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  1. #1
    Join Date
    26th January 2010
    Location
    Northern California
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    13,159

    Make Tube Fly With Fire!

    I know I saw this name here, but can't remember who it was. If it was you, or someone you know, I'd like to give credit where credit is due.

    I've wanted to do a design like this for a while now with two body tube sizes and no transition. Originally I was working on a 4"-3" design, but downsized it to 3"-2.2". I wanted to be able to fly it on mid power G's at SARG, and small H's at Snow Ranch. I think I've succeeded. Open Rocket doesn't like the design, and keeps telling me there is discontinuity in body tube sizes. I had to do some trickery to get it to accept the fins on the lower section. I'm hoping that the stability and sims are relatively accurate. My gut feeling is stability won't be a problem, but the sims might be suspect.

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    NAR 91107, Level 2

    I really, really hate bugs.

  2. #2
    Join Date
    26th January 2010
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    I thought about going with three fins instead of five, just because of ease. Less cutting, less sanding, less fin slot cutting, less epoxying, and less masking. But in the end I decided on five fins just for the coolness factor. I've done up to six in the past, so this won't be all that bad.

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    NAR 91107, Level 2

    I really, really hate bugs.

  3. #3
    Join Date
    18th March 2012
    Location
    Oregon City. OR
    Posts
    2,548
    love the name and the design, simple and elegant.
    MOAR FYRE!
    Rob Appleton
    "That Crazy Brit"

    - - -
    Team Numb
    -exploring the possibilities-
    L3 - TRA 13815 - NAR 87999

  4. #4
    Join Date
    4th August 2011
    Location
    Lincolnton NC
    Posts
    5,332
    Kinda reminds me of my Skyjacker. 24mm cluster model with 3 motor tubes that extend around 10" from the bottom. Can't locate the nekkid pic which shows more clarity. This will have to do though. Flies really well. Can't see any reason why yours shouldn't.

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    Thinking outside the box is normal for me. Went inside the box once and got claustrophobic.
    Can't never did!
    Inventions weren't created by skeptics.
    There's a bright side to every screwed up week.


  5. #5
    Join Date
    26th January 2010
    Location
    Northern California
    Posts
    13,159
    Now that is a cool design! Love the open fins! Does it whistle? What motors have you flown it on?
    NAR 91107, Level 2

    I really, really hate bugs.

  6. #6
    Join Date
    4th August 2011
    Location
    Lincolnton NC
    Posts
    5,332
    Quote Originally Posted by qquake2k View Post
    Now that is a cool design! Love the open fins! Does it whistle? What motors have you flown it on?
    Doesn't whistle. I built it for D motors. That's all I've ever flown it with. Maiden flight was a bust though. NSL 2016 only 1 motor lit and it sharked. After the rebuild I launched it at Freedom Launch a few weeks ago. I reckon I was a bit cluster shy to fly it until recently.
    Thinking outside the box is normal for me. Went inside the box once and got claustrophobic.
    Can't never did!
    Inventions weren't created by skeptics.
    There's a bright side to every screwed up week.


  7. #7
    Join Date
    27th March 2013
    Location
    Has Changed
    Posts
    9,561
    I will be following this...
    Dreaming of making the rockets I dreamed of as a kid (and then some).


    NAR L1 Cert flight: Sheridan, Oregon, USA. Sept. 19, 2015. Flew Deep Space OFFl on an I357T-14A Blue Thunder

  8. #8
    Join Date
    19th February 2017
    Location
    The world, probably
    Posts
    466
    Quote Originally Posted by qquake2k View Post
    I know I saw this name here, but can't remember who it was. If it was you, or someone you know, I'd like to give credit where credit is due.

    I've wanted to do a design like this for a while now with two body tube sizes and no transition. Originally I was working on a 4"-3" design, but downsized it to 3"-2.2". I wanted to be able to fly it on mid power G's at SARG, and small H's at Snow Ranch. I think I've succeeded. Open Rocket doesn't like the design, and keeps telling me there is discontinuity in body tube sizes. I had to do some trickery to get it to accept the fins on the lower section. I'm hoping that the stability and sims are relatively accurate. My gut feeling is stability won't be a problem, but the sims might be suspect.
    Very cool!

    In OR, it seems to work better if you add a .001" long transition in between the sections. It should sim OK as-is, though- it just won't calculate airflow around the step.
    NAR #104043

    crmrc.org

  9. #9
    Join Date
    14th July 2015
    Location
    Randolph, NJ
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    3,233
    Quote Originally Posted by LithosphereRocketry View Post
    In OR, it seems to work better if you add a .001" long transition in between the sections.
    Yup, that's the ticket.

  10. #10
    Join Date
    15th October 2016
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    Quote Originally Posted by LithosphereRocketry View Post
    Very cool!

    In OR, it seems to work better if you add a .001" long transition in between the sections. It should sim OK as-is, though- it just won't calculate airflow around the step.
    I'm actually wondering if a near-zero length transition would cause more sim disruption than the simple tube discontinuity! Thinking of how a reducing transition will sometimes kick the CP In Front of the entire rocket without fins. May be something screwy with how it handles that geometry.

    I wholly approve of the name and the caveman decal complimenting it! Unless there were earlier usages I wasn't aware of, I used that term when discussing different rocket building approaches, Steve Shannon said he wanted it on a T-shirt, and then it got used again in the recent Drag-race rules thread.

