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Will this design work?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: dewey-1 » Wed Feb 01, 2012 11:17 am

I plan on doing a 3D model based on grumpyoldman design if he does not mind.
I have not drawn up a coaxial type design yet. Gives me something to do!
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Unread postAuthor: grumpyoldman » Wed Feb 01, 2012 11:27 am

The nerf gun looks really sweet. There's a lot of cool designs here. I'm sure it would work for t-shirts but the 1" and 1 1/2" qev's are too pricey for me.
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Unread postAuthor: grumpyoldman » Wed Feb 01, 2012 11:28 am

I don't mind at all, dewey-1. I got my ideas from all of you.
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Unread postAuthor: grumpyoldman » Thu Feb 02, 2012 7:43 am

Here's an updated design. I added the fin, enlarged the piston and exhaust. I wasn't sure how to fasten the fin, I just used steel clamps and a couple of nuts. I hope that is sturdy enough.
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Unread postAuthor: jackssmirkingrevenge » Thu Feb 02, 2012 8:12 am

OK, now you're talking :)

One small adjustment I would make is to have the rear of the barrel seal conical, in order to smoothen airflow to the barrel.
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Unread postAuthor: grumpyoldman » Thu Feb 02, 2012 8:34 am

Good morning Jsr! OK. Here's another one. I hope I don't have it on backwards.
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Unread postAuthor: jackssmirkingrevenge » Thu Feb 02, 2012 8:39 am

Exactly what I meant :) should work a treat.
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Unread postAuthor: grumpyoldman » Thu Feb 02, 2012 8:45 am

Thanks for all the help Jsr and dewey-1. I really appreciate it.

It'll be a week or two to get the parts in. When I start building, I'll post updates on the progress. Thanks again guys! SpudFiles ROCKS!
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Unread postAuthor: Technician1002 » Thu Feb 02, 2012 10:15 am

It is very difficult to get rolled up T shirts to fly 100 yards. They tend to turn sideways and quickly lose speed.

If you go commercial, check for potential patents on a launcher with a very similar shape and clear barrel.

Even with this much power, it is difficult to reach 300 feet. Yes the hole was made with nothing but a rolled up shirt tied with string while chronograph testing a design..
Image

Hitting the back row in the 300 section is possible.
Image
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Unread postAuthor: grumpyoldman » Thu Feb 02, 2012 10:39 am

Below is a picture of the Bleacher Reacher Pro, $1,600. Supposed to shoot t-shirts 100 yds. It uses paintball CO2 tanks. I'm tring to make something similar (also with a clear barrel), but a lot cheaper.
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Unread postAuthor: Technician1002 » Thu Feb 02, 2012 11:08 am

I've seen the claim, but have seen no documented evidence it reaches that far with a rolled up shirt. I've seen one in use. Typical use at a game is 100-250 feet. 300 yards may be a rare exception at high elevations in thin air, but not at sea level. They most often hit the 200 section up to the box seats, but rarely above that into the 300 section.

This is typical performance. The 300 section is not 100 yards.
[youtube]http://www.youtube.com/watch?v=83YKKXfmdlk[/youtube]

Another one
[youtube]http://www.youtube.com/watch?v=_0UcSZlWPv0[/youtube]
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Unread postAuthor: grumpyoldman » Thu Feb 02, 2012 11:25 am

I don't like false claims. :x That's typical in a lot advertising though. If I can get to 250 feet will be good enough. I can claim 300 feet too! But I won't.

When I get this thing built maybe I can tweak and squeeze out the remaining 50 feet somehow.
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Unread postAuthor: dewey-1 » Thu Feb 02, 2012 12:36 pm

After starting to do a 3D model of your design I came up against some problems.

With an output of nominal 1.5 inch port and and a port seal of 1.75 inches you will need at least a 2.5 inch nominal chamber and a 3.0 inch may be better.

Look at this drawing for a comparison.

This is why Tech is always stating use a larger diameter chamber that is shorter. Example is his use of propane tanks. Short and fat! :)
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Unread postAuthor: warhead052 » Thu Feb 02, 2012 12:38 pm

So you say you are trying to reach out for commercial use? Glad to hear I'm not the only one.

I would say your design would work, but you may have some problems with getting the tshirt to fly the distance needed. Try a light weight and soft sabot, like foam, to help get the acceleration, then have it peel apart almost instantly after leaving the barrel to avoid it hitting a spectator.
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Unread postAuthor: dewey-1 » Thu Feb 02, 2012 1:04 pm

You are limited by the "steel" sizes available and that being 2 to 1.5 maximum for higher pressures.

You can get larger in the 150psi rating standard pipe.
But then that becomes a "liability" issue unless you limit it to 150psi max.
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