# My project

#### MJR

##### C++ developer in the mix
Tutorial Publisher
Donator
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. :speakcool:

#### Nerull

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.

#### MJR

##### C++ developer in the mix
Tutorial Publisher
Donator
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 cock 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.

#### Eagle

##### The Amazing Flying Tuna Can
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.

#### RisingFury

##### OBSP developer
Should be around 43°. Just aim for 45°. There are plenty of other things you can improve far better then the 2 angle

#### MJR

##### C++ developer in the mix
Tutorial Publisher
Donator
Here are some pictures......

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#### Hielor

##### Defender of Truth
Donator
Beta Tester
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...

#### MJR

##### C++ developer in the mix
Tutorial Publisher
Donator
HA HA. Was that literal or a joke?

#### Bj

Donator
I am sure quite literal.

Please if nothing else, encase the whole thing in thick wood with at least a 6"- 12" clearance.

#### MJR

##### C++ developer in the mix
Tutorial Publisher
Donator
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.

#### Hielor

##### Defender of Truth
Donator
Beta Tester
But it really isn't as dangerous.
Famous last words by many thousands of teenagers.

#### Bj

Donator
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?:blink: #### MJR ##### C++ developer in the mix Addon Developer Tutorial Publisher Donator 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?:blink:
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.

Really expensive firework, wouldn't you say?:blink:
But if anything were to happen my dad is in the army.

#### Eagle

##### The Amazing Flying Tuna Can
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.

#### MJR

##### C++ developer in the mix
Tutorial Publisher
Donator
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?

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#### RisingFury

##### OBSP developer
No offense... but it doesn't seem *too smart* to be downplaying the danger, knowing it's there.

I take good precautions when starting my 6.5 ccm nitro engine by hand (such as double gloves and having someone hold the plane). I know a guy who lost 3 fingers when starting a nitro engine. Doctors managed to reattach two, but only one is functional.

#### MJR

##### C++ developer in the mix
Tutorial Publisher
Donator
What do you mean downplaying? I am not underestimating what could happen. Thats why I got more than one person helping me with the experiment. In another post somebody said to encase it with wood. Thats what I will do when I have time. Like I said, I am doing lots of school work.

#### Sky Captain

##### New member
Compared to my homebuilt 2,4 m diameter wind generator which disintegrated during the windstorm Erwin 5 years ago sending pieces of propeller blades flying all over the place at several hundred m/s this thing looks completely innocent.
Luckily it was night when my wind generator exploded so no one was outside and only property damage was broken window of neighbors garage. Otherwise it could have easily ended with someone seriously injured or even dead. Later I found 1 m long piece of blade that was penetrated more than half of its length into hard compacted ground as a testament of how violently this thing came apart.