Revision to Tripoli Rule Regarding Wireless Remote Switches

Discussion in 'Rocketry Electronics and Software' started by Steve Shannon, Feb 4, 2020.

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  1. Feb 25, 2020 #901

    warnerr

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    Im glad Tripoli is deliberating longer this time from their meeting with the venders. We can only hope that a better written rule emerges that is less specific on the methods that must be used. Thanks for the hard work to all involved!
     
  2. Feb 25, 2020 #902

    Steve Shannon

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    We met on Saturday for an hour and forty minutes. David Wilkins will be putting together minutes for the attendees. I wouldn’t say we settled much yet, but we had good participation.
     
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  3. Feb 25, 2020 #903

    cerving

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    It was a productive meeting, there were a lot of different things discussed in relation to range safety in general... it wasn't all about "switches". I think some good things will come of this, details should be coming soon.
     
  4. Feb 26, 2020 #904

    GlueckAuf

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    So I read this morning the just-released Tripoli March report, and it confirms that the Eggtimer Wi-Fi switch, Proton, and Quantum are the sole “Tripoli-approved” remote switches (other than the special-use Kate 2.0). Does that mean my Featherweight magnetic switches are banned entirely from use at a Tripoli event if used for energetics-driven deployment? Or is there a special procedure I can follow to still use them? Is their approval pending, or was it denied?

    Good skies,
    GlueckAuf
     
  5. Feb 26, 2020 #905

    Eric

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    The magnetic switch has nothing to do with this recent rule. It is not a Wi-Fi remote switch.

    As previously mentioned several times in the above posts. Tripoli had never approved magnetic switches. They do not provide a physical disconnect of power to the energetics.

    But the are still completely acceptable at any launch. As long as they do not have a battery connected to them until you're out at the pad.
     
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  6. Feb 26, 2020 #906

    GlueckAuf

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    No, the topic of the discussion here and in the Tripoli Report is “Wireless Remote Switches” and “Remote Power”, respectively. Wi-Fi is a subset of Remote Switches, though Wi-Fi switches are the only Approved solution right now.

    There is no clear guidance from Tripoli where that leaves magnetic switches, like the Featherweight example. Banned? Or must a yet-undescribed procedure be followed if magnetic switches are used exclusively and energetics OR battery left disconnected until out at the secondary prep area. With an Unapproved mag switch, this reconnection would have to be done with the rocket on the rail and vertical, as I interpret it, and, for many of us, is pretty much impractical.

    Good skies,
    GlueckAuf
     
    Last edited: Feb 26, 2020
  7. Feb 26, 2020 #907

    Eric

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    Correct, the topic here was wireless remote switches. And a magnetic switch does not fall into that category. Being one inch away from the switch with a magnet is not remote. Magnetic switches do not fall into this ruling in any way.

    Again, as previously stated several times the sole use of a magnetic switch has never been approved to control energetics. Although it hasn't been specifically disapproved either. NFPA 1127 says that energetics must be inhibited. Tripoli BoD has only stated that an electronic disconnect does not meet the inhibit requirement.
     
  8. Feb 26, 2020 #908

    Steve Shannon

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    I specifically answered you above. Nothing about that has changed. You don’t have to go back and reread all 900+ posts, but if you just re-read your own posts as I’ve copied above you’ll see that you’re concerned over nothing and that at least a week ago you felt the question had been answered.

    Eric is correct. We have not banned anything. We have limited when electronics can be powered up.
     
  9. Feb 26, 2020 #909

    GlueckAuf

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    Thank you, Steve. “Not banned” Good.

    Last question from me, and I promise to fade into obscurity.

    Condition: Post-RSO inspection (passed), battery connected to mag switch, mag switch in OPEN state (not illuminated, altimeter not powered nor beeping), and deployment squib(s) carried in hand as is motor igniter. No staging involved. Walked downrange to secondary prep/pads area.

    Question: May I connect the squib(s) with the rocket laying on the secondary prep table and pointed in a safe direction, or must my rocket be on the rail and vertical before I may connect the deployment squib?

