Ejection Canisters

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Jan 27, 2009
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Folks I am building my first rocket with Electronics (HyperLOC 835), I get the whole e-bay, altimeter setup with the exception of what types of ejection canisters to use and where to secure them/how.

I see many people use those centrifuge vials but were to mount them??? what is the typical setup here, does anyone have any pictures?
I just make a little packet of masking tape that contains the BP and e-match head. It just hangs from the end of the wire. I usually place it just above the motor (for apogee) and under the chute (for main). The pop is non-directional so you don't have to worry about blowing a hole in your airframe.
You can get canisters from Newtons3r Rocketry, Pratt Hobbies, and Quickburst (as a kit). I typically use a small section of a PVC pipe and an end cap mounted to my ebay. I have also used a small section of copper tubing for small diameter body tubes. I have also done something similar to Rocketjunkie, but I use the fingertip of a latex glove to keep the BP and ematch togehter. There are lots of different options. Just make sure you ground test!
I mostly use those plastic vials, and just leave them hanging in the chute bay. It doesn't pose a problem. It's always important to make sure the BP cant move around- and away from the ematch- the way i do that is with a wad of tissue packed in on top and secure the lid with some tape as an extra precaution.
It's easy enough to make your own - just be sure the Avionics bay is properly sealed away from the corrosive gas of the charges. I've used glove finger tips; ignitor tubes sealed with hot glue and dog barf; PVC caps; even the bowl from a pipe I got a a head shop. Definately ground test.
I am cheap and as such so are my ejection charges!LOL
I use Christmas lights and a length of Mickie D's drink straws..

Steps I do to make one:
1) Cut wires from string of lights(they should be about 6-8" long
2) Carefully 'snip' off the tip of the bulb(test first with a 9 volt battery to make sure the filament is good..do this BEFORE snipping off the tip!)
3) Cut about a 2-3" section of drinking straw, slide over bulb and wrap tape around it and the laight base
4) Measure out the BP and fill the straw
5) Wrap tape around the end to form a cap..

I have a umber of strings of lights that don't work as they should but the bulbs are still good..I attach them directly to the altimeter and tape the charges to the bulkheads..
Here's my first dual deploy ebay from my Lvl 2 project.
I used the small ejection canisters from Newton's 3rd. I shortened and terminated the ejection canister wires to a solid wire terminal on the outside bulkhead plate. Make sure you seal all penetrations and holes in the bulkhead.
I left some slack on the wiring of the ejection canister and wrapped several turns at the base of eyebolt.
The ejection cansisters are secure and eliminates the need for mount PVC caps I've seen elsewhere -- it was getting too crowded on the bulkhead.

ebay midway.JPG

EBAY assembled.JPG
I'm cheap too. I just take some plastic wrap, fold it over, and make a well with a finger. This is filled with BP and a home dipped ematch, and wrapped with masking tape to hold it together. In one rocket, I just fold the packet in a small piece of nomex to contain the residue a bit. On another I stick the plastic wrap/BP/match packet in a PVC cap on the bulkhead, and tape over it. I find the cap also contains some of the residue, though is really not necessary. Both methods have worked well for me.

ebay cap.jpg
The Newton's 3rd cannisters are great and reliable but in my experience they have a tendency to become brittle when they blow. Maybe it's the heat. They have knocked paint off the outside of two of my rockets, created visible dents and the inside is pretty scarred. The shards after use are hard and sharp. Some duct tape around them might limit the internal damage, or maybe wrap a fold of nomex around them to catch the slivers.
Thanks folks, lots of great ideas, the christmas lights are cool but I have so many problems getting them to light on my house, I am not sure I want to chance it with my rocket :) Though that does get one around the e-match dilemma.

Thanks for the pics as well, I will post my build thread later, I am sure y'all will not be short on advice :)
Xmas lites are very reliable and easy to use. Perfectflite actually sells them in a kit for BP use on their site and recommends them. And it DOES eliminate e-match hassles. I have used them myself, no problems.

www.perfectflite.com products......ECK-6 There is an online manual, tells how to make and use them on same page.
I use the Christmas lights too. I use two bulbs in parallel, just for redundency.

I use 400 grit sand paper on the bulb leads to take any dirt and oxidation off.

Break each bulb and use a small pointed tweezers to pull the wrap of wire off the base of the filament posts. This is what allows current to flow through the bulb after the filament burns out so the rest of the bulbs in the string stay lit. If you don't remove this, the bulb will still show a few ohms resistance even if the filiment is open.

Check continuity of the bulbs.

Then hot glue the bulbs side by side on a 2" x 3" piece of paper. Use a size large enough to make two to three wraps and long enough to hold the size charges that you need.

Wrap the paper around the bulbs and hot glue it together.

Twist the leads together with some 24 ga wire and solder each set of leads to the wire.

Fold each wire and lead along the side of the tube and put several wraps of tape around the wires.

A put hot glue in the end to cover the bear wires and seal the tube.

When ready to use, pour in the measured amount of BP, fold over the paper and add a piece of tape to hold it down.

These are a little bit of a PIA to make, but you can make a large number at once. Just complete each step on all the bulbs before going on to the next.