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 Working designs for parachute ammo (with a difference...) « View previous topic :: View next topic » 
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jackssmirkingrevenge
PostPosted: 12/03/2007 5:00 AM    Post subject: Reply with quote

space monkey
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Agreed - or, how about this, how about a solid epoxy cast around the elecronics? Naturally you'd need to leave the lens clear, and a downside might be overheating of the components. This would protect the components from being dislodged, though it would not guarantee that internal mechanisms (like within the lens itself) would not be damaged.
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BigGrib
PostPosted: 12/03/2007 5:13 AM    Post subject: Reply with quote

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Ok so theoretically with a 36" 1.5" barrel is 928.57 g's right at an acceleration rate of .01 seconds and a total velocity is 300 fps, what kind of spring would you want behind the camera rig to compensate for the acceleration, how much psi would you want the spring to provide, saying you're going with a spring, maybe a combination of the spring and a cushy break away sabot as well.
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Carlman
PostPosted: 12/03/2007 5:38 AM    Post subject: Reply with quote

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yea probobly shoud have added that it is a pnuematic cannon, 1.5m 40mm barrel (gb barrel)

Biggrib: i know u were figuring out the Gs all i was sayin is that most of the posts are about it lol

but thats a really good idea about the model rocket and combustion gun, mite hav to try that...

the spring might idea might work as long as you find the rite one.

solid epoxy cast, hmm i dunno seems like alot to do where there is simpler ideas.
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paaiyan
PostPosted: 12/04/2007 8:21 AM    Post subject: Reply with quote

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I like jack's epoxy idea. I don't think you'd need to worry much about overheating with a small camera.

And carlman, what other simple ideas might you be suggesting? No amount of foam wadding is going to keep it safe. I don't think a spring would do you any good either. You cast the electronics in epoxy and they won't move around, end of story. Besides, between epoxy and rigging a spring loaded strain reducer, if you think epoxy is the more difficult, I think you've got some issues.
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Carlman
PostPosted: 12/04/2007 8:36 AM    Post subject: Reply with quote

The Aussie
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i can assure you i have no issues so don't go having a go at me.

i was meerly saying that it may involve more than a simple spring rig. The camera would have to be wrapped in something to stop epoxy from going on it and then seat it perfectly straight in the epoxy and then you have to get the chute side of it going.

just because you have 1500 odd posts does not give you the right to flame me for saying what would be harder for ME.
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paaiyan
PostPosted: 12/04/2007 9:06 AM    Post subject: Reply with quote

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I wasn't flaming you, sorry if it seemed that way. And you don't put the camera in the epoxy, you put the epoxy in the camera. Epoxy is a very good insulator and won't short circuit anything. You put the epoxy on and around the circuits themselves. Think of it this way, if you're in a car wreck and wearing your seat belt, you can still die, because your internal organs bang around inside when you stop. Same thing with the electronics, so the epoxy keeps them from moving.

Obviously you can't put it where it would interfere with the optics, that's just something you're going to have to hope doesn't break. Heck, you can rig up a spring thing and use epoxy, even more effective. I'm just saying if I had to choose one to do, I'd go with epoxy, because it's a lot less work.
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Carlman
PostPosted: 12/04/2007 9:19 AM    Post subject: Reply with quote

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yea sorry paaiyan im a bit tense at the mo as of other reasons.

oh k i get it now, although it may be hard getting the camera apart (glued?)

im still deciding on what to do but that epoxy looks like teh way to if i can get into the camera, thnx JSR and paaiyan uve been gr8 helps Very Happy

nd yea sorry agen paaiyan
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paaiyan
PostPosted: 12/04/2007 9:23 AM    Post subject: Reply with quote

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It's all good. Epoxy is actually used in electronics quite a bit to cover sensitive things. I know there's a thumbdrive out there that's filled with it. Supposedly the most secure drive in the world, its filled with epoxy to protect form shock, and to make it nearly impossible to get at the electronics without rendering them useless.

