Build Thread: Office Supply Rocket

Discussion in 'Scratch Built' started by jqavins, Aug 15, 2019.

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  1. Sep 3, 2019 #91

    jqavins

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    Joseph Avins TRF Supporter

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    No, there's a spend motor in place. The MMT came out rather flimsy. For launch, it needs to transfer force from the engine block to the centering rings, which means it will be in tension, and it will be fine that way. But against a side load it will squish very easily, so I keep an engine it is for support. I followed what I understand to be the normal instructions for rolling a tube, and I expected a stronger result. It will do.
     
  2. Sep 3, 2019 #92

    BABAR

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    Hmmmm..... it’s gonna come down fast. Maybe an external shock cord attachment so it comes down sideways, mounted at rocket body CG post motor burn outs, like a competition streamer rocket?
     
  3. Sep 3, 2019 #93

    neil_w

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    What does it weigh?
     
  4. Sep 3, 2019 #94

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    Joseph Avins TRF Supporter

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    Umm, I ought to know that, shouldn't I?

    The field at MARS launches is grassy and soft. I'll bet the same is true or RadRock's site, given the area's lush flora in general.
     
  5. Sep 3, 2019 #95

    neil_w

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    Yeah, the RadRock site is mostly soft, sometimes liquidy, and only very occasionally pavement.
     
  6. Sep 4, 2019 #96

    jqavins

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    Joseph Avins TRF Supporter

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    170 grams, including a spent E12. Yeah, it's heavy for streamers, even my three streamer arrangement. As I said, I'll just have to trust to the rocket's toughness and turf landings.

    After posting yesterday about the bag parachute option I remembered something else I had thought earlier. I might use one of the plastic bags they line trash cans with, but where would I get shroud lines? Shrouds are supposed to be light and small to pack, so rubber bands (even cut open into rubber strings) don't seem like a good idea, and I've got nothing else.

    So it is what it is.
     
  7. Sep 4, 2019 #97

    neil_w

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    Shroud lines are a stumper. I'm looking around here and coming up empty.

    Was wondering if it's possible to fashion something that is simply more draggy than a streamer, but that attaches directly to your rubber band shock cord. You don't have a shortage of space inside for something a little more bulky, but I'm not having any great ideas about what that would be.

    [addendum] Just looked in the supply closet here, and really rubber bands are the only thing I can come up with. Would it be worth cobbling together a 4-line chute, using cut rubber bands as shroud lines? Even if they're short, the whole thing could still offer more drag than a streamer (I think), and weight shouldn't be too bad. That is, if you feel that you need to improve on the 3-streamer strategy, which is your call.
     
    Last edited: Sep 4, 2019
  8. Sep 4, 2019 #98

    jqavins

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    It may be that a single really big streamer, like a whole waste basket liner, would be better than my three small streamers.

    Maybe I've got it. With the same number of rubber bands, reconfigure so that for two band's length there are two in parallel. I could use the two ends of that section and the two midpoints of that section to make four attachments to a bag. That would make sort of a shroudless parachute. Lame as parachutes go, but probably better than what I've got. And if it doesn't work, it's still a very big streamer.

    Hmm, I'll have to think about that.
     
  9. Sep 4, 2019 #99

    BABAR

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    I was thinking wastebasket garbage can liners would be considered legitimate office space items .

    Not sure how much room you have for packing and wadding but if you can attach 4 streamers you can attach your Square parachute at the end of the streamers and have the best of both worlds .

    Sometimes packing tapes are reinforced with threads within them. A thin streamer with packing tape on one side (to cover the sticky side) could possibly make a decent although bulky shroud line .

    If your simulation can handle it if the motor sticks out a bit on the back and the rocket comes down vertically tail 1st the motor mount will take the brunt of the impact. Although if your motor mount is flimsy that may not be the best approach!
     
  10. Sep 4, 2019 #100

    jqavins

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    The motor does stick out, and the motor mount seems fine when there's a motor in it. All this is why I'm on the fence about trying to make a parachute. While streamers are certainly unusual at this weight, I still think the rocket will survive, particularly (as said twice already) on a turf field. If I still lived in the California desert it would be a different story.
     