    Good skies,
    GlueckAuf
     
    Last edited: Feb 26, 2020
  10. Feb 26, 2020 #910

    Steve Shannon

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    You absolutely can connect the ejection charges (deployment squibs) at the second table if you want, but the igniter shouldn’t go in until on the pad.

    But please do not fade into obscurity!
     
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  11. Feb 26, 2020 #911

    GlueckAuf

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    Vielen Dank, Herr Shannon. :)

    Good skies,
    GlueckAuf
     
  12. Feb 26, 2020 #912

    Steve Shannon

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    Bitte sehr!
     
  13. Feb 26, 2020 #913

    ksaves2

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    It behooves launch organizers to have that "second" table nearby since I've been told I can't take the rocket back to my vehicle to plug in the battery and turn off the mag switch. It t'ain't rocket science to make sure one is careful with the direction the nosecone is pointed when turning "off" a mag switch with charges attached. If the RSO's are going to be sticklers, they'll probably require fliers
    to take their ebays apart to "prove" the battery is disconnected from a mag switch setup. When I previously flew, I'd have everything connected up with the mag switch off. If the switch is off, the rocket isn't going to make a peep and the only way to be certain the battery is "disconnected" is make the flier take the ebay apart. Making sure my electronics functioned as advertised in advance with contained ematches (no BP) served me well and screened out a defective short (which is rare) so the method of pre-prepping, attaching the battery and then shutting off with the mag switch worked fine and is safe. A rule is a rule though.
    This makes it harder to prep and launch the smaller diameter rockets that contain a mag switch alone. Larger rockets have the room for all the switches you want to introduce. Kurt
     
  14. Feb 26, 2020 #914

    mikec

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    In this case, a rule is a spontaneous interpretation of the word "inhibit" that causes the standard use case of Featherweight magnetic switch products to be disallowed. There are workarounds that range from less safe to completely impractical.

    I'm hoping the BOD will reconsider this position but see little reason to be optimistic so far.
     
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  15. Feb 26, 2020 #915

    Steve Shannon

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    Probably the main takeaway (agreed to in principle by all present) from the meeting Saturday with the manufacturers was the need for the flyers to be able to demonstrate that their avionics are completely powered down, both for their own benefit and for the safety of those around them.
    How should that be done?
     
  16. Feb 26, 2020 #916

    Steve Shannon

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    Would you and others work together to do such an analysis?
     
  17. Feb 26, 2020 #917

    mikec

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    What does "completely powered down" mean?

    With a rocket with a Featherweight Power Perch, I know the altimeter is powered down because it's not beeping, the same way that I know it's not powered if I were using a mechanical switch. And I trust, because I've used it a lot and I have confidence in the vendor, that the magnetic switch isn't going to turn on and provide power without definite positive action on my part.
     
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  18. Feb 26, 2020 #918

    wsume99

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    Maybe I'm reading this too literally but what you just stated is very different from what has been previously discussed. Is the standard to demonstrate that avionics are completely powered down or that the energetics are physically isolated from power? It was previosuly stated that avionics could be fully powered as long as there is a physical break between the avionics and the energetics.
     
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  19. Feb 26, 2020 #919

    cerving

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    Regardless of what criteria TRA may ultimately set, you need to prove to the RSO that your rocket is sufficiently "inhibited". Whether it's because your altimeter isn't beeping, or a "remove before flight" pin is inserted, or your remote arming device says that power to the deployments are "off"... well, that's what's up to the BoD.
     
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  20. Feb 26, 2020 #920

    Steve Shannon

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    Not a spontaneous interpretation, but one that has been used by others as well.
    I sought the opinion of the person responsible for the wording in NFPA 1127 and he agreed that when he wrote it he meant “physically disconnected.”

    Here’s how Cal Poly defines an inhibit in their range safety document for Cube Sats:

    • Inhibits
    – Physical devices that interrupt the “power path” needed to turn on a potentially hazardous device
     
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  21. Feb 26, 2020 #921

    mikec

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    IMHO that was an unclear thing to do, because "inhibit" does not mean "physically disconnected" universally. And even if it did, "physically" could mean "in hardware not in software", it doesn't necessarily mean "mechanical not electronic".

