Piston question?

Discussion in 'Techniques' started by AfterBurners, May 23, 2019.

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  1. May 23, 2019 #1

    AfterBurners

    AfterBurners

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    I have a Sumo and as you know it comes with an ejection pistion instead of nomex chute protector and the same goes for my PML kit.

    I had a Sumo previously until it took a core sample on its second flight. Ouch. I would like to build this kit stock with the piston. I still have the one from the previous kit and fits great. I sanded and primered it. For those of you who used piston ejection do you primer the piston or just leave the card board finish? I felt if I primered it, it would provide protection and a smoother surface so it fits and slides out better.

    On PML kit I assume it best to leave it in Its natural condition. Not unless there's a better way??
     
  2. May 24, 2019 #2

    timbucktoo

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    I’ve had a few piston deployed rockets including Sumo and always just left the piston as is. Eventually removed it from Sumo due to lawn dart.
     
  3. May 24, 2019 #3

    aerostadt

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    I have had quite a few pistons and I think I may have sanded every one. I never paint it after sanding it. That increases the diameter and defeats the purpose of sanding.
     
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  4. May 24, 2019 #4

    AfterBurners

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    I just primered which as we know sands easier. I would never paint it
     
  5. May 24, 2019 #5

    heada

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    Depending on the piston material, sealing it well with a paint may be worth while. If the piston is plywood and cardboard, you can help medigate seasonal changes by preventing humidity absorption. If you seal the inside of the body tube as well, you can get a near air-tight seal between them that would require less of an ejection charge.

    Probably not worth the effort but there are edge cases where it might be.
     
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  6. May 27, 2019 #6

    Mike Haberer

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    Regardless of how you finish the piston, use graphite when you prep for launch so make sure it slides well and clean the piston after each launch.
     
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