Ejection Canister

Please give your opinions about the different types of ejection charge canisters and where they can be purchased. Thank you.

My favorite ejection canister is a thumb from a latex glove, or a pinky for a smaller rocket... wrap it with electrical tape a few rounds and your good as any lunky "bowl" on your avbay.

I either tape it to the quicklink gear on my avbay, or if there is sufficient all-thread i tape it to there.

some guys in our club use silicone tubing, I have found this harder to seal. basically zip ties on the ends to "pinch" it off.

But if you must. these are cool i think..
https://www.blastcaprocketry.com/

I got blastcaps and just ordered some from rocket warehouse. For me the blastcaps look awesome on the av bulkplate!

https://www.rocketrywarehouse.com/
https://www.blastcaprocketry.com/

BTW
Great customer service from both of them.

I like the ejection canisters from Newton's 3rd.

https://www.newtons3rdrocketry.com/shop/index.php?cPath=25

You don't need an e-match when you use one of them.

I also often use the plastic wrap method described at the bottom of the page at:

https://www.info-central.org/?article=302

The plastic wrap method is inexpensive, quick, easy, reliable, and it handles prety much any size ejection charge.

-- Roger

Spent Estes 13mm motor casings. Bore out the nozzle just a little to let the ematch wires pass through. Bend the ematch head over so it'll contact the BP, then pass it in, wires first, until it's down in there. Hot glue and masking tape to seal off the bottom end.

Works best if you're one of us tolerant and diverse guys who flies little BP LPR rockets as well as HPR DD Js and Ks.

I use the 13mm motor trick but my favorites are the PVC canisters Mark describes in his book. They work really well for me. I use Pyrodex so I need the containment they provide. I pack paper towel in on top of the pyrodex and then use masking tape as the final seal.

PP

In my Wildman Jr., I didn't have room for canisters on the ends of the avbay, so I use small plastic centrifuge tubes with a tiny hole drilled in the bottom to accept a Q2G2 igniter. Fill it with pyrodex, snap the cap shut, wrap with 2-3 layers of electrical tape, and it's good to go.

On my last project (4" diameter tubefin), I made my own canisters similar to the "BlastCaps". These things are pretty easy to make if you have access to a metal lathe. Plain old 6061 aluminum barstock works fine. I incorporated a hole and wire slot in the mounting surface of mine, to accept the Q2G2 (using the included straw for strain relief and added insulation).

I made them the same OD as an AT 29/38 mm forward closure ejection well. That way, I can use the same snap-on plastic caps to seal them, rather than messing with multiple layers of tape.

Well I'd have to say The Blastcap is the way to go Never replace another charge canister again.

www.blastcaprocketry.com
​

For small ebays in the 54 mm to 75 mm range, I started using .38 or .44 caliber shell casings. Epoxy them to the bulkhead with JB weld, drill a small hole in the base of the casing for a Q2G2, fill it up with BP and tape off. These casings will hold about 1.5 grams of BP. I saw another TFRer not named Callahan use these but can remember his name.

Gary,

One more option to consider is copper pipe (two foot sections can be purchased at Home Depot or other hardware store). I have used sizes between 1/4" diameter (for 54mm to 2.6 dia. airframes) up to 3/4" diameter (for 6" to 7.5" dia. airframes) and they can be cut to length to match your av-bay application/amount of powder needed. To make it ready for use measure appropriate length, cut with a pipe cutter, scuff up one end, fill that end with about a 1/4" of epoxy reinforced with milled/chopped fiberglass and/or even a swatch of fiberglass, and finally drill an 1/8" (or less) hole to thread the e-match lead through. The charge canister is held in place by a copper cap (also purchased at Home Depot) with another 1/8" hole drilled in the side to route the e-match lead to terminals or directly into the av-bay. I have included a picture of on such charge canister in progress (epoxy just poured into fill bottom) and an av-bay bulkhead utilizing one of the canisters.

I went to this method after having trouble with the PVC (I was tired of them cracking and having to replace them). Also I preferred this method because it takes less bulkhead space than an equivalent volume PVC canister. But, unlike Gary T.'s Blastcaps, this solution does require periodic maintenance as the epoxy plug every so often will crack or pop out (maybe one every 8 to 10 flights), but it is simple enough to replace the epoxy plug versus having to find and cut a new section of PVC.

-Tim

while we are on the subject I really quickly wanted to ask how you keep your bulkheads so clean? iv used mine once and they are covered in soot that without actually using sandpaper won't come off? Tim yours seems to have some sort of glossy finish. idk.

For ejection canisters I use some 1"aluminum pipe cut in 1.5"long pieces then epoxy them to the bulkhead

bandman444 said:

while we are on the subject I really quickly wanted to ask how you keep your bulkheads so clean? iv used mine once and they are covered in soot that without actually using sandpaper won't come off? Tim yours seems to have some sort of glossy finish. idk.

