mercury switch deployment

[FredA]

I'll admit to using one a long time ago.
On a saucer for testing motors.
The saucer was big enough in diameter that it stopped at burnout.
A mercury SW was a cheap and dirty method to blow the chute as all you need is the mercury switch, a second safety switch and a battery.
I wanted to pull the rip-cord at burn out [which was also apogee] or if the rocket tilted over for whatever reason.
So a mercury switch was a valid solution except for the risk of breakage.

I did install mine in a "crash-proof" metal container....and it's long since been retired.

 

[OverTheTop]

WAs it this video?

I don't think so. This looks to be a more contemporary version than the one I remember. Same concept though, with three switches, IIRC.

 

[tab28682]

I'll admit to using one a long time ago.
On a saucer for testing motors.
The saucer was big enough in diameter that it stopped at burnout.
A mercury SW was a cheap and dirty method to blow the chute as all you need is the mercury switch, a second safety switch and a battery.
I wanted to pull the rip-cord at burn out [which was also apogee] or if the rocket tilted over for whatever reason.
So a mercury switch was a valid solution except for the risk of breakage.

I did install mine in a "crash-proof" metal container....and it's long since been retired.

In that situation and back at that point in time, it would make perfect sense to use a mercury switch in a very high drag rocket.

These days, similar situation, I think I would use RC controlled ejection.