Ejection Charge Setup

[Lowpuller]

Please share the order and steps you use setting up ejection charges. Please also share the safety equipment you use. I'm afraid I've been naive but lucky in dealing with my charges..

At the field, assuming 1-2 gram charges, what safety gear do you use for the following?

When do you connect the battery, assume the deployment charges are independently?

When do you connect the ematch?

When do you load the BP?

If things go wrong at the pad, what sequence do you follow to disassemble? Including safety gear.

 

[Exactimator]

For safety I do a couple things. I pour the BP from the 1 lb can into a film cannister and then work with that. Probably not necessary, but if something went really wrong I'd rather have a few ounces go off in my hand than a pound. When I remember, I wear safety glasses.

As for order:
1. Install e-matches (connect to terminal strips).
2. Turn on altimeter and listen for continuity beeps.
3. Turn off altimeter.
4. Install e-match in charge well.
5. Add BP.
6. Stuff in dog barf.
7. Tape over well with masking tape.
8. Repeat 4-7 with the charge on the other end.

I do all this in the controlled environment of my garage where I can focus, there's no wind, and no burning APCP nearby. The altimeter isn't turned on again until the rocket is on the pad.


Not sure what you mean by things going wrong on the pad, but if I needed to pull the rocket back off, I'd power down the altimeters, pull the rocket. Then I'd fix whatever the issue was and reassemble again. Unless something was really wrong I'd leave the charges prepped for the next launch.

 

[Bat-mite]

Pretty much the same here. I always prep at home and carry ready-to-fly rockets to the site.

Oh, let me add that I do a continuity check on my e-matches before I install them in the terminal block. Every once in awhile I get a bad one.

 

[blackbrandt]

Tacking on what Mr John said, I do a continuity check at EVERY point on the entire altimeter hookup. Every wire, every connection, everything. It all gets a continuity check. It takes an extra 5 minutes and can save a LOT of grief. Occasionally, you might nick or damage an ematch while inserting it. The continuity check helps you catch that.

 

[Exactimator]

Tacking on what Mr John said, I do a continuity check at EVERY point on the entire altimeter hookup. Every wire, every connection, everything. It all gets a continuity check. It takes an extra 5 minutes and can save a LOT of grief. Occasionally, you might nick or damage an ematch while inserting it. The continuity check helps you catch that.

Matt, when you're checking everything for continuity are you turning the altimeter on again and listening for the beeps? Or just checking with a meter?

When I'm wiring up an av bay, securing the wires into the terminal strips for the batt, switches, wires between the alt and terminal strips on the av bay bulkplate, I do two things.

First, I pull test the wire. More than a couple times it's come right back out, meaning I somehow missed the wire with the terminal screw.

Once they're all secure, I look at each connection with a loup I got from Fry's. Just a small one with an LED light on it. I make sure everything looks right and there's not a stray strand touching its wire neighbor. I caught that once.

Once I've done that, I'm confident everything is correct and secure from the altimeter to the bulkplate terminals. When prepping charges, I just focus on the e-matches. I did forget to list that on my rockets without redundancy (and for my L3) I'll check the resistance of the e-match with a meter.

Otherwise, I figure if I'm getting continuity beeps in my step 2 above and again at the pad, I'm good. Although double-checking everything certainly wouldn't hurt.

 

[Bat-mite]

Matt, when you're checking everything for continuity are you turning the altimeter on again and listening for the beeps? Or just checking with a meter?

When I'm wiring up an av bay, securing the wires into the terminal strips for the batt, switches, wires between the alt and terminal strips on the av bay bulkplate, I do two things.

First, I pull test the wire. More than a couple times it's come right back out, meaning I somehow missed the wire with the terminal screw.

Once they're all secure, I look at each connection with a loup I got from Fry's. Just a small one with an LED light on it. I make sure everything looks right and there's not a stray strand touching its wire neighbor. I caught that once.

Once I've done that, I'm confident everything is correct and secure from the altimeter to the bulkplate terminals. When prepping charges, I just focus on the e-matches. I did forget to list that on my rockets without redundancy (and for my L3) I'll check the resistance of the e-match with a meter.

Otherwise, I figure if I'm getting continuity beeps in my step 2 above and again at the pad, I'm good. Although double-checking everything certainly wouldn't hurt.

Yes! Got to check the resistance. Anything other than 1.0 - 1.2 Ohms for the matches I use and it goes in the waste pile. (Later, I'll touch it to a battery with leather gloves and see if it ignites before trashing it.)