Raven 3: Is this right?

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As to series vs parallel eMatches, I would not use them in series as an open circuit on one would disable the other, thus negating any perceived redundancy.

With parallel, a short on one will disable the other, negating any perceived redundancy. :wink:
 
Duplicate altimeters, duplicate batteries, duplicate switches, duplicate ematches, and duplicate charges... THAT is how you do redundancy. Anything else will have a single point of failure "somewhere".
 
With parallel, a short on one will disable the other, negating any perceived redundancy.
Of course! Thinking about the fact there is a filament involved it is much more rare for a filament to go short circuit (does happen!) and much more likely it acts like a fuse if it has a weak spot. You just need to figure out which way the probability might fall to reduce risk :wink:

Duplicate altimeters, duplicate batteries, duplicate switches, duplicate ematches, and duplicate charges... THAT is how you do redundancy. Anything else will have a single point of failure "somewhere".
Nowadays I use duplicated altimeters, batteries and switches for all the L2/L3 sized rockets. One battery for the electronics, and typically one for each pyro. Sometimes I might fire the last secondary pyro from the altimeter battery as long as the altimeter doesn't need to do any further deployment. That way if the pyro takes out the alt then nothing else is compromised.

The only time I use multiple (parallel) eMatches is when I use an AARD for releasing a chute, since there is only a single charge in the single well.
 
Duplicate altimeters, duplicate batteries, duplicate switches, duplicate ematches, and duplicate charges... THAT is how you do redundancy. Anything else will have a single point of failure "somewhere".

You left out duplicate operators, otherwise you still have a single point of failure.
 
Ummmmm, Adrian. Can you alleviate some fears from us old Stupidheads if our rockets have to sit on the pad for "a long time", say like an hour or more with your
mag switch attached to a Raven 1,2 or 3? How about some comments on cold weather flying for our friends up north with 170mah batts?

Here are 3 options for going getting longer time on the pad:

1. Use a small battery for the pyros and a separate large battery for the altimeter power that's connected just between the +In and Gnd. It can be arbitrarily large in amp-hours, but it should stay at 1 Lipo in series to avoid putting unnecessary thermal stress on the components. People who ask about using 2 separate batteries are usually interested in putting a larger battery on the pyros (which is not recommended, as discussed above) but using a big battery for the non-pyro function actually makes sense if you're concerned about long pad waits.

2. Use a larger capacity battery with external current limiting resistors. This is more for those comfortable with electrical engineering. Measure the current with the added resistors providing the only resistance when the battery is full, and also test with the resistors and an example ematch with the battery near empty. Channels 3 and 4 have more headroom on the acceptable current for this approach.

3. Use a 9V battery, which is typically around 450 mAhrs and has built-in resistance of about 2 Ohms if I recall correctly.

Chute! I have an MD 38mm rocket with your mag switch and Raven 2 un-flown ready to go as soon as the weather breaks. Now I can go to a so-called "private" launch
were I can connect the battery, shut off the electronics with the magnet immediately, go to the pad, set said rocket down (with the weird 3.7v 180mah battery on the pad)
flick the magnet to turn it on and how long will the Raven 1,2 or 3 last before launch to give a nominal flight with a DD rocket ?

At a private launch, and I mean a launch that is advertised on the internet and elsewhere where few people show up and I can get the rocket off within 10 to 15 minutes I wouldn't
care but if at a regional/national launch were the wait could be longer, much longer, please alleviate mine (and maybe others fears) about long wait times,

Flew at a MWP launch a few years ago with another makers product but I had a 2S 1300 Mah lipo on board. I was royally ticked off as it took close to an hour to get the rocket
into the air but I DID NOT fear a failure due to battery exhaustion. "Well, we want'a get's off these L1 certs first!!" I didn't give two sheets to the breeze cause I had
the "POWER". Jes', looked at the EggFinder LCD every now and then and listened to the reassuring "I'm still connected beep." And I was happy and got the rocket back in spite of "no maps". Got good data too within the limitations of the device. Not trying to start a "pissing" war but sincerely seeking legitimate information. Granted, I elected to use a big freaking battery. It was my choice and turned out to be a decent one for the conditions. Best regards, Kurt

A 160 mAhr battery would still work with the "close to an hour" pad time, as long as it starts out fully charged and it's not too cold out.
 
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