[NRVR-Members] Rocket PSA: Problems with 110/220 Rotary Switches & LiPo Probs with "Protection PCBs"

Tue Mar 14 13:30:58 CDT 2017

I bought a couple from Ken last time he was here. I picked up a few more last night so I will have three for my flight (one for each altimeter (one GWiz and one PerfectFlight) and one for pyro power).

Thanks though. :)

Tweeks

On Tuesday, March 14, 2017 5:58am, "Jordan Truesdell" <jordan at truesdell.org> said:

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> http://server2.nrvr.org/mailman/listinfo/nrvr-membershttp://www.featherweightaltimeters.com/site/mobile?url=http%3A%2F%2Fwww.featherweightaltimeters.com%2FAv-Bay_Components.php#2705
> 
> Scroll down to screw switches. I've got one if you want to see one in
> person.
> 
> Jordan
> 
> On Mar 13, 2017 9:58 PM, "Thomas Tweeks Weeks" <tweeks-junk2 at theweeks.org>
> wrote:
> 
>> On Monday, March 13, 2017 8:45pm, "Bob Schoner" <bob.schoner at gmail.com>
>> said:
>> > Wow hadn't heard either of
>> > those before. Thanks for passing that on. I know
>> > it isn't elegant but I still am a fan of the simple "twist and tuck"
>> > method. I prefer to leave the wires sticking out and tape them to the
>> > outside of the body tube.
>>
>> Twist and tuck altimeter arming sounds about is simple as it gets Bob (and
>> sounding more and more appealing ;). I'll have to keep that in mind as I
>> finalize my avionics bay. :) Although for this L3, I would have three
>> things to twist and tuck (two altimeters and one dedicated pyro supply)..
>> it would be a shame if it turned in to twist, tuck and touch. <zzzzzap!>  ;)
>>
>>
>> > I guess unless you buy some military or aerospace grade of switches there
>> > is probably a chance of failure.
>>
>> Might be able to ping Dr. Shinpaugh (or other friends I have in the
>> cubesat industry) on sourcing some high-G switches.
>>
>>
>> > I have several rockets with those
>> > switches. I would suspect they are more like Kelly to fail after a hard
>> > landing or some other traumatic event. Not really sure if I will replace
>> > them or take my chances
>>
>> Well.. the root cause of those switch failures hasn't been stated AFAIK.
>> It could be user error (inexperienced folks not rotating them far enough),
>> or some cheap Chinese source that's recently released inferior switches
>> that fail in high G scenarios. Who knows. Like the 9V battery failure
>> experiment I've told you I want to try,  this could represent another cool
>> arduino data gathering experiment for capturing switch contact data
>> watching for high-G contact bounces or faults. Now that I have a bay that's
>> big enough to carry such payloads.. I can finally start getting some useful
>> data out of some of my flights. :)
>>
>> (which is part of why I got into arduinos in the first place)
>>
>> Tweeks
>>
>> >
>> > Thanks
>> >
>> > Bob
>> > On Mon, Mar 13, 2017 at 7:43 PM Thomas Tweeks Weeks <tom at theweeks.org>
>> > wrote:
>> >
>> >> Hey all.. esp you L3 guys.
>> >>
>> >> So I'm designing my ebay for my L3, and I just got the brand new
>> >> PerfectFlight StrataLoggerCF in the mail (the new one with the
>> speaker/LED
>> >> connector).. and there's a little warning handout about common critical
>> >> failure modes they're seeing back from their customers.
>> >>
>> >> Failing 110/220 Power Switches:
>> >> There is new StrataLoggerCF power check feature & very surprising
>> warning
>> >> about using 110/220 AC style switches of this type:
>> >>
>> >> https://www.apogeerockets.com/Electronics-Payloads/
>> Electronics-Accessories/Electronics-Rotary-Switch
>> >>
>> >> I know these are very popular arming switch styles and have been for at
>> >> least a 15-20 years or so (I have a couple in my own parts bin), but
>> check
>> >> out what this leaflet from Perfect Flight is saying about them now:
>> >>
>> >> "We have had numerous reports of failures of the 110/220 rotary switch
>> >> that is sometimes used [...] in rocketry applications. The failures
>> >> typically in one of two ways, either as:
>> >> *  a switch that turns off when tapped or wiggled, or
>> >> * a switch that exhibits a high resistance (several hundred ohms) when
>> >> turned on
>> >>
>> >> [Our new WiringCheck] feature [... which performs a pre-flight
>> >> load/no-load comparative battery test] is intended to reveal the latter
>> >> type of problem, but we still do not recommend the use of this type of
>> >> switch in rocketry applications. [...]"
>> >>
>> >> So in short.. I don't know if this is a NEW issue (e.g. from cheap
>> Chinese
>> >> supply of rotary switches), or an old time gremlin that is just now
>> being
>> >> revealed. Either way, since this info was nowhere on the PerfectFlight
>> >> website or on line documentation (it was thrown in as a warning card in
>> my
>> >> latest purchase), I hope after this is archived in our mail list that it
>> >> will serve as a warning to others. (someone might want to re-post it to
>> >> RocketryForum.com, et al).
>> >>
>> >> Warning About Some LiPos:
>> >> This little info card is useful, and also contains a warning about using
>> >> LiPo cells with over-current protection circuitry shink-wrapped into
>> them,
>> >> as the short condition of some ematches will shut down such batteries..
>> >> causing another type of critical power failure to a critical recovery
>> >> component of your rockets.
>> >>
>> >> Just wanted to share.
>> >>
>> >> Tweeks
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> _______________________________________________
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>> >
>>
>>
>>
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> 