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 15, 2020 #811

    Speaknoevil

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    Yes closed, but it actually depends on where on the threads your "whack" is located on what it prevents in, out, or both. :D
     
  2. Feb 15, 2020 #812

    NikeMikey

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    Put it in the rules! Now that it has been pointed out to TRA that screw switches can fail closed we must ban them or be liable for any accidents. "The sky is falling!" :haironfire:

    Can we please just take a step back; rescind this ill-conceived and poorly implemented, knee-jerk rule; quiz the manufacturers and knowledgeable members; collect some data; and make a reasoned, rational decision on what, if anything, needs to be done?

    NikeMikey
     
  3. Feb 15, 2020 #813

    g.pitts

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    Next time you fly somewhere, be sure and ask the flight crew if they got their training from YouTube. [emoji23]
     
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  4. Feb 15, 2020 #814

    Speaknoevil

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    Ah, now I get the logic. You sly fox!!!
     
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  5. Feb 15, 2020 #815

    ksaves2

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    Sooooooo, I guess it’s perfectly fine to take my mag switch/wireless rocket without the battery connected to the RSO table for inspection. Take it back to my prep area. Prep it to fly in the way I see fit. Button up the rocket with the mag switch off or the wireless inactivated and then go to the pads to fly? Is that OK? I’m not talking about staging electronics here. Kurt
     
  6. Feb 15, 2020 #816

    davdue

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    With a magnetic switch in a rocket that requires a ladder you could tape it to a stick or something. Now I don’t know how you would hear the altimeter beeping the continuity to know it’s armed and ready. But at least when you go on the ladder you wouldn’t be arming it, assuming you got it armed with the stick.
     
  7. Feb 15, 2020 #817

    Voyager1

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    That works well on my screw switches with the covers installed. I doubt whether the vibration and Gs experienced between the prep table to the RSO, and then on to the pad, would move those screws! There will generally be a simple solution to most of these issues.
     
  8. Feb 15, 2020 #818

    NikeMikey

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    Problem is -- nobody really knows what is OK!
     
  9. Feb 15, 2020 #819

    NikeMikey

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    Just out of curiosity -- does anyone know of an RSO/Safety check-in person ever refusing to OK a rocket that was presented for flight with just a mag switch or WiFi switch or WiFi-activated altimeter with charges, I mean energetics installed?
    NikeMikey
     
  10. Feb 15, 2020 #820

    Pariah Zero

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    May I mention an electronic failure mode which has no solution? One which has nothing to do with switches, transistor failure modes, or pretty much anything mentioned thus far?

    The way electronics are built is yet another problem: solder. Solder can be brittle — even more than in the past thanks to the forced migration away from leaded solder. (The metallurgy of solder is insanely complex, and there are a lot of unanswered questions).

    One solder problem is particularly relevant for rockets is brittleness. A famous example is the iPhone 6+ “touch disease”, which was caused by brittle solder joints cracking and breaking due to flexing of the phone while in a pocket. I had four (!) devices succumb to it. The phone would work fine much of the time, but a bit of a bump, and the screen wouldn’t work anymore. Some creative bending would temporarily restore functionality.

    Either way, the point is: even very experienced professional fabrication with state-of-the-art equipment can result in brittle solder that fails under moderate mechanical stress. It happens with space launches frequently

    Even a perfect flight can crack solder. More importantly, the failure won’t be obvious. Such a crack at a MOSFET gate leaves the gate floating. Even proper use of pull down resistors can’t defeat cracked solder. At that point, whether the transistor is “on” or “off” up to ambient static electricity, and a pinch of quantum fate. The transistor still ”works” in that the gate voltage determines current flow... but the circuit is very broke.

    “Never leave the gate floating” is the lesson from my electrical engineering professors. Now you know why.

    My point is there are a lot of things that can cause electronics to fail, regardless of how reliable a transistor or switch is (or isn’t) in isolation.

    A rough landing can render electronics broken when bumped, but works fine on the bench.

    Draw whatever conclusion you wish, but my own education and professional experience in electrical engineering lead me to agree with Tripoli.
     
