Mean Machine - Mid separation

Discussion in 'Low Power Rocketry (LPR)' started by beantownJPL, Sep 18, 2019.

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  1. Sep 24, 2019 #31

    BBowmaster

    BBowmaster

    BBowmaster

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    Nope. I just noted that a very healthy lung capacity could exceed the force of a normal ejection charge.
     
  2. Sep 24, 2019 #32

    beantownJPL

    beantownJPL

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    I hope my joke was taken in spirit...

    I did not feel any real resistance when I gave it the "puff" test, I'm fairly certain that the ejection charge from a 24mm motor would produce a much stronger (and steeper) pressure spike than I did with my test. Considering that in a stock build, the ejection charge must pressurize more than double the volume and manages to pop the cork reliably, I'm confident that it'll have no problem at all ejecting this setup reliably.

    While I do have healthy lungs, I'm by no means above average in lung capacity. I'm pretty sure an emphysemic pack-a-day smoker could achieve a similar result. :D
     
  3. Sep 28, 2019 #33

    Joshua Westbrook

    Joshua Westbrook

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    Got mine together today! Built this one the normal way, if I do another I'll try the mid separation suggestions on here.
     

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  4. Sep 28, 2019 #34

    beantownJPL

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    I started working on primer coat for mine tonight. Didn't take any photos though.

    Your's looks good. These things are fun to fly.
     
  5. Sep 28, 2019 #35

    Joshua Westbrook

    Joshua Westbrook

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    I've got to primer my cherokee as well so that's my plan for tomorrow.
     
  6. Oct 8, 2019 #36

    beantownJPL

    beantownJPL

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    Maidened the mid-break Mean Machine (dubbed Mean Machine Mk. II) this past saturday at the club launch.

    The first launch on a D12-3. Launch and ejection were textbook, however the chutes fouled because I wasn't careful enough with my packing and/or loose ends on the shock cord. Both chutes were properly ejected, but didn't deploy well due to tangling issues. Landing was "rough", but the only damage were some mud on the nose cone and fins.



    A later launch utilized an Aerotech E20-4T. I had addressed the fouling issues and this launch was flawless. Apogee was probably in the 800' range, and ejection was probably a bit early ... but the airframe didn't suffer from it. Video suffers from being directly in the sun, but recovery was textbook. Touchdown within 100' of the pad.



    I flew this rocket once on a D12-3 (vid 1), twice on E20-4T (vid 2), and once a E12-6 (not shown). It flies absolutely awesome, and the mid-separation, dual-chutes is a real crowd pleaser and I got comments and questions from other rocketeers on each launch.

    Every deploy was flawless. The first launch where the chutes didn't inflate properly was operator error ... the shroud lines tangled in the shock cord knots. Easily addressed by applying a couple wraps of tape to hold down the "tag end" of the shock cord knot. Once rectified, the following launches had no recovery issues.

    It's pretty cool to watch the two parts of the rocket sail apart from one-another as the laundry unfurls. They get 20 - 30 feet apart before the canopies inflate, and then they come down pretty much together as they drift in the breeze.
     
    Last edited: Oct 8, 2019
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