her this weekend--looking forward to her help painting the fuse when she wakes up.

    Thank you for your encouragement. I like to have a go-to rocket that I can fly at our year-round Moffett launches (LPR, 1,000' ceiling) as well as at our less reliable winter HPR launches.

    Ari.
    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

  19. #19
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    We masked the rocket and shot one layer of white. With the weather as cold as it is, it was time for Leah to go to her mother's before that first coat was dry. Co-parenting is hard.

    I like especially the Excalibur-wielding picture. We taped a piece of 1.5" dowel inside the rocket as a handle for painting, and the pose just sort of happened.

    Ari.
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    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

  20. #20
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    I think it's great you little girl helping . Mine loves to help me . I know one day she will have me help here
    Recertification coming soon
    Member of Indiana rocketry joining again

    Tripoli 14704 L2
    L1 mwp 11 XS on a H 250
    L2 mega Hi flyer on J285
    Staring my L3 build a 10" sono tube fin 10.50' tall



    I scratch build .

  21. #21
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    Progress over the last week or so.

    After second coat of white and removing the mask.
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    Molding glue fillets and what they look like when they dry.
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    This glue is very thick. It tends to leave air gaps. I use a sharp wooden stick to push the glue in and bubbles out. Third photo shows the fillet after it dries.
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    After the fillets dry on each side of each sub-assembly, I glue the outriggers on one at a time. It's harder to use clothpins or c-clamps at this stage, but the good news is that the structure is self-aligning at this stage.Simple rubber bands hold everything in place until the glue dries.
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    Ari.
    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

  22. #22
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    Great documentation!
    Several rocket motors burned this year.

  23. #23
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    Leah is mastering the drill press.

    A #8x32 machine screw holds both the top rail button and the recovery train. It is high enough from the bottom to allow a full 38/1320 case should insanity strike. I'm still working out the details of lower rail button installation: I cannot drill through MD body tube, and I need sufficient standoff for rail to clear the fin it's passing though. A part of me wants to omit the lower button all together. A 1010 rail is a snug enough fit in a 1.5" fin that I may just leave it as is. It's like the hugest launch lug evar.

    Ari.
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    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

  24. #24
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    Very nice! I think that one of my next rockets will have tube fins.
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  25. #25
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    Quote Originally Posted by iter View Post
    Leah is mastering the drill press. A #8x32 machine screw holds both the top rail button and the recovery train. It is high enough from the bottom to allow a full 38/1320 case should insanity strike. I'm still working out the details of lower rail button installation: I cannot drill through MD body tube, and I need sufficient standoff for rail to clear the fin it's passing though. A part of me wants to omit the lower button all together. A 1010 rail is a snug enough fit in a 1.5" fin that I may just leave it as is. It's like the hugest launch lug evar. Ari.
    Glad to see you got some time with your helper. Clever idea on the tube fin instead of a button down low. I think that would work if your that close to rail size.
    Russell Westergaard
    NAR #93881
    L1 G-Force on an H-340
    L2 Mizz Rhonda on an J430
    Woosh Nar section 558

  26. #26
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    Nice to have moments like that, worth a million bucks.
    Quote Originally Posted by iter View Post
    Leah is mastering the drill press.

    A #8x32 machine screw holds both the top rail button and the recovery train. It is high enough from the bottom to allow a full 38/1320 case should insanity strike. I'm still working out the details of lower rail button installation: I cannot drill through MD body tube, and I need sufficient standoff for rail to clear the fin it's passing though. A part of me wants to omit the lower button all together. A 1010 rail is a snug enough fit in a 1.5" fin that I may just leave it as is. It's like the hugest launch lug evar.

    Ari.
    Lance
    NAR # 95771
    L1 2/9/13
    ROC Club Member

  27. #27
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    Finishing touches ahead of tomorrow's flight.

    LOC nosecones come with fragile plastic loops. I like to drill a pair of holes and thread paracord though them.

    Moffett has a 1,000' ceiling. Even the smallest 1-grain 38mm motors put BFT over that limit. In keeping with back-to-basics aesthetic, I make a ghetto 29-to-38 adapter out of a piece of BT and two CRs.


    Thank you to all of you for your encouragement regarding Leah. She is very dear.

    Ari.
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    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

  28. #28
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    I use parrcord for nose cones as well . Yes love my little girl help me on my builds . Think I will make her a strong woman one day , and maybe she will start building makes me proud .
    Recertification coming soon
    Member of Indiana rocketry joining again

    Tripoli 14704 L2
    L1 mwp 11 XS on a H 250
    L2 mega Hi flyer on J285
    Staring my L3 build a 10" sono tube fin 10.50' tall



    I scratch build .

  29. #29
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    I have made the hole in the center a little larger to have access. I then fish the para chord in from the sides of the 2 holes and make the ends come out the center hole. Then tie the knot, pull it back into the cone, then all you have "outside" of the cone is para chord, not the knot.
    Quote Originally Posted by iter View Post
    Finishing touches ahead of tomorrow's flight.

    LOC nosecones come with fragile plastic loops. I like to drill a pair of holes and thread paracord though them.

    Moffett has a 1,000' ceiling. Even the smallest 1-grain 38mm motors put BFT over that limit. In keeping with back-to-basics aesthetic, I make a ghetto 29-to-38 adapter out of a piece of BT and two CRs.


    Thank you to all of you for your encouragement regarding Leah. She is very dear.

    Ari.
    Lance
    NAR # 95771
    L1 2/9/13
    ROC Club Member

  30. #30
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    Quote Originally Posted by accpool View Post
    I have made the hole in the center a little larger to have access. I then fish the para chord in from the sides of the 2 holes and make the ends come out the center hole. Then tie the knot, pull it back into the cone, then all you have "outside" of the cone is para chord, not the knot.
    I like this idea. It may be easier on larger NCs where I can drill larger holes.

    BFT flew today on an F50-4, I'd say about 800'-900'. Ejection timing is near-perfect. Sadly, all I have is a post-flight photo, but I like it nonetheless :=)

    Ari.

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    2013 41,122Ns; 2014 27,030Ns; 2015 23,202Ns; 2016 16,474Ns

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