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Backyard Rocketry Model, Amatuer, Experimental, and High Power Rocketry. Vehicle and Motor/Engine Design, Physics and Math, Fabrication, Flights, Testing and Evaluation. Share your rocket projects here!

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Old 04-26-2009, 05:18 PM   #1
MJR
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Default My project

Right now I am making a mortar tube that shoots out small projectiles. It uses washers, springs, dowels, PVC cement, PVC tubes, a hand made wooden frame, hinges, and etc. I'll put pictures up. Its actually kinda hard.
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Old 04-26-2009, 09:46 PM   #2
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Using PVC for anything holding pressure or experiencing shock (or worse - both at once) is a very bad idea. When it fails it turns into shrapnel. It's been mostly banned from use with compressed air for that reason.
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Old 04-27-2009, 01:42 PM   #3
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Lol. I cemented the PVC cap on the back. The dowel fits through. I put a string on the dowel to pull it back and :censored::censored::censored::censored: the launcher. The projectile is going to be fairly small so it is not that dangerous in my opinion. Anyway, after you let go of the string, the dowel flies up and hits the small projectile and launches it at multiple angles to see which one goes the farthest distance. It really isn't that bad. Like I said I'll show you pictures and diagrams.
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Old 04-27-2009, 05:00 PM   #4
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ABS plastics are a little more tolerant of impact than PVC fyi.

Though if you're just using a spring to propel the mortar, PVC should be just fine.

EDIT:

Oh, if the height of the exit of your tube and landing zone are the same the most efficient angle is 45 degrees (neglecting air resistance). With no air resistance angles the same displacement above and below 45 should be identical.

With air resistance, its better to aim slightly below 45. Exact physics will depend upon the ballistic coefficients of your projectile.
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Old 04-27-2009, 06:36 PM   #5
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Should be around 43. Just aim for 45. There are plenty of other things you can improve far better then the 2 angle
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Old 04-28-2009, 12:56 AM   #6
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Here are some pictures......

Last edited by MJR; 06-24-2009 at 11:15 PM.
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Old 04-28-2009, 01:10 AM   #7
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Originally Posted by MJR View Post
 Here are some pictures......
Make sure you have a video camera rolling when you use the thing, so we can all watch it blow up in your face...
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Old 04-28-2009, 01:11 AM   #8
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HA HA. Was that literal or a joke?
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Old 04-28-2009, 01:26 AM   #9
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I am sure quite literal.

Please if nothing else, encase the whole thing in thick wood with at least a 6"- 12" clearance.
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Old 04-28-2009, 01:28 AM   #10
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What do you guys think I am launching? 30mm rounds? My most dangerious projectile is a fore cracker with an extended fuse. Those fuses are like 3 sec. With a longer one it ais good enough. But it really isn't as dangerous.
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Old 04-28-2009, 01:32 AM   #11
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 But it really isn't as dangerous.
Famous last words by many thousands of teenagers.
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Old 04-28-2009, 05:57 AM   #12
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Quote:
Originally Posted by MJR View Post
 What do you guys think I am launching? 30mm rounds? My most dangerious projectile is a fore cracker with an extended fuse. Those fuses are like 3 sec. With a longer one it ais good enough. But it really isn't as dangerous.

Just so you know, a kid from my HS tried to make a firework. Granted he was stupid and was getting the gunpowder from .22 shells, but he didn't discharge static electricity, and well long story short, blew off his finger, and took a chopper ride to Seattle, which cost about $10,000...

Really expensive firework, wouldn't you say?
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Old 04-28-2009, 11:50 AM   #13
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Quote:
Originally Posted by Bj View Post
 Just so you know, a kid from my HS tried to make a firework. Granted he was stupid and was getting the gunpowder from .22 shells, but he didn't discharge static electricity, and well long story short, blew off his finger, and took a chopper ride to Seattle, which cost about $10,000...

Really expensive firework, wouldn't you say?
I suppose. Right now I am doing lots of school work so whenever I get to my little project I'll take safety precautions. Anyway, what do you guys think of it. Its one of my first projects.


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Really expensive firework, wouldn't you say?
But if anything were to happen my dad is in the army.
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Old 04-28-2009, 11:55 AM   #14
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Cherry bomb in an open pvc pipe isn't dangerous. Now if there was a projectile holding down the cherry bomb then maybe, but when it is the projectile, no biggie.

Just don't be a complete flap and get yourself hurt.
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Old 04-28-2009, 12:00 PM   #15
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I won't. I am a lot smarter than I seem. Intelligently and knowledgeably. Anyway, what is a good projectile to launch in your opinion?

Last edited by MJR; 04-28-2009 at 12:16 PM.
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