Ejection Canisters – does anybody manufacture them anymore

[Paul Fecteau]

WOW….this is a really cool forum. Thanks guys for all the great feedback!

[John A. WilkeParticipant]

Seems like ground testing is mandatory.

So, I take it you had a lengthy set of wires from the alt-bay that let you feed the surgical tubing charge bundle in amongst the folds of your drogue section shock cord? (I know you don’t use an actual drogue)

Steve, I tie my wires off around the eye nuts (or lifting eyes or whatever you use) and that way the altimeter is not harmed during the charge. Strain relief is critical.

I’m glad to show you when I see you.

Tfish38’s method is the best you will ever see. We used this on our Q which got way up there… I’d use this to 50 or 60K, no worries…

[Warren B. MusselmanModerator]

I go by the calculation on the rocketry online calculator and add 25%-33% and have success every time. I used to ground test, then I decided since I always build using composites that going up a bit in size on the charge doesn’t hurt. I do ground test, but the neighbors start looking at me funny once the charges get bigger than 5 or 6 grams.

Warren

[Steve JensenParticipant]

I spent most of the morning into the afternoon building and testing ejection charges made as follows:

1) Quickburst ematches (from their kit)
2)Latex tubing Watts SLGE10 3/8″ x 1/4″ from Home Despot. It’s not cheap! I got 10 feet for $16.00
3) Cut tubing to 2.75 inch for 0.8 g BP charge. Bent over about 1/4 inch at end and sealed with CE (Commercial Electric) 4 inch cable ties. (About 1/8 inch width — no specs given — Again Home Despot.
4) Added BP.
5) Stuck in ematch.
6) Sealed with another cable tie to minimize air entrapment by just crimping tightly around the base of the e-match. See 3-dogs link above. Extremely beneficial.

Voila.

Spent a good part of the morning trying to seal the PML CPR system so I could test the altimeter. Got it to work once with shop vac to mimic flight (Perfectflite Altimeter). Major pain in the a$$. Last CPR unit I buy 😉 I hard wired for the other tests.

Results 0.8 grams blew off with force- Two nylon shear pins (2-56 screws from Missileworks.) The 1.2 gram sent the nosecone section into the neighbor’s yard as I’d neglected to attach the shock cord. I did put all the laundry in it… Had to barter with their dog to get it back — one hot dog for a nosecone.

This is for a quantum tube sudden rush.

Things I learned:

The Quickburst e-matches from their kit seem to work. I measured resistance on all 35. They were all on spec 1.5 to 2.5 ohms, except for one, which was low. I tried it and it worked anyhow. I made and tried 6 ejection charges per above. All worked flawlessly. They are loud, but not bad. A three gram up one (per Warren’s comment) will be quite loud.

I don’t know if this is a representative sampling (it’s not) but I will continue to use them.

Burned black powder smells awful I may play with Seven in the future. Three sets of tests also began to cause my pistons to begin to bind.

Sealing the CPR module is a pain. It seems to be the only way to test barometric based altimeters. (Adrian, does yours have a ground test sequence?)

Ground testing is beneficial. It familiarizes you with making your charges, your altimeter, hooking up the electronics, and understanding the steps needed top launch your bird.

Thanks to all the wise folks who chant ” Ground test, ground test, ground test!”

[Bruce R. Schaefer]

Burned black powder smells awful I may play with Seven in the future.

Personally, I love smell of black powder. L_S, you did good. 🙂 ALWAYS GROUND TEST… PERIOD.

P.S. I know, Warren, gotta scare the neighbors occasionally. 😉

[sserell]

Check out this experimental write up:

http://www.spacewarptechnology.com/SWT/High%20Altitude%20Tests/TABLE_CONTNETS.htm#experiment4

It has some good stuff in it. Of note was the failed deployment with “baggie wrapped” BP. I have had similar failures on ground tests where the BP burned through the edge of the baggie resulting in incomplete combustion and a completely burned through nomex shield. Tried it several times with bad results. Another guy also had a failed deployment at balls with a surgical tubing charge. Not sure whats going on but I suspect that sometimes if the ematch isnt centered in the BP and fires, its possible to have a burn through of the charge holder and the powder burns rather than explodes. I like the idea of a rigid holder where you can center the ematch and assure this doesnt happen. I know a lot of people have successfully used the tubing method without problems, but i’m a little suspicious…

[Bruce R. Schaefer]

I haven’t used latex glove fingers, though I’ve helped freinds fly rockets with them inside. No problem. I use a PVC end cap and a pyro tube. No problem with that either. 😉

[greywolves]

Hey guys,

If any of you are my neighbors sorry about that, hehe. I’m just glad i started small with the 0.5 gram charge. It looked like such a small amount too, #4f powder on the little white paper on the scale, just dust. So, I loaded up my Little Dawg, apogee charge, with the latexd tubing method. Used about 1 1’4 of tubing with igniter in the middle, one type on each side. BOOM! That little nylon 2-56 screw didn’t stand a chance, I even try to pull it apart, thinking i could break the screw with my Big muscles, hehe, no sir. So, yeah, I think i too like the surgical tubbing method, very easy.

Boom! 😈

[Mitch Smith]

ok, what size does most people use for the surgical tubing? 1/4, 3/8?

[edwardModerator]

I use 5/16″ ID x 1/2″ OD

Edward

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