  11. Sep 4, 2019 #101

    neil_w

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    Important distinction.

    Likewise, my builds and paint jobs and recovery systems are designed expressly for the soft landing fields I fly. I would not fly many of my rockets on the playa for instance, or if I did I would be putting in much bigger parachutes.
     
  12. Sep 4, 2019 #102

    BABAR

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    On the good side, assuming a straight up trajectory , you will have a short walk!
     
  13. Sep 5, 2019 #103

    jqavins

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    Posing with the rest of the "fleet".
    20190905_080831.jpg
     
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  14. Sep 5, 2019 #104

    mbeels

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    Nice, is that a spent motor casing stand? Good idea.
     
  15. Sep 5, 2019 #105

    jqavins

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    Joseph Avins TRF Supporter

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    Yup. Just one of the thousand uses for those. It's not a beautiful display stand, but it's just fine for standing storage, painting, etc. I try to keep enough to store my rockets plus a couple more around. And if one is damaged it's no serious loss.
     
  16. Sep 5, 2019 #106

    neil_w

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    I keep all of mine, which is... too many.
     
  17. Sep 5, 2019 #107

    mbeels

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    All of your used motor casings? Wow.
     
  18. Sep 5, 2019 #108

    neil_w

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    I don't fly that much, so it's not as bad as you might envision. ;)

    Never sure how many is "enough" to keep around. Probably should go and dump some.
     
  19. Sep 5, 2019 #109

    jqavins

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    I was talking about how many cheap and dirty stands I like to have around. I keep a good few more spend motors than that.
     
  20. Sep 6, 2019 #110

    jqavins

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    Time for a quick lessons learned post. What would I do better if I do this again?
    • First and foremost, I'd machine or 3D print a form for the nose cone. The glue, fold, glue, fold, and open method I used gave me a decently strong and stiff feeling product, but the glue made the paper somewhat floppy and I couldn't get the shape neat. Next time I'll have a form to press it onto once it's opened up so it holds its shape while the glue dries. Possibly even a matched form and die, but that would keep the glue from drying in a timely manner if it's any sort of PVA glue again. (And it would be if it's another office supply rocket. Using the technique for something else then I could do it with epoxy, which would cure fine closed between the two pieces.)
    • Dress the tube ends before assembly. The reason the tube joint was so bad to start is that the ends are messed up by their use in a dispenser. I should have sanded them neat.
    • I'll try mixing my home made filler in different consistencies using different ratios of dust, water, and glue. (There was no water this time.) I might then be able to fill the spiral grooves as well as the tube joint.
    • I'm not sure about the tape on the fin edges. It's already peeling in places. I might paper over them instead, but then the use of tape shows off another office supply. Maybe I can justify wider tape (like clear packing tape) as an office supply, which would work much better than the 'regular' 3/4" wide tape I used this time.
    • I should have found a way to incorporate business cards. What's an office craft project without business cards?
     
  21. Sep 15, 2019 #111

    jqavins

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    Well, it had its maiden flight on 9/14 and its second flight on 9/15, both on D12s, and both successful. There was very, very minor damage in the first flight - I had to replace two of the three streamers - and the second was flawless.

    Can you build a rocket out of only stuff scrounged in the office and then fly it successfully? Yes. Yes you can.
     
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  22. Sep 15, 2019 #112

    BABAR

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    Congrats! There’s a lot of satisfaction in accomplishing a successful mission from that level of “scratch”
     
  23. Sep 15, 2019 #113

    neil_w

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    Glad to hear it flew again successfully! The flight on Saturday was really extremely clean, just a bit of rotation going up (hardly surprising) but pretty much straight up and perfect deployment.
     
  24. Sep 16, 2019 #114

    mbeels

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    P9140704.JPG

    Somehow, l missed the significance of launching the Office Supply rocket next to a pencil rocket. But it seems auspicious.
     
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  25. Sep 16, 2019 #115

    neil_w

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    Good observation! :)
     
  26. Sep 16, 2019 #116

    jqavins

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    Joseph Avins TRF Supporter

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    LOL :)
     

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