Simple 3-stage scratch build

Discussion in 'Low Power Rocketry (LPR)' started by CoachSteve, Feb 26, 2018.

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  1. Feb 26, 2018 #1

    CoachSteve

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    straight forward build
    Bt60
    24mm booster
    18mm booster
    18mm sustainer
    should go up a ways :)

    [​IMG]
    [​IMG]
    [​IMG]
     
  2. Feb 26, 2018 #2

    BDB

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    I love it! This is the same MMT configuration as an Estes Commanche-3 (though that is BT50, I think). Three stagers like this are notorious for out of sight flights. What are you doing for recovery? I suggest streamers or an undersized parachute, unless you want to have a county-wide search area.
     
  3. Feb 27, 2018 #3

    qquake2k

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    That is such a cool design! I'd love to see it fly!
     
  4. Feb 27, 2018 #4

    CoachSteve

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    When I get out to CRASH this summer this will be one I bring for sure
    And undersized parachute is the plan :)
     
  5. Feb 27, 2018 #5

    qquake2k

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    For a light three stage, I would consider a streamer instead of a chute.
     
  6. Feb 27, 2018 #6

    CoachSteve

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    That top stage is 1.5" by 30" plus 8" nose cone - not sure a streamer will let it down safely - maybe a 2" x 5' streamer
     
  7. Feb 27, 2018 #7

    qquake2k

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    What does the sustainer weigh with a used motor?
     
  8. Feb 27, 2018 #8

    CoachSteve

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    Right at 100g
     
  9. Feb 28, 2018 #9

    LithosphereRocketry

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    That's a neat looking rocket!

    I -personally- wouldn't use a streamer on this size rocket. The ideal solution would be a Jolly Logic Chute Release- yes it will fit, just barely. I fly a 38mm rocket with it fairly frequently. If you don't have one, a small parachute should be fine.

    That said, I've had similar airframes to this fall from 1000' after the shock cord broke and be undamaged. It's up to you- some rockets fall differently than others, so use whatever works.

    By the way, I vote F44W to D21T to D10W with onboard timers. MOAR POWER! :wink:
     
  10. Feb 28, 2018 #10

    CoachSteve

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    That's a bit more than I was planning :)
    bet it would get up to a pretty good velocity - I think I am going to open rocket it to see just how insane that would be :)
     
  11. Mar 5, 2018 #11

    BABAR

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    The forward and back sweep between booster1-booster2-sustainer is cool!
    Will it go on C11-0 to A8-0 to A8-5? Will keep your staging in visual range, cut down walk to find the boosters and the sustainer.

    I might try an evil twin of yours, difference is reverse sweeps. Booster1 forward, booster2 back, sustainer forward.

    This puts a forward sweep on the sustainer. Advantage is since the sustainer lands tail first, with a forward sweep the impact point is engine casing not fin tip. Cost is fins slightly less effective (center of pressure a tad more forward with forward sweep.)

    Like your spiral tape. Is that electrical tape or something else?
     
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  12. Mar 5, 2018 #12

    CoachSteve

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    Evil twin - cool.
    The spiral is vinyl automotive pin stripe (super cheap on ebay)
    Depending on the day the first launch will be powered accordingly (super calm day this baby is going for the stars :) )
    I do enjoy seeing the deployments over sheer altitude though so i may take your advice :)
     
  13. Mar 5, 2018 #13

    Daddyisabar

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    Out at CRASH I launched several Comanche 3's D12-0 C6-0 C6-7 and have recovered all the stages. Use a long Mylar streamer/chute that glints in the sun. Good weather and a good eyes crew on the second stage is the key.
     
  14. Mar 6, 2018 #14

    BABAR

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    If you go with chute AND you have space for it in addition TO the chute, a long Mylar shiny streamer (even a thin one) can help visibility both on descent AND if it lands in bushes or tall grass, even if it is not your primary recovery device.
     
  15. Jul 8, 2019 #15

    CoachSteve

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    To the moon
     
    Last edited: Jul 8, 2019
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  16. Jul 9, 2019 #16

    jqavins

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    I'm with you there; I always like interdigitated fins. How about a not-so-evil step brother with forward swept first stage fins, rear swept sustainer fins, and second stage fins that look like a K against the body tube? Something very roughly like this:
    upload_2019-7-9_13-7-43.png
     
  17. Jul 9, 2019 #17

    BABAR

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    Very nice!
    What were motors?
    Was everything recovered intact?
     
  18. Jul 9, 2019 #18

    CoachSteve

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    D12-0 - B6-0 - B6-6

    Lost the sustainer this day - we believe it landed in the lake - I had a very small chute too - still drifted way too far -
    looks like a rebuild is in order :)
     
  19. Jul 9, 2019 #19

    jqavins

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    Too bad about the sustainer loss, but since you're smiling at the prospect of a rebuild, I guess it's not too too bad.
     
  20. Jul 9, 2019 #20

    CoachSteve

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    Ha - it was just a couple sections of tube and a nose cone - no electronics fortunately (although had i used my chute release i may have gotten it back :)
     
  21. Jul 9, 2019 #21

    BABAR

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    I see an A8-5 in your future!
     
  22. Feb 23, 2020 #22

    CoachSteve

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    So - a lost sustainer cant keep me down forever - final stage is getting a rebuild, this time a little Ram-Jet style :)
    [​IMG]
    [​IMG]
    [​IMG]

    It will fly again
     
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  23. Feb 24, 2020 #23

    mbeels

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    Nice! And a little extra drag to boot to (hopefully) keep it around for more flights.
     
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  24. Feb 24, 2020 #24

    CoachSteve

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    A little nicer weather and it will get paint and be ready for flight at CRASH this summer
     
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  25. Mar 24, 2020 #25

    CoachSteve

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    Ready to fly:
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  26. Mar 24, 2020 #26

    BABAR

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    I’m a’wonderin’ if that ramjet nose may be a bit more draggy than you think.....
     
  27. Mar 25, 2020 #27

    CoachSteve

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    I lot of drag is fine by me - as you remember, the first sustainer was lost to the cloud gods :)
     
  28. Mar 25, 2020 #28

    BABAR

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    I was thinking more stability issues. You have plenty of tail plumage, but you are also going to have a lot of mass with three motors in the tail. In the rockets favor, it is a very long rocket. It’ll proooooobaaaably do fine, definitely going to ge a heads up launch, the mid section booster is going to stage high and be hard to track.

    You gonna go full three stack on first flight, or go onesie twosie threesiee?
     
  29. Mar 25, 2020 #29

    CoachSteve

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    full stack for sure :)
    [​IMG][​IMG]
     
    Last edited: Mar 25, 2020
  30. Mar 25, 2020 #30

    BABAR

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    @neil_w would be a better source for this, but I question the reliability of ORK (or any SIM program) to calculate the CP shift from your ramjet nose.

    Also not sure of the effect of your fancy mid-body chamber on CP

    That said, due to the length of the rocket you have plenty of calibers to spare to start with, so you will probably be okay.

    Hope you get three straight trails, three short walks, and three soft landing.
     

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