    Build on good sir! (and I just used your zipperless baffle method in my Argent!
    "I'm at least 70% confident about whatever I say (90% of the time)"- college me

    NAR 101195
    Level 1: Big SAM, 9/10/16

  11. #11
    Join Date
    26th January 2010
    Location
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    Quote Originally Posted by Nytrunner View Post
    I'm actually wondering if a near-zero length transition would cause more sim disruption than the simple tube discontinuity! Thinking of how a reducing transition will sometimes kick the CP In Front of the entire rocket without fins. May be something screwy with how it handles that geometry.

    I wholly approve of the name and the caveman decal complimenting it! Unless there were earlier usages I wasn't aware of, I used that term when discussing different rocket building approaches, Steve Shannon said he wanted it on a T-shirt, and then it got used again in the recent Drag-race rules thread.

    Build on good sir! (and I just used your zipperless baffle method in my Argent!
    Thank you! How did the baffle work in your Argent?
    NAR 91107, Level 2

    I really, really hate bugs.

  12. #12
    Join Date
    15th October 2016
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    I honestly have no idea. Nothing caught fire that I can tell

  13. #13
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    26th January 2010
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    Got the fins cut out. 1/4" birch plywood from Michael's.
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    NAR 91107, Level 2

    I really, really hate bugs.

  14. #14
    Join Date
    26th January 2010
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    And match sanded.
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    NAR 91107, Level 2

    I really, really hate bugs.

  15. #15
    Join Date
    26th January 2010
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    Normally, I would use my miter saw to cut body tubes. But it's buried right now, by my son's camping gear. So I dug out my razor blade cutting jig.
    It worked better than I remember.
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    NAR 91107, Level 2

    I really, really hate bugs.

  16. #16
    Join Date
    26th January 2010
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    I used the jig to cut the 2.2" tube, and the bandsaw to cut the motor tube.
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    NAR 91107, Level 2

    I really, really hate bugs.

  17. #17
    Join Date
    15th October 2016
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    How do you achieve an even turn on the cutting jig?

    Any guide, or just his 'manual dexterity' technique I hear talked about?

  18. #18
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    I clamp a block to the jig to set the length. The bungee cords help hold the tube against the jig as you rotate it.
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    NAR 91107, Level 2

    I really, really hate bugs.

  19. #19
    Join Date
    26th January 2010
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    Got the centering rings cut out and sized on the lathe.
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    NAR 91107, Level 2

    I really, really hate bugs.

  20. #20
    Join Date
    26th January 2010
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    I cut out the center holes and sized them with the Dremel.
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    NAR 91107, Level 2

    I really, really hate bugs.

  21. #21
    Join Date
    26th January 2010
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    I decided to use 3/8" thick plywood for the baffle plate, since it will be smaller than usual. I drilled pilot holes all the way through, so I could drill the 1/4" holes part way from both sides. This makes the holes cleaner, with less chipping.
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    NAR 91107, Level 2

    I really, really hate bugs.

  22. #22
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    It turned out pretty good. I also started on the half moon baffles that will be epoxied into the forward end of the motor tube.
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    NAR 91107, Level 2

    I really, really hate bugs.

  23. #23
    Join Date
    26th January 2010
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    Got the rail button blocks epoxied onto the centering rings.
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    NAR 91107, Level 2

    I really, really hate bugs.

  24. #24
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    26th January 2010
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    Got the rail button blanks on the centering rings sanded. I think I need a new belt on my sander. The disc worked much better.
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    NAR 91107, Level 2

    I really, really hate bugs.

  25. #25
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    Got the half moon baffles installed in the motor tube.
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    NAR 91107, Level 2

    I really, really hate bugs.

  26. #26
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    After I had epoxied the forward centering rings onto the motor tube, I realized that I put the wrong ring on the front. So I had to put another rail button block on the aft ring. Finally, I epoxied the motor tube into the aft body tube. Next step, fins.
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    NAR 91107, Level 2

    I really, really hate bugs.

  27. #27
    Join Date
    17th December 2013
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    I'm just now stumbling onto this thread. I like it. I've been working up something similar but using tube fins instead. I'm considering minimum diameter on the business end so it can fly on soda can 54s. Torn between traditional dual deploy or JLCR. Too many other projects in the way so far.

    The caveman looks like something off of the old NES Caveman Games.
    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

  28. #28
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    That sounds like a fun project. Which 54mm motor(s) are you thinking? What size will the forward body tube be?
    NAR 91107, Level 2

    I really, really hate bugs.

  29. #29
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    26th January 2010
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    Got the fin slots cut. I vacillated between 5 and 3 fins, but in the end went with 4. I recently made a 3 fin , a 5 fin, and two 6 fin rockets, so wanted to do something different. I had to make the fin tabs a little longer.
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    NAR 91107, Level 2

    I really, really hate bugs.

  30. #30
    Join Date
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    Quote Originally Posted by qquake2k View Post
    That sounds like a fun project. Which 54mm motor(s) are you thinking? What size will the forward body tube be?
    For the tubes, I was pretty much on the same train of thought as you. 4" and 3" then went to 3" upper and 54mm lower. 18" upper, 22" lower with 16" exposed.

    If I build light enough I can fly it on the I117FJ and J90W. Long burns on a heavy drag bird should be cool to watch. Rail speed as it sims now is around 47 ft/s which will be fine. I would have to angle the rail a bit to achieve a good vertical flight. Don't really trust the sims when dealing with tube fins and that wonky transition. And I always build heavy, which is something I need to work on.

    Should fly on anything from a G to a J.

    The LOC Viper family has motor tube clusters sticking out the back of the main body tube, just no transition.

    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016
    Level 2: Binder Design Tyrannosaur ---AT J315R to 2148'--- 30 SEP 2017

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