Will ejection charge corrode electronics?

Discussion in 'Low Power Rocketry (LPR)' started by Nacho, Nov 9, 2019.

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  1. Nov 9, 2019 #1

    Nacho

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    Hi all,
    I was wondering, how bad is it to expose electronics to the fumes of the ejection charge (this would be for a C motor).
    Thanks! :)
     
  2. Nov 9, 2019 #2

    shonc182

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    I'm not sure if there's a difference between the fumes and cloud of bits thrown away from the explosion, scientifically speaking....

    But the electronics should be completely sealed from any detonation.

    I ruined an altimeter by not sealing the small gap between wires and the small hole they passed through. I believe it's the barometric sensors that are particularly vulnerable.
     
  3. Nov 9, 2019 #3

    seth_cooper

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    The residue left after black powder burns is corrosive

    Corrosion is bad for electronics
     
  4. Nov 9, 2019 #4

    timbucktoo

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    BP residue is corrosive and will harm any electronics. Not immediately but it will over time. If they are exposed, need to wipe them down with alcohol or other solvent that won't harm electronics.
     
  5. Nov 9, 2019 #5

    Nacho

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    Right gotya. Thanks for the replies.
     
  6. Nov 9, 2019 #6

    prfesser

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    Please...don't use the terms "explosion" and "detonation" when describing the ejection charge. Two reasons: (A) they give the wrong impression to the reader, and (B) both are incorrect.

    An ejection charge burns quite rapidly, but it does not explode (unless you're using the BATFE definition of 'explosion', which includes striking a match.) And *nothing* in model or high-power rocketry 'detonates'.

    An internet friend who worked in some sort of professional rocketry job, described the difference between overpressurization and detonation. Essentially, in an overpressurization, the test stand is left in pieces. In a detonation, there are no pieces to be found. :oops:
     
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  7. Nov 9, 2019 #7

    John Taylor

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    JLCU's are exposed by designe.
    Other than a piston rocket like PML's what to do if anything? Perhaps for some reason it is not required. Thanks.
    Anybody?
     
  8. Nov 10, 2019 #8

    dhbarr

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    My JLCRs are in pouches from Dinochutes.
     
  9. Nov 10, 2019 #9

    dpower

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    I always use a nomex chute protector when using a JLCU. Both the chute and JLCU are then protected. A decent amount of Estes/Quest wadding should also be sufficient.
     
  10. Nov 10, 2019 #10

    Nacho

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    What is a JLCU?
     
  11. Nov 10, 2019 #11

    John Taylor

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    Jolly Logic Chute Release
     
  12. Nov 11, 2019 #12

    solid_fuel

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    The U, I believe, was a typo. And then repeated. The common abbreviation is JLCR.
     
  13. Nov 11, 2019 #13

    Kelly

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    Isn't a JLCR fully encapsulated? That is, the electronics are all fully enclosed in a case, and possibly potted in epoxy? I'm guessing there isn't any electronics exposure, even if not using the chute protector.
     
  14. Nov 11, 2019 #14

    solid_fuel

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    The case on a JLCR is around all of the circuits. But there are definitely external buttons and I don’t know if the components are potted. I don’t think they are. The directions, I believe, say to avoid direct exposure to ejection gasses.
     
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  15. Nov 11, 2019 #15

    John Taylor

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    I would expect there to be an opening for the barometric pressure sensor, right???
     
  16. Nov 11, 2019 #16

    Brian H.

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    There would have to be an opening for the barometric sensor, otherwise, the altitude readings would not be accurate. I may be wrong, but I believe the JLCR relies on the wadding to protect it from direct contact with the ejection gasses.
     

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