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  11. Feb 15, 2020 #821

    rharshberger

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    IMO, no, sorry, once I as RSO have put my "stamp of approval" aka initials on your flight card its next stop is to the flight line, if it returns to the pits and is opened up for any reason it has to be re-rso'd, thats only my opinion but my reputation is on the line as well.
     
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  12. Feb 15, 2020 #822

    Voyager1

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    Totally agree!

    With regard to the build quality and soldering skills of flyers assembling their own electronics, considering the number of people on this forum who are a little challenged in this area (and they frequently admit to it!) is sufficient evidence to suggest that not all electronics systems can be declared fault-proof, and that's before we add any mechanical switches. After 40 odd years in electronics I have seen all sorts of system failures - more often than not they have been electronic (or firmware), not mechanical. However, they can all fail under the right circumstances.
     
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  13. Feb 15, 2020 #823

    DaveW6DPS

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    This is a new requirement, so probably not.

    I can tell you that at our only launch since the rule was implemented I was the RSO who inspected Chris Erving's rocket. He had added an additional circuit opening device to comply.
     
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  14. Feb 15, 2020 #824

    DaveW6DPS

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    Dupe...
     
  15. Feb 15, 2020 #825

    Pariah Zero

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    I understand your point, that vibrating screws almost always move in or out under vibration.

    But... it’s also a well known, predictable, solved problem. Heck, even the instructions for LOC kits tell you to epoxy eyebolts to the airframe so they don’t back out.

    Here are three solutions less permanent than using epoxy on the threads:

    • Lock nuts
    • Removable thread lock — they don’t affect the electrical connection. I pull several amps through nuts & bolts secured with blue loctite all the time, and the screw doesn’t move. (I fly Nitro R/C Helicopters — otherwise known as “thousands of parts trying desperately to get away from each other.”)
    • Clean the screw head with a good solvent, and tape the partially threaded screw head in place.
    • Remove the screw entirely. Clearly it means there’s a chance of losing the screw, but I just don’t see much hardship in carrying a few. (Yes, Parkinson’s and arthritis are a thing- but ‘more screws’ isn’t the only option.)
     
  16. Feb 15, 2020 #826

    roytyson

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    I have never installed a manual switch on 15 high power rockets. I will often get asked where my switch is and I will just show them the Eggtimer screen, and they all have said "OK". No issues ever.
     
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  17. Feb 15, 2020 #827

    Steve Shannon

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    Sorry, Kurt, I was eating a New York strip with my family for Valentine’s Day.
    Once you’ve cleared the RSO you head out to the range. There could be a table ahead of the flight line or off to the side but away from the spectators where you stop and reconnect your battery. Then you continue out to the pads.
     
  18. Feb 15, 2020 #828

    lspikol

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    Exactly...I used the table to load the powder...my electronics were connected and my ematches were connected,but no powder was in the rocket..the worst that could happen at my car or at thr rso table is the ematch could light.Is there a problem with this work process...enlighten me.
     
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  19. Feb 15, 2020 #829

    cerving

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    Good points. We use 1/16" boards instead of the commonly-used 1/32" to reduce flexing, and we ship leaded solder (which is still allowed as a RoHS exemption for hand-soldering). The FET's and BJT's are all through-hole parts... the solder inside the vias isn't going to be affected by any board flexing. That largely mitigates those issues.
     
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  20. Feb 15, 2020 #830

    cerving

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    I think that would work under the rules too, because it's technically not an "energetic" until you add the powder. You're still going to be doing a bit of work at the table out on the range, but you don't have to add another switch and you don't have to open up your AV bay... just put everything together and add the screws and/or shear pins.
     
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  21. Feb 15, 2020 #831

    Steve Shannon

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    Absolutely!
     
  22. Feb 15, 2020 #832

    Pariah Zero

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    Yee haw! Leaded solder solves so many problems...
     
  23. Feb 16, 2020 #833

    Maxter

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    This has gotten so complicated , maybe I'll just quit rocketry.....Or use twist and tape that powers my switch that controls my switch.
     
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  24. Feb 16, 2020 #834

    Adrian A

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    If "no power" means "no power past an independent power switch", then people can continue to use Featherweight products (24mm av-bay, 29mm av-bay, 38mm av-bay, Power Perch) as they were designed, and as they have been safely doing for over a decade.