For ejection canisters I use some 1"aluminum pipe cut in 1.5"long pieces then epoxy them to the bulkhead

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My guess is THAT bulkhead is a "virgin"

if you want them clean, don't launch them

but like on the blast cap site they show a bulkhead the said has been through 10+ flights and it looks spot less. so what I'm hearing though is that that is not the case

bandman444 said:

while we are on the subject I really quickly wanted to ask how you keep your bulkheads so clean?

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GRIFFIN is right, the one shown above is a virgin one, but attached is a "dirty" one. I keep them clean by coating the bulkhead with epoxy when building and more importantly fairly quickly (usually the evening after a launch at the latest) wiping the whole bulkhead and all hardware down with a cloth dampened with Break Free CLP--best stuff you can buy for cleaning and preserving your motor hardware and also helps keep your bulkheads, et. al. from corroding.

Take it from a servicemember that uses the military grade CLP all the time. That stuff works! Out at sea, the topside mounted 50cal machine guns get a coating of CLP every few days, and they withstand the constant saltwater spray with no problem.

For ejection charge canisters, I've used all sorts. I used to snip the corners off the reload bags. Fill with BP, insert ematch, tape and go. Now I use the little centrifuge canisters from Aerocon. On my L3 rocket, I use something similar to the Blastcaps. I have access to a machine shop, so I made 'em myself. But I wouldn't hesitate to recommend buying them from Gary. He's a great guy, and they make your av-bay look gorgeous.

bandman444 said:

but like on the blast cap site they show a bulkhead the said has been through 10+ flights and it looks spot less. so what I'm hearing though is that that is not the case

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It IS the case as thats my Av-Bay, One its G10 which cleans better than untreated wood. After every! launch I spray it with a degreaser and clean it with a plastic or brass detailing brush, I then spray it again with WD40 hit it again with the brush then wipe it down with a clean rag. Anyone who knows me can tell you I'm very anal when it comes to my rockets, I maintain my Av-bays after every launch. Here are a bunch of my other Av-Bays ranging in size from 2.1, 3, 4, 5 & 6" The 4" is the one on my site which in this pic has an additional 5 flights on it since the site pic was taken. Also this a redundant Av-Bay which has 2 charges go off on each end per flight.

For size comparison the 2.1 & 3" have the small Blastcaps, The 4" are the medium Blastcaps and the 5 & 6" are the large Blastcaps.

GaryT said:

For size comparison the 2.1 & 3" have the small Blastcaps, The 4" are the medium Blastcaps and the 5 & 6" are the large Blastcaps.

View attachment 37392View attachment 37393

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Gary what are all the blankets, socks and foam? It's like you line 'em up and tuck 'em into bed every night :wink:

Dang straight lol, Alls it takes is one lose or broken wire and you got yourself a lawn dart. Also the way I do my Av-Bays is that each one of those fits ALL my rockets of its size. The 4" fits ALL my 4" birds and so on. Plus some of the smaller ones fit bigger birds as well. the 2.1" also fits all my 2.6" birds. But thats another thread. Buy the Blastcaps All the best dressed Av-Bays are wearing them

I would have to say the blast cap is the Cadillac of the ejection canister world. They even come with the hardware to install them.

I used to make my own with flashbulbs, cardboard tubes and a hot glue gun. These days, Pratt hobbies are tough to beat at $2
each: https://www.pratthobbies.com/proddetail.asp?prod=WEC-5B - I keep a bunch of each size in my field kit just in case. Anyone have experience with glow plugs?

alexzogh said:

I used to make my own with flashbulbs, cardboard tubes and a hot glue gun. These days, Pratt hobbies are tough to beat at $2
each: https://www.pratthobbies.com/proddetail.asp?prod=WEC-5B - I keep a bunch of each size in my field kit just in case. Anyone have experience with glow plugs?

Click to expand...

I'd like to say that Pratt's ejection cannisters are quite reliable and handy. I make my own with vinyl tubing and cap it with hot glue. It works fantastic.

alexzogh said:

I used to make my own with flashbulbs, cardboard tubes and a hot glue gun. These days, Pratt hobbies are tough to beat at $2
each: https://www.pratthobbies.com/proddetail.asp?prod=WEC-5B - I keep a bunch of each size in my field kit just in case. Anyone have experience with glow plugs?

Click to expand...

With those canisters, do you just tape them to the top of your bulkhead? Or do you let them sit loose? With all the other canisters, they are physically mounted to the bulkhead, but these look completely disposable.

Yes, they are completely disposable. I have a second piece of g10 that sits over the top of the AV Bay. I usually just tape it to there. I've also sewn some nomex pockets that have worked to varying degree's.

I should say, in larger rockets, I use a traditional canister.

I have used he pratt hobbies canister with a brass end cap. I use the end cap as a place for attachment.

Hi all,

I have a bunch of the WEC-5A from Pratt Hobbies. Have had them for a while and was gonna use a few up. Just to be sure, I ohm'ed them to about 5 to 6 ohms. Sound about right to you? These are filament style not chemical matches. My Black Sky HiRis and Old match based Pratt canisters alway ohm out to 2 and 2.x ohms respectively.

My Pratt BEC-5A are before he took to writing the resistance on the canister.

Thanks for any info.