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Old 07-14-2007, 09:35 PM
CBarber's Avatar
CBarber CBarber is offline
Join Date: Apr 2004
Location: Houston, Texas
Posts: 802
Default Toggle switch protection options

As most of y'all may know, my project is an all electric bird (Velocity SE) with a rotary engine. Since if I loose power things get quite I am using Bob Knuckls' duel alternator/duel battery set up. What I am curious about is the switches in the cabin. Currently I have all the switches up high on the panel a bit right of center towards the co-pilot position. I hope to not have a passanger who would inadvertanlty flip a switch down and off, HOWEVER, you never know what may get tangled or a stray move may flip a switch. If my coil switch or primary injectors get switched off I will start sweating. Also, I don't really mind the switches where they are, but I do have a couple of other places I would like them, but I placed them here as to minimize being bumped.

My question is what other options do I have to either guard against accidental deactivation. I have purchased a couple of aviation locking toggles from ebay, but they are kinda small and may not be up for the task (but at $13.00 for twoI couldn't go too wrong...they may work for my coil switch and primary fuel). The regular priced DPDT (for my contactors and injectors) seem to start at close to $60.00 a piece...a bit much for my police salary if other options will surfice.

I have also considered installing some of the switch guards you see in old nuclear missle bunker movies that they would open to expose the firing buttons for the big ol' missles. I considered installing them upside down (which is really easy) so that they are on when the cover is closed thus making the switch impossible to turn off by mistake. This seems really fool proof, however, the guards, while cheap, are pretty big and do not look all that, well, elligant.

Also, I was watching the Astronaut Farmer last night on PPV and saw the little hard wire loops that where installed next to the switches on each side of the individual switches in his space capsule and this reminded me of the ones NASA used to use....maybe still do. Donno. These seem to be just half circles that make grabbing the switch very deliberate and minimizes potential knocks. Finally, it seems as if I have seen bars held in by springs that lay across a series of switches to keep them in place.

What say ye? Insight? Wisdom? Warnings? Observations? WAG's?


All the best,

Chris Barber

crossed posted on Reflector, FlyRotary, Aeroelectric Connection email list & Canard Zone forum
Chris Barber
Houston, Texas
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Old 07-14-2007, 10:08 PM
John Slade's Avatar
John Slade John Slade is offline
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Join Date: Apr 2004
Location: KWST
Posts: 3,836
Default Re: Toggle switch protection options

I'd leave them the way they are, Chris, and stop worrying. High up on the panel there's little chance that they'll get accidentally hit. Sane passengers don't tend to mess with switches while airborne. In the very unlikely event that someone flips off a set of coils or injectors, or both, the engine will keep running. If they switch off BOTH injector or BOTH coil sets, you have bigger problems than just a stopped engine. Just break their wrists to discourage further difficulties, flip the switches back on, land at the nearest field and hand them over to the men in white coats. You'll be amazed at how fast you can react to such an event. Learn your way around the cockpit in the dark. There could be an occasion when you WANT to quickly disable a set of injectors, and you don't want any wire loops ot toggles in the way.

Astronaut Farmer is a great movie! At the end I promised Char I had no intention of moving on to space rockets....
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Old 07-14-2007, 11:08 PM
David Staten's Avatar
David Staten David Staten is offline
Rotary Powered Velocity
Join Date: Jul 2004
Location: KEFD, Houston Area, Texas
Posts: 441
Default Re: Toggle switch protection options

Originally Posted by John Slade View Post
I'd leave them the way they are, Chris, and stop worrying. High up on the panel there's little chance that they'll get accidentally hit. ....
I think we should just put a pit bull in the back seat, and if someone other than the pilot reaches for the switches, the dog will give behavior modification therapy to the offending party.

Actually, one idea that appeals to me is using a bar-like switch guard, which i think Chris alluded to as being NASA style.

The home depot solution is to use tubular drawer/cabinet handles - the kind that look like 1/4" aluminum polished rod, in a C or U shape that is secured with a screw into threaded ends of the rod. This drawer handle would serve as a bump guard, as well as a place to rest fingers when actually actuating those toggles.

and example: 0401+502158&marketID=401&locStoreNum=8125
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Old 07-15-2007, 03:13 AM
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JonC JonC is offline
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Join Date: Jul 2004
Location: Mountain View, CA
Posts: 997
Default Re: Toggle switch protection options

You can also do the U-bolt between switches. Makes it hard to hit the switch without doing it on purpose and also makes it so that you only hit one switch at a time even in heavy turbulence.
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Old 07-15-2007, 08:08 AM
Waiter's Avatar
Waiter Waiter is offline
Join Date: Dec 2004
Location: Northwestern Ohio
Posts: 1,096
Default Re: Toggle switch protection options


I like these guards because they fit under a standard switch. Part # MS24417. Newark Electronics has them for $6 each. (I just checked, they are on back order). They may offer some protection against inadvertent bumping, i.e. climbin in and out of the plane or passing something back to the rear seat.

I like them because they make finding that critical switch very easy, especially during turbulance. its the one with the guard on it.


I use one of those locking switches for my landing gear, its a three position. The part number is S-7AL-R0. I get them at Digikey for $14.

I think the two position (DPDT) switch is S6AL-RO, and costs about $14 also.


Be carefull how you use the guards that have the spring loaded flip cover. Example: If you wire the switch so that its turned ON when the cover is closed, like your ignition system;

These covers are designed so that when the cover is open, and the switch is OFF, if you hit the cover and it closes, it pushes the switch toggle to the ON position. You could be solving the accidental "Turning off" problem, and replacing it with an accidental "turning on" problem.

Check how the cover behaves, some force the switch to the center position when the cover is closed (use with a three way switch)

Watch e-bay and other autions. sometimes I see things like "Boeing 747 main gear switch panel" that has ten or twenty switches, breakers, and some of these guards and other neat hardware.

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Last edited by Waiter : 07-15-2007 at 08:53 AM.
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