You are right, not all cameras are made to be opened. But if you're talking about shooting it up in the air with a cannon, whats a couple nicks and small cracks in the case right?
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Carlman
PostPosted: 12/04/2007 9:33 AM    Post subject: Reply with quote

The Aussie
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yea tht drive would be useless to sum1 wanting to get at the info another way lol

yea supose, thn i can claim it under warrenty, or buy another that has nitevision Twisted Evil thl be fun
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paaiyan
PostPosted: 12/04/2007 9:39 AM    Post subject: Reply with quote

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Actually, the drive has hardware encryption that literally burns itself out after 10 successive unsuccessful password attempts. Of course my theory is, well, don't lose the drive.

And you're not likely to get any kind of warranty off the camera after opening it.

You: I want to get a replacement camera or my money back please.
Service rep: What's wrong with the camera sir?
Y: Well, I popped open the case, by the way you guys should make that a little easier, and tried filling it with epoxy so reduce shock and it just stopped working.
SR: So... You opened it and filled it with epoxy to reduce shock?
Y: Yes
SR: Might I ask what kind of shock
Y: I was going to shoot it out of a cannon. Man, you guys should make those things a little more rugged yea?

Yea. I don't think they'd let you have another one, haha.
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Carlman
PostPosted: 12/04/2007 9:54 AM    Post subject: Reply with quote

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i want 1 of those drives!!

tht is so funny, i shud do that and see if thts how it wud go down lol

but yea i can get just the cams alone 4 around 30$ aussie so yea i wud sacrifice 1 or 2 just to see the vids i get from it lol
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paaiyan
PostPosted: 12/04/2007 10:02 AM    Post subject: Reply with quote

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We want audio recordings if you try. Or I do anyway. I can guarantee they won't give you one, I just want to know what they say when you tell them that.

Also, I have an idea for a parachute deploy mechanism that might be effective, but I have no access to a drawing tool at the moment. I'm going to draw it on paper and upload it later.

EDIT: OK in the diagram I think the camera/spring is self-explanatory. The chute though. Pack it on top of a spring in a way that it will open when the spring ejects it. Use foil (?) to cover the end just strong enough that the spring can't break it. Lay a pyrotechnic fuse across the foil with a confirmed burn rate. Basically light the fuse, then inert it into the cannon. Fuse burns down, burns a hole in the foil, chute ejects. You can obviously put something between the chute and foil to prevent damage to the chute, and put wadding or something behind the projectile to prevent the compressed air from blowing out the fuse.

Just an idea, pleaswe feel free to ask questions, critique, and refine the idea. But if you make fun of my drawing, I kill you in your sleep.



chute-diagram.JPG
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chute-diagram.JPG


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BigGrib
PostPosted: 12/04/2007 13:51 PM    Post subject: Reply with quote

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I think you would need a drouge chute that will be able to handle any heat from a fuse or whatever
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jimmy101
PostPosted: 12/04/2007 15:08 PM    Post subject: Reply with quote

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You can buy a camera for Estes rockets that'll handle rocket's g-forces (a couple hundred g's IIRC). Might be able to handle a low power spudgun's g-forces.

Camera's have also been mounted on water rockets, which also pull a couple hundred g's at launch. Wouldn't be surpised if a google search on water rocket cameras turned up some pages on using a generic digital camera with no special g-force capabilities.

The tricky part isn't so much the camera mount, it is the parachute round. A para round not only has to have a way of deploying the chute but it also needs to be aerodynamically stable. If the chute pops out as the round is tumbling like crazy you may just tangle everything up in the shroud lines.

(Springs, padding etc won't do much to change the g-forces the camera experiences at launch. In order for a spring to have any significant affect on the g-forces the spring/padding would have to be longer than the barrel.)
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jackssmirkingrevenge
PostPosted: 12/04/2007 22:56 PM    Post subject: Reply with quote

space monkey
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Quote:
You can buy a camera for Estes rockets that'll handle rocket's g-forces (a couple hundred g's IIRC). Might be able to handle a low power spudgun's g-forces.


You can're really compare rockets to spudguns, the acceleration of a rocket happens over a much longer distance while a spudgun reaches maximum velocity in the length of a barrel. Then again, a spudgun might reach a lower maximum speed so it still would be a good starting point.

http://www.hammacher.com/publish/74349.asp

http://www.apogeerockets.com/Estes_Astrovision_Video_Rocket.asp
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