Interesting discussion, I was thinking of using these for my L3 project,
partially bc mounting them is so easy (1/2" hole and done, a 5/8"
counterbore if you're fancy) and the fact that they're basically DPST, so
you only need 3 rather than 6 for L3. I used one in my L2 rocket with no
problems....but if they're having these kind of problems, I may have to
rethink things....And Kurt, in theory 300 cycles sounds like a lot when
you're only launching a handful of times per year, but then there's those
of us that fiddle and fidget with our parts before/while we install them,
so who knows how many cycles are actually on my L2 rocket's switch. :-P
On the featherweight mag switches, I used one in a 38 mm MD that had its
first launch last month, my only complaint about them is that since they
need to have a connection to the battery in order to work, they don't play
nicely with battery charging setups that use your actual avionics board to
charge (Telemetrum, in my case)....I had a battery failure that postponed
the launch of that rocket by a month, and I'm pretty sure it was caused by
trying to charge through the featherweight switch, so I had to add a pair
of connectors so I could bypass the switch for charging. I also slightly
suspected that the battery current rating was a little low, so I also added
another cell in parallel for good measure.
On Thu, Jan 12, 2017 at 9:34 AM, Gregory Lyzenga <lyzenga@xxxxxxxxx> wrote:
Like Kurt, I’ve used the switches for many years without an in-flight
failure, including my L3. But… a couple of things started to make me wary
of them, and I have migrated away from using them in any future projects.
I started to hear the same reports of failures and limited life cycles,
which made me uneasy. And then, although I never had one fail in flight, I
had one in a ground test that didn’t close until I cycled it a few times.
I chalked it up to dust in the contacts, but ever since then have looked at
them with less trust than I used to. So my attitude now is that I got
lucky and did not have my number come up with a fatal failure, but I won’t
press my luck with them any more. (On my latest projects, I’m thinking of
using the Featherweight magnetic switch which is pricey but seems pretty
slick with no moving parts or holes in the airframe.)
- Greg
On Jan 12, 2017, at 9:12 AM, Kurt Gugisberg <kurtgug@xxxxxxxxx> wrote:
I have used those rotary switches for years. I haven't had one split
apart on me and I'm not sure if I have had any failures either, although I
had one in the ill fated Nibbles flight last year with it's total
electronic failure. So it could have failed. I also use screw switches
alot, the Featherweight switch as well as the Aerocon screw switch. They
are, more or less, foolproof.
Also, three hundred operating cycles would be a lot in rocketry.
Kurt
On Thu, Jan 12, 2017 at 8:13 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
Hum, that doesn’t sound good. I’ll have to take a look at what Mike has
designed. It would be nice if a retrofit would fit inside the existing
hole used for the 110/220 switch. Or, perhaps remove the guts from the
110/220 and replace it with something more durable/reliable.
*From: *James Dougherty <jafrado@xxxxxxxxx>
*Sent: *Thursday, January 12, 2017 8:09 AM
*To: *roc-chat@xxxxxxxxxxxxx
*Cc: *Mike Kramer <kramer@xxxxxxxxxxxx>
*Subject: *[roc-chat] Re: Switch Warning with StratoLogger CF
They split in half!!
Ive also seen people turn them and they split in half.
Its designed for a wall socket!
Yes, do what Mike said - great plan; Never seen that fail ...
Sent from my iPhone
On Jan 12, 2017, at 7:22 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
Yes, I would like to try this out Mike, please send the file. I’ll look
into the materials available for the printer. I think I only have PLA at
the moment. How about ABS?
*From: *Mike Kramer <kramer@xxxxxxxxxxxx>
*Sent: *Thursday, January 12, 2017 7:09 AM
*To: *ROC Chat <roc-chat@xxxxxxxxxxxxx>
*Cc: *ROC Chat <roc-chat@xxxxxxxxxxxxx>; James Dougherty
<jafrado@xxxxxxxxx>
*Subject: *[roc-chat] Re: Switch Warning with StratoLogger CF
richard,
I use micro switches with a screw to arm them. Uses a small hole in the
side of the rocket and makes it highly unlikely that the electronics can be
in advertently armed.
Easy to 3d print the mount for it. I will send you a file tonight.
Side note, don't use PLA ( unless it is the pro spec kind) for parts, it
can't survive the temperatures on the lake bed. I'm using PETG or Nylon.
Mike K
On Jan 12, 2017, at 6:47 AM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
I just purchased a PerfectFlite StratoLoggerCF altimeter and the
documentation came with a *Switch Warning* about failures of the
110/220 rotary switch that some people have been using for powering
electronics. High resistance and intermittent connection are noted in the
document.
The document says “numerous reports” of failures, but I’m curious if
this is a problem with a group/lot of these switches or a pervasive problem
to this particular switch or rotary-type switches in general when used for
rocketry. I’ve used these switches in the past and tested the 4 I’m
currently using on two projects. I’m not detecting any problems with these
switches.
Please keep in mind that there are several variations for this make of
switches. Here’s some info on what I have:
Schurter, Voltage Selector Switch, 2 Stages, Series-Parallel, SWA1 or
SWA2
Also, it’s interesting that the spec sheet says that the lifetime is 300
operating cycles (without load).
*So, does anyone have a personal experience that was bad with these
switches?*
Also, I think many people would be interested in recommendations on
arming switches both commercial and custom.
Thank you,
Richard Dierking
----------------------------------------------------------
Gregory A. Lyzenga <lyzenga@xxxxxxx>
Dept. of Physics, Harvey Mudd College (909) 621-8378
Claremont, CA 91711-5990 mobile (626) 808-5314
