Get some LOC 1/2" launch lug maaterial and cut it into various lengths. Then cut some 1/2" dowel into thin strips (making itty bitty bulkheads). Epoxy the "bulkheads" into the end of the LOC tube.

After the epoxy is dry, drill through the wood to allow an ematch to pass. Stuff the other end with paper towel and use masking tape to seal 'em up. I've flown some of these 40 times. They work splendidly and are very reusable....

Hi everyone,

I was going to try using the surgical tubing method. Should i use a cannister or something more stiff to hold the tubbing, for more of a direction to the charge? any thoughts?

Thanks

Jon Skuba sells aluminum machined charge holders - might want to get in touch with him.

I just let the surgical tubing hang out in the rocket. Usually though it is packed tight against the bulkhead because the shockcord is crammed on top of it and it cannot move.

3dogs suggestion works great.

I slide the canister into a 1/2 PVC coupler glued to the ebay with a
notch cut in the side for the wires. It holds it in place very well.

Last year I tried the surgical tube method on my 4" and up rockets. I glue some velcro to the top of my ebay, I have some glued to the tube. it
stays in place well.

It being placed a top of the ebay gives it only two directions
to go,,,up and out.

Both ways have worked fantastic for me. Both learned from
NCR members who have used them for some time.

I still use my xmas bulb igniters in both.

Duel deploy is great fun. Good luck.

If your not going too high, fingers of a latex glove and pop ties work.
I have a rocket loaded and ready to go next launch with this.
Over 20,000! Ask the dog guy!
I have used pvc caps too.
Lots of didderant ways!

After the UprOar Project (see photo gallery) and a number of other rockets since then, I'm 100% committed to using the surgical tubing method. Cheap, disposable and VERY reliable if you use quality zip ties to seal the ends.

Warren

Thanks Warren, it appears to be a solid technique.

Does it take any additional BP to overcome the tubing package?

I have a 54mm bird and I've calculated I need about .5g of powder to get it out. (I am ground testing!)

I also notice that people put two ties per end of the tube unit. Is this your technique?

go here http://www.wimpyrockets.com/page16.html and always ground test...

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)

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

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...

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

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!"

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. 😉