Quark 18mm upscale (BT-5 to BT-20)

Discussion in 'Low Power Rocketry (LPR)' started by JonathanOtt, Apr 20, 2019.

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  1. Apr 20, 2019 #1

    JonathanOtt

    JonathanOtt

    JonathanOtt

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    I picked up an Estes Hi-Flier return at Hobby Lobby a few months ago. It's missing a few parts (the ones you really need) but there is enough left to play with (BT, find, sitckers, nose cone, shock cord, streamer), but no engine hook, no motor block, no end cap for the nosecone...but who ever returned it did leave the two multi-language warranty trifolds. o_O

    Anyway, I thought I'd do a Quark upscale. The multiplication factor is 1.36 so now I need fin dimensions. I have a PDF of the Quark instructions (attached), can someone (who's awake at this hour) give me the actual measurements of the fins on the PDF? I'll do the math (it's not that late). I'm working off my phone right now, and it's impossible to any measurement on that PDF with any degree of accuracy.

    Thanks!!!
     

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  2. Apr 20, 2019 #2

    GlenP

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  3. Apr 20, 2019 #3

    JonathanOtt

    JonathanOtt

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    Thanks Glen.

    Okay, I adjusted the image on my phone to show the fin width as 1/2" wide, then measured the parallelogram and come up with a long edge of 49mm, short edge 21mm, over all length of 72mm.

    This should give me a fairly accurate template.
     
  4. Apr 21, 2019 #4

    BABAR

    BABAR

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    Quark original is featherweight recovery.
    I believe essentially that means engine eject and it comes in ballistic but since it is so light it is considered safe.

    Upscaling it, yours will come down with a bit more kinetic energy.

    Giving it is a very short rocket not sure you have room for a streamer. You could however consider simple nose blow recovery. With this the rocket will be unstable and will tumble recover
     
  5. Apr 21, 2019 #5

    BABAR

    BABAR

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    Use the lowest thrust 18 mm engine you can find. Or get adapter and fly it on an A10-3T
     
  6. Apr 21, 2019 #6

    JonathanOtt

    JonathanOtt

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    Yeah, it'll be nose blow. Scaling it up 1.38 makes the BT almost exactly the same length as a 18mm motor. Add .5" for the nose cone shoulder and the motor sticks out the same at the aft end.

    I don't have any 18mm motors here, how deep it the recess to the clay plug on the front end of the motor.

    I'm leaving the end cap off the NC, so I'll have someplace to put the kevlar shock cord...how much do you think, 'bout 24"?
     
    Last edited: Apr 22, 2019
  7. Apr 22, 2019 #7

    BABAR

    BABAR

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    Some may frown on this but ideal recovery would be combined nose cone AND motor eject. Priority is a VERY LOOSE nose cone, as you don't want a ballistic recovery with motor in place. Then load motor "loose" (you will have an engine block so it won't go forward)

    Hope is that ejection charge will BOTH deploy nose AND kick the motor. The nose cone and rocket body will very lightly tumble. May save your fins.
     
  8. Apr 22, 2019 #8

    JonathanOtt

    JonathanOtt

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    Sounds like a reasonable idea.
     

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