3 switchs???

[jraice]

I am thinking about using three switchs on my next project. They are sold by areocon, they are called throughmount slotted switchs. They have a small slot and you use a screwdriver to turn them. I want one to turn the elelctronics on and the other 2 are for shunting the e-matchs. Is it safe to use 3 switchs?

 

[wickball]

I am also using 3 switches (from Missleworks) for my Magnum dual deployment and am not aware of any issues here. I do have a question though. I am planning on wiring 2 of the switches in series with the 2 charges to open their circuits until launch while you are going to shunt yours. Is one way better than the other?

wick

 

[KarlD]

Shunting the leads of the E-match is better that having an open circuit. The possibility exists of the open circuit to the E-matches acting like an antenna. A strong enough stray RF Signal or a static discharge may ignite them. It chance is remote…but it still exists.

 

[rstaff3]

It is also possible to for switches to fail due to the Gs and vibrations during boost and many people recommend not to use a switch to power the electronics. Failure modes would include the altimeter powering up during flight and thinking it is at ground level and/or getting confused about apogee. I have heard that some may fire the charges at power up, but don't know what if any models are still subject to this is problem.

How big a problem is this? I don't know. It would be worse for a mach transition. Still, my electonics will run all day and I choose to just deal with the charge circuits. I still maintain that electonics problems are more likely than static dischrges, especially once installed. Shunts would help here too. Nevertheless, so far all my rockets have just broken the path to the igniters.

 

[KarlD]

What would induce more G-Force on the switch? Boost or ejection charge?

I am building my first Dual-deploy system, and it is still possible to change the direction of the switch throw. I assumed that boost would have more G-force so I currently have the switch setup to pull down on power up. It should not have any problems during boost, but during ejection charge?

Guess I could always tape it for an extra safety margin…

 

[jraice]

The switchs I plan on using are not sliding switchs, they cant slide into the other position. How could they fail???

 

[rstaff3]

Karl, I really don't know. The issues I discussed would be internal to the switch and involving the contacts.

 

[jraice]

How can a switch fail? as long as the force wont make the switch go in the other position what could go wrong

 

[KarlD]

I am using the stock switch shipped with the Transonic P6k. The switch needs a modest bit of effort to switch contact sets. It is mounted vertically to save space, so I guess next time I will use a rotation switch or mount it horizontally.

Of course, severe vibration would effect the switch whatever switch style or mounting orientation that is employed.

LOL!!

Practice makes perfect!!

 

[rstaff3]

I know this is theoretically possible - I know all about switch bounce - but how likely it is I don't know.

 

[jraice]

I just don't understand how the vibration can make the switch do that? It would only be during the high thrust part of the flight, right, not during the coasting. My electronics can be unpowered for two seconds. Would this bounce last for any time even close to that or would it just a quick jolt?

 

[rstaff3]

The basic thought is that the contacts have mass and hence are are affected by the forces exerted on them. A sudden 'stop' and their momentum might move them slightly. All it would take is a momentary chatter/loss. I think Bob Krech has worked on space hardware and might shed more light on how likely this is in a rocket environment.