[NRV Rocketry] Questions about outfitting an avionics bay with power-safety flags

Mike Ficco mficco at mindspring.com
Wed Jul 6 19:40:56 CDT 2011

Hello Tweeks,

Personally I've always either used the voltage selector rotary switches you linked to, or used home-brewed screw switches.  I'd not feel terribly comfortable with audio jack switches because they are not designed to carry much current, and because you pretty much need the plug to change the state of the switch.  I've been in the situation where someone had recovered my rocket and I had to describe to them how to power down the electronics over the phone.  That would be difficult with an audio jack setup.

I'm also not a fan of linear "slide" switches because of the ease with which they can be accidentally actuated.  One must be very careful with mounting orientation to minimize the changes for an anomalous high acceleration event such as a cato or sudden change in AOA to actuate the switch.


On Wed, 06 Jul 2011 00:33:14 -0400, Thomas Weeks <tweeksjunk2 at theweeks.org> wrote:

> This is a question for you high power guys who have been shooting H and up
> birds for years.
> Background:
> -------------
> So my first HP rocket is about ready to fly... and I plan on using it to get
> my L1 (H) and L2 (J) certifications. The L1 is no problem. Up, pop, float
> down. But as most of you know.. L2 certification also requires a written test
> (no problem) as well as "Active recovery", or a way of measuring your altitude
> and ejecting multiple chutes at precisely the right times to safely recover my
> rocket.
> Well.. I've now mostly built my avionics bay, or "e-bay" and wired in a GWiz
> LCX flight computer:
> http://www.facebook.com/photo.php?pid=1049573&l=3b9cc7e689&id=1844028171
> http://www.facebook.com/photo.php?pid=1052820&l=fde4de7d63&id=1844028171
> http://www.facebook.com/photo.php?pid=1052821&l=8f9d1e56c2&id=1844028171
> http://www.facebook.com/photo.php?pid=1052825&l=878029acee&id=1844028171
> http://www.facebook.com/photo.php?pid=1052823&l=079bcf0bff&id=1844028171
> http://www.facebook.com/photo.php?pid=1052824&l=d39d643ca4&id=1844028171
> Here are some other pictures of other people's e-bay construction and
> products:
> http://www.vanderbilt.edu/USLI/2011/media.php?gallery=jan_19_2010
> http://www.apogeerockets.com/electronics_bays.asp
> http://www.rocketryplanet.com/content/view/2960/95/#axzz1RIL7aYxk
> My Question:
> -------------
> Anyway.. my question for Bob and other experienced Rocketeers..
> What should I use for my flight computer's power safety switch?
> So you're supposed to have a power arming safety circuit to ensure that your
> ejections charges don't blow before you launch the thing... They usually look
> something like this:
> http://aeroconsystems.com/cart/products/RBF4-47-10.html
> And are hung off something like a 1/8th " audio jack (where the normally
> closed circuit is open when the audio plug is in... and removing it completes
> (or closes) the circuit.. and powers up the computer).  However.. I hear that
> the flight vibration can really make those switch contacts bounce around,
> which can reset the flight computer.. which leads to big expensive crashes. So
> a lot of folks use these high-G rated switches like this:
> http://aeroconsystems.com/cart/products/PCB_Screw_Switch-110-0.html
> or
> http://www.aeroconsystems.com/electronics/switches.htm
> Not nearly as cool/sexy as the "yank it out" audio plug that I want to use. :)
> So what do you other HP folks recommend? Slide switches? Hard wired toggles?
> Audio jack/plugs?
> Tweeks

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