    But if it means the battery has to have an air gap at the RSO table, then we have a problem that impacts a whole lot of Featherweight av-bay and Power Perch customers. Particularly for the 24mm, 29mmm, and 38mm av-bay products, this would mean assembling the av-bay from scratch at the pads. They are intentionally designed so that the battery is connected first to the magnetically-activated arming switch before almost anything else happens. This way there is no ambiguity about what the power state of the switch is before charges are connected.

    The assembly and safe use of a Featherweight 24mm, 29mm or 38mm av-bay goes as follows:
    1. Connect a Raven altimeter's screw terminals to the header pins on the active bulkhead.
    2. Plug the battery into the active bulkhead. If you had the switch on when you last disconnected the battery, the Raven will be beeping and blinking and now is a good time to turn it off. If the altimeter doesn't come on when you install the battery, use a magnet to turn it on to make sure everything is working and then turn it off.
    3. Install the threaded rods onto one bulkhead using 6 or 8 nuts depending on av-bay model
    4. Install charges on the bulkhead with the rods and install it on the rocket. For my rockets, this means sending it down the main chute tube with the piston and chute behind it.
    5. Install the other bulkhead on the other end of the coupler, using 3 or 4 more nuts on the threaded rods to clamp the coupler between the two bulkheads
    6. Install the charges on the 2nd bulkhead. It's now ready to take to the RSO table and the pads.
    Note that after step 2, the switch is in a known, confirmed, safe state, with no power applied to the altimeter. At that point the system is at least as safe as one with a disconnected mechanical switch. This would not be true if the battery were connected separately later. And because the system is designed so that the Raven and the battery are connected directly to the active bulkhead with no wires, it's not possible to put a mechanical interrupt between the battery and the rest of the circuity without either cutting traces and soldering jumpers, or adding an extension cord to the battery that there is no room for.

    If this rule is interpreted as has been recently stated, then 4 products that have been used safely for years would be prohibited without cause for anyone who doesn't want to do pretty much all of their prep work at the pad.
     
    Last edited: Feb 16, 2020
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  25. Feb 16, 2020 #835

    Ez2cDave

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    Bureaucracy, eventually, destroys everything . . .

    Dave F.
     
  26. Feb 16, 2020 #836

    warnerr

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    Used as you have stated, Adrian your product works in a safe manner. There is no easy workaround in my minimum diameter rockets using the power-perch that is what i consider safe under the new PHYSICAL DISCONNECT ONLY rule.
     
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  27. Feb 16, 2020 #837

    Cnorm

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    Interesting how a group of relatively intelligent makers who have used various mechanical switches for years suddenly become paralized by a rule that requires addition of a mechanical switch.

    Interesting the mechanical switches that have been used for years are suddenly unsafe and will kill everyone within a 5 mile radius if they're added to a circuit.

    I don't agree with the new rule or how it was announced but good lord. It's a hobby. It's supposed to be fun. Most rocketeers are perfectly capable of adding a switch. Most rockets can accept one, maybe some need a little ingenuity.

    If some people can't figure out how to make it happen maybe they should consider another hobby. I hear stamp collecting is rewarding and you don't have to figure out any switches.
     
  28. Feb 16, 2020 #838

    NikeMikey

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    Well the same could be said for mag switches! They've been used for years with no problems, but now they are unsafe.

    NikeMikey
     
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  29. Feb 16, 2020 #839

    NikeMikey

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    Sooo. For all these years, apparently not a single RSO has EVER had a problem okaying a mag switch for flight. If these mag switches are unsafe, there must have been dozens (perhaps hundreds?) of accidental firings of ejection charges. Where are all the reports of these near-death experiences? Does the TRA board think all of our RSOs are incompetent? They (RSOs) are supposed to be the last word on what is safe and what is allowed to fly. This recent action of the TRA board, in superseding the prior decisions and, indeed the very role of the RSO, calls into question the validity of our (up until now) practice of launch safety management.

    NikeMikey
     
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  30. Feb 16, 2020 #840

    rharshberger

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    TBH most accidental discharges of deployment charges have happened on the rail or in the pits during assembly THAT I HAVE SEEN.
     
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