    There is plenty of wiggle room in the definitions of "inhibit" (and for that matter, "physically disconnected") for a magnetic switch to satisfy that requirement, if the BOD wanted to do so.

    Every project I have flown at BALLS used Power Perches in a way that is now judged to be unacceptable, and I am struggling to understand the supposed benefit of that decision.
     
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  22. Feb 26, 2020 #922

    Steve Shannon

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    That’s a good point. Even though I mentioned a “takeaway” above, it’s not a rule, but it could lead to one. We have to accommodate disconnecting energetics also.
     
  23. Feb 26, 2020 #923

    Steve Shannon

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    Hopefully these meetings with the manufacturers will help us determine what “inhibit” should mean in this context. I’m open to solid state switches as well as mechanical switches.
     
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  24. Feb 26, 2020 #924

    jderimig

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    IMHO the manufacturers should not define what inhibit should mean, that should come from the writers of the NFPA1127 rule to understand what their intent was.
     
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  25. Feb 26, 2020 #925

    Steve Shannon

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    And their participation is welcome.
     
  26. Feb 26, 2020 #926

    Eric

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    If a connected Wi-Fi switch or magnetic switch doesn't inhibit as per the writer of NFPA 1127. Then the Tripoli BoD has given us approval to disregard NFPA 1127.

    NFPA 1127 says energetics must be inhibited until the rocket is vertical. I could not find anywhere in the writings that it says you're allowed to make up your own safety area and disregard NFPA requirements.

    So from your secondary assembly table until the rocket was vertical you would have uninhibited energetics.
     
  27. Feb 26, 2020 #927

    Charles_McG

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    NFPA 1127 says ‘inhibited’, not disconnected. It could have, but it doesn’t. A dictionary definition of ‘inhibit’ is to ‘hinder, restrain, or prevent a process or action’. There are many ways to accomplish that - with varying degrees of convenience and reliability.

    While ‘inhibit’ may have technical definitions in other industries, NFPA 1127 specifically addresses high power [model] rocketry. In the absence of a more specific definition, I think the TRA (and NAR) are relevant bodies to aid interpretation. Whether they wish to establish more than one level of ‘sufficiently inhibited for the different situations’ is completely within their purview. They are arranging the insurance and explaining things to underwriters. Even if it goes beyond NPFA 1127.

    If a large number of fliers feel the TRA is too restrictive and doesn’t serve the aspects of the hobby that they wish to explore and advance, they can either elect a new board that agrees, or create a new organization and explain to an insurance company why their more general interpretation of NPFA 1127 is insurable.

    It’s not like it hasn’t happened before.
     
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  28. Feb 26, 2020 #928

    Kelly

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    This seems excessive. There needs to be a certain level of trust between the RSO and the flyer. I don't need to demonstrate where the CP is, I don't need to demonstrate what engine is in it or whether it has sufficient thrust, I don't need to demonstrate that it will stay within the waiver, etc. Generally I expect the RSO to ask me some questions about these things, and then take my word for it if I have reasonable answers regarding sims, etc.

    Not sure how you could demonstrate this, anyway - suppose I mechanically disconnect between the electronics and the charge. I can show the untwisted wires, or the 'remove before flight' pin, but demonstrating that these actually do what I say they do requires opening up the rocket. Or if I have (say) a beeping device which controls no energetics, and another device (inhibited) which is silent because it us unpowered. The RSO is going to have to take my word for it that the beeping device isn't connected to energetics.

    It seems like we're making a baseline assumption that flyers are going to lie to RSOs. Is this really the hobby we're in?
     
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  29. Feb 26, 2020 #929

    wsume99

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    To me there is a big difference between ignorance/negligence and deception. I hope the intent of the rule change (which I believe is the case) is to prevent the former and not the latter. I think it's reasonable to expect that a RSO would be able to differentiate between the two with some simple questions.
     
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  30. Feb 26, 2020 #930

    Steve Shannon

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    Exactly.
     

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