First Tube Fin build 2.6

Discussion in 'Mid Power Rocketry (MPR)' started by CoachSteve, Feb 24, 2020.

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  1. Feb 24, 2020 #1

    CoachSteve

    CoachSteve

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    Ok - so maybe I bought 3 of the Rocketarium 2.6 nose cones.

    This go will be a stumpy 3 tube - tube fin design
    plans
    [​IMG]

    Fin alignment guide (a compass is your friend)
    [​IMG]

    Mock up
    [​IMG]

    Tube fin Fillet /strengtheners
    [​IMG]
    [​IMG]

    This one should net about 300ft on a D12 and well over 1000ft on a F39 :)
     
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  2. Feb 25, 2020 #2

    dhbarr

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    You have some thin CA?
     
  3. Feb 25, 2020 #3

    CoachSteve

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    I do - it wicks real nice into situations like this :)
    The top 3 inches of the body tube are "hardened" with it on the inside too (to help prevent zippering) - I do this to most all my paper rockets - really stiffens the tube
     
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  4. Feb 25, 2020 #4

    BABAR

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    I like the balsa fillets, should provide a nice combo of strength and alignment
     
  5. Feb 25, 2020 #5

    o1d_dude

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    Ah, Grasshopper, you’ve chosen the path less traveled...

    A proper tube fin rocket most commonly has 6 ( or occasionally 7 ) fins which gives each tube fin three contact surfaces for attachment and the tubes support each other.

    In spite of this, tube fins still occasionally break or break off in the landing.

    “Salami” slicing the bottom of the tube fins can help by reducing the moment arm at impact and also reduce the normal landing damage to the outside edges of the tubes. ( Tube fin rockets NEVER stick the landing. )

    BTW, CA glue is very brittle but epoxy has a bit of flex. Just saying.

    You could also cut extra tube fins in half lengthwise and laminate them inside the tube fins with epoxy for extra strength in the manner of doublers.

    Here’s one of mine in action last week. Note how short the tube fins are. This was an attempt to fool with the aspect ratio and produce a very straight boost with minimum drag. Mostly successful. 3” diameter tubing used for body and fins. Boost is on G77R and aimed away from downwind pond. Has flown on H165R motors also ( 18G’s off the pad! ). Red motors for red rockets, right? Multiple repairs to fins over the years but it keeps on going.

    In spite of all these idiosyncrasies, tube fin rockets are cool and draw a lot of comments.

    79F94F58-44F1-4A80-84B7-3A3C00B31EBB.jpeg
     
  6. Feb 25, 2020 #6

    CoachSteve

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    I will report back for sure on how well my "gusseted" tubes hold on :)
    first flight will be a modest D12-3 just to see how it all goes. If all goes well this one will get the full F39 treatment.
    But, as I never fly my rockets naked, next step is finishing - stay tuned :)
     
  7. Feb 25, 2020 #7

    neil_w

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    Salami slicing?
     
  8. Feb 25, 2020 #8

    CoachSteve

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    I believe that's where you cut the bottom of the tube fin upwards at an angle - like up swept fins. That way the outermost edge of the tube fin doesn't contact the ground first :)
     
    Last edited: Feb 25, 2020
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  9. Feb 25, 2020 #9

    neil_w

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    Oh, just miter-cutting, yeah got it.
     
  10. Mar 4, 2020 #10

    CoachSteve

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    Getting some paint - I will post picts later today
     
  11. Mar 4, 2020 #11

    BABAR

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    This guy sounds like the Tube Guru. Here is his home page on RocketReviews

    https://www.rocketreviews.com/larry-brand-page.html

    I think he has demonstrated that 7 tubes is the optimal aerodynamic orientation, although it is a little hard to achieve. 6 tubes, with the tubes the same as the main body tube diameter, is by far the easiest to construct.
     
  12. Mar 4, 2020 #12

    dhbarr

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    Some really great magazine articles, as well. LBWR is my 29mm MD 7x1 tuber.
     
  13. Mar 4, 2020 #13

    o1d_dude

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    Larry Brand is the man.

    Most of my tube fin rockets are based on his designs.
     
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  14. Mar 4, 2020 #14

    CoachSteve

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    Where's Waldo
    [​IMG]
     
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  15. Mar 5, 2020 #15

    BABAR

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    Ironically, should make it EASY to find on most rocket launch sites!
     
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  16. Mar 5, 2020 #16

    CoachSteve

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  17. Mar 21, 2020 #17

    jqavins

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    Wha'd'ya mean "where's Waldo"? He's right there on your air hockey table getting his picture taken!
     
  18. Mar 21, 2020 #18

    CoachSteve

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    It just seemed like the appropriate paint scheme for a rocket with this shape :)
     
  19. Mar 23, 2020 #19

    Donnager

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    Scary sock puppet monkeys come to mind as well.

    Love the paint job.
     
  20. Mar 23, 2020 #20

    BABAR

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    Next time try spiral stripes done with colored electrical tape. you can use it to cover the spirals!
     
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  21. Mar 23, 2020 #21

    CoachSteve

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