High altitude

[John A. WilkeParticipant]

I don’t do anything different under 20K. Above that, I use two zip ties at each end (4 ties total per charge) just in case one ruptures. I would worry a wee bit about a hose clamp cutting a tiny hole in the tubing and if that happened, there would be problems. I always use brand new zip ties, not the old brittle ones.

With regard to the thicker walled tubing – I hooked one of the thinner wall tubes up to a water hydrant recently and it expanded from 1/2″ in diameter to perhas 6-8″ in diameter without breaking… I was amazed. As such, I don’t worry about the thinner stuff breaking, though it would be easier to cut with zip ties or hose clamps.

I’m with Ed on the falling hose clamps after I saw stuff from “Double Sixes” impacting the ground 😯 I sure don’t want to get hit in the melon with anything…

[SCOTT EVANS]

I just don’t want to get hit by one of your hose clamps falling from 10,000 feet.

I’ll be more worried about being hit by the rocket attached to the surgical tubing that was sealed with a tie wrap that gave way than a hose clamp. Haven’t you seen the Mythbusters show on the falling penny? Terminal velocity would prevent any significant damage from being done from a hose clamp.

Doug

A hose clamp has a hole in it. It would fall much faster than a penny. 😉

[muleParticipant]

Scott,
Terminal velocity is based on the weight and drag. Something that weighs little will have less downward force on it from gravity, so, no biggie. Here’s a cool NASA thread on it… http://www.grc.nasa.gov/WWW/K-12/airplane/termv.html

Adrian, what are the dimensions of the cardboard tubes are you using? Have you tried hot glue instead of epoxy?

[AdrianParticipant]

I use the 1/4″ launch lugs from Apogee for my charges. I make a 5-minute epoxy puddle on a piece of plastic, fold the wires of an ignitor 90 degrees and set the wires into the puddle with the head sticking straight up, and then put the cardboard tube around the ignitor into the puddle. Then when the 5-minute epoxy sets up, I fill the tubes with pyrodex and cap it off with more 5-minute epoxy. I haven’t tried a glue gun. These have been very reliable charges for me, using easy-to-get pyrodex and motor ignitors (the Quest Q2G2 ignitors are sweet for this application). I’m going to see if I can fit one of these cardboard charges next to my surgical tube charge for the apogee deployment in my high-altitude Balls shot next week, and fire it as a backup using the 4th output from my new Raven altimeter.

The only advantage of the potted cardboard tube approach over the surgical tube is that it packages a little smaller. They’re more of a pain to make. The size difference isn’t a significant advantage for bigger birds, but it’s helpful for 38mm and below.

[SCOTT EVANS]

Scott,
Terminal velocity is based on the weight and drag. Something that weighs little will have less downward force on it from gravity, so, no biggie. Here’s a cool NASA thread on it… http://www.grc.nasa.gov/WWW/K-12/airplane/termv.html

Adrian, what are the dimensions of the cardboard tubes are you using? Have you tried hot glue instead of epoxy?

SO……. What are you saying? Because I wiegh more than you, I might fall faster? However, with my big stomach sticking out, there would be more drag and that I might actually fall slower than you? 🙂
Lets see? Wieght to third power times waist size, divided by hight and the sqaure route of your in seam = 123.682 mph.
HEY your right Greg!

[Bruce R. Schaefer]

Watch out using glue guns… you CAN get the glue hot enough to melt the insulation of the e-match, thus causing a short. It will show continuity, but no bang. Bad day for all. Another good thing to do is check the resistance. No resistance means a short. A few ohms or so and you’re good to go.

[Steve JensenParticipant]

Someone mentioned Pyrodex (Pyrodex P I’m assuming).

Does it work with ematches (Quickburst home grown) and surgical tubing?

Getting 4F isn’t trivial.

Pyrodex is much easier to get, and you don’t have to order $125 bucks worth.

Yet, I’ve heard of some lawndart Pyrodex efforts…

[edwardModerator]

Tim at the launches generally carries the real stuff…I’ve not had a problem of late getting it – let me know.

Edward

[muleParticipant]

Scott,
I would kick your but falling, I have a lower profile belly. 😛 But, the screaming like a little girl all the way down may slow me some…. BTW, still waiting for the ins co to give us the $$$ amount.

Adrian,
so you leave any air space in there? When I run out of the little plastic cups I have, I want to try this method.

I didn’t think Pyrodex burned fast enough?????

I buy my 1lb cans of 4F BP from the Blunderbuss, Jim is a great guy and sells to rocketeers. Although I get my other supplies from him too, I shoot BP arms. 7080 W. Colfax. 720-207-2843 Call and make sure he has some first.

[SCOTT EVANS]

Someone mentioned Pyrodex (Pyrodex P I’m assuming).

Does it work with ematches (Quickburst home grown) and surgical tubing?

Getting 4F isn’t trivial.

Pyrodex is much easier to get, and you don’t have to order $125 bucks worth.

Yet, I’ve heard of some lawndart Pyrodex efforts…

I think Pyrodex would work. You need to bench test, and get the right amounts. 2F 3F and 4F all act a little different from each other.
I imagine some of those lawn darts were never tested.
You wouldnt stand in front of a gun, loaded with Pyrodex would you.
Last I checked, my 54 cal. Night Rifle, was pretty deadly at 150 yards on Pyrodex. 😯

[Author]

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