Drag racing the alien interceptor

Discussion in 'Low Power Rocketry (LPR)' started by TimothyG, Nov 12, 2018.

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  1. Nov 12, 2018 #1

    TimothyG

    TimothyG

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    We are planning on doing a drag race between the two versions of the mach1rocketry alien interceptors soon still working on our launch towers Planning on 3D printed couplers with arrow shafts CA056849-2DDB-4ECF-8178-64CDE7B02288.jpeg
     
  2. Nov 19, 2018 #2

    base890

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    Can you describe the differences between the two?
     
  3. Nov 19, 2018 #3

    lowga

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    Sweet. Subscribing to this thread.
     
  4. Nov 28, 2018 #4

    TimothyG

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    So I finally got around to finishing the draw up for the 3D printed parts for the launch tower for these. Should have them printed by end of this week. The differences between the two is the green rocket is one piece tube with streamer and red rocket is the dual deployment version. We converted the dual deployment version into a breakdown single deployment type so that the student can more easily fly home to Germany with it. The rocket in broken down format fits inside a briefcase. I’ll get some pictures of the tower and the red rocket broken down in the next couple days and get them up.
     
  5. Nov 29, 2018 #5

    TimothyG

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    90094BF8-EC4E-44FF-B7FC-8128E7FA320A.jpeg This is the first draft of the parts. The top ring works fine with some tape to snug up the fit to the arrow shafts. Bottom piece unfortunately printed holes too tight for the shafts so the drawing was adjusted and a new one is printing now. The entire set up with tower, arrow shafts, rocket, and motor weighs less than a pound. I might try to launch this as a payload at some point.
     
  6. Nov 29, 2018 #6

    TimothyG

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    F7B1EEBF-A88F-4805-B07F-A7B38C0295A7.jpeg Much better on the second print. I left a fourth small hole in the bottom to nail/screw it to s board and then small twine from top to stakes to hold it down.
     
  7. Nov 30, 2018 #7

    TimothyG

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    E3206D4F-1C8A-4CD7-857A-BE6BEE146998.jpeg Twelve dollar launch tower.
     
    dhbarr and Normzilla like this.
  8. Nov 30, 2018 #8

    dhbarr

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    Make it $12.10 by epoxying a dime to the bottom for a deflector?
     
  9. Nov 30, 2018 #9

    TimothyG

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    My plan was to electro-plate the bottom piece with nickel but I like your idea way better and I can do it before this weekend much more easily. Although the bottom piece does have a dime size through hole in it that I left for exhaust gases. I honestly don't know what's best here. This is my first launch tower and I preamble to my tentative design for my L3 project tower.
     
  10. Nov 30, 2018 #10

    lowga

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    The launch tower is awesome. I'd love to purchase one of these for my own Mach 1 Alien Inceptor!
     
  11. Nov 30, 2018 #11

    TimothyG

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    I would consider it but only after I've flown it at least a few times to see what gets damaged and if anything needs improved.
     
  12. Nov 30, 2018 #12

    dhbarr

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    Oh. Then take it to the hardware store and find a piece of brass or copper adapter that fits it? :)

    Would be awesome if you post these files at some point, a tower for my 18's would be neat.
     
  13. Nov 30, 2018 #13

    TimothyG

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    I’ve never actually uploaded a file like this. What file type should I upload it as so more people can use it? I drew it up on OnShape.
     
  14. Dec 1, 2018 #14

    dhbarr

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    .stl ? I'm no expert at these things myself :)
     
  15. Dec 4, 2018 #15

    caveduck

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    Hey Timothy, easiest way is to just publish the OnShape link so people can export what they need. (from fellow OnShape user)
     
  16. Dec 4, 2018 #16

    TimothyG

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    Awesome!! Let me know if this works or not. I've never shared an OnShape file with the world before so this is new.

    https://cad.onshape.com/documents/1...aca3bf2d23f5da6189/e/36b4ee0eea4926688baf7e40


    Things I'd change.

    I don't like how loosely the rocket fits between the arrow shafts so I'd tighten that my tolerance I added there.

    It needs a middle support to prevent arrow flex from allowing the rocket to slide outwards.

    What I really wanted to do was make this a 6 arrow set up with the other three coming in from the sides as legs of sorts so that the complete assembly can stand on it's own and have clearance for exhaust gases to escape bellow. I don't know how to do that yet though so I made do with the skills I have in OnShape.

    I might create a modified top portion to put in the middle that would allow me to double the launch tower height with another three arrows.

    Aluminum arrows would be way better for this but I don't have any and they are crazy ass expensive.
     
  17. Dec 4, 2018 #17

    caveduck

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    Link works fine for me. If you right-click on one of the part studio tabs (either in left pane or at bottom) you can export as STL for printing. Inside a part, you can right-click on a sketch object to export a DXF of that.
     
  18. Dec 12, 2018 at 12:13 AM #18

    TimothyG

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    880FCD2D-CCDA-4D4E-850F-CF6CA5F642E0.jpeg We launched rockets for two hours today. Decided not to use a blast deflection device to see how the printed parts would hold up. We launched two C12 and two D20 motors with no ill effect to the plastic parts best of all the arrow shafts slide over the standard estees launch rod. I lost my alien interceptor when it left my tower slightly angled. His hit 2600 ft on the D20 motor shooting as straight and fast as I’ve ever seen a low power rocket fly. I still had a blast and I’m already planning on buying another alien interceptor to replace it . EA2474D7-6952-417D-9D77-EFD82E312FC5.jpeg
     

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