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Pressure Amplifier Spud Launcher?

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Pressure Amplifier Spud Launcher?

Unread postAuthor: PeteS » Wed Oct 09, 2013 8:56 am

I have been thinking of building a launcher that works like a pressure amplifier, basically a two stage launcher. It would consist of two chambers connected by a push rod. The first chamber would be a fairly large and low pressure PVC chamber and might be either combustion or pneumatic. It would drive a push rod until the end of the stroke where the pressure would be dumped as the piston went past a port. The push rod would drive a piston in a much smaller diameter steel chamber. There would probably be a burst disk between the high pressure chamber and the barrel.

According to a quick and dirty calculation, it looks like a 3" primary chamber with 100 psi using a push rod to drive a 1" piston you would get something in the neighborhood of 400 psi. More or less amplification would seem to be easy to arrange by selecting the appropriate diameters.

Does this sound like it would work?
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: jrrdw » Wed Oct 09, 2013 9:09 am

Does this sound like it would work?


All though anything is possible I think you should ask yourself are you willing to dedicate to time and funds to such a complicated project...
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: jackssmirkingrevenge » Wed Oct 09, 2013 9:11 am

A fridge pump is a cheap and easy way to achieve higher pressures without the need for such complexity, and if you go hybrid then the world is your perforated oyster ;)
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: PeteS » Wed Oct 09, 2013 9:32 am

It doesn't sound all that complicated to me, but maybe I am missing something. One likely advantage I can see is that it could be used with no pump, powered purely by combustion. That way you would not be tied to an electrical power source. You would only need the launcher, some spuds, some burst disks, and your propane metering system. So only a few pounds of stuff that would all fit in a small backpack.
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: jrrdw » Wed Oct 09, 2013 9:39 am

PeteS wrote:I have been thinking of building a launcher that works like a pressure amplifier, basically a two stage launcher. It would consist of two chambers connected by a push rod. The first chamber would be a fairly large and low pressure PVC chamber and might be either combustion or pneumatic. It would drive a push rod until the end of the stroke where the pressure would be dumped as the piston went past a port. The push rod would drive a piston in a much smaller diameter steel chamber. There would probably be a burst disk between the high pressure chamber and the barrel.

According to a quick and dirty calculation, it looks like a 3" primary chamber with 100 psi using a push rod to drive a 1" piston you would get something in the neighborhood of 400 psi. More or less amplification would seem to be easy to arrange by selecting the appropriate diameters.

Does this sound like it would work?


If your going with this idea you will need a few different valves built into the system and at least 1 regulator. That alone elimates any kind of simple combustion.
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: jackssmirkingrevenge » Wed Oct 09, 2013 9:55 am

PeteS wrote:It doesn't sound all that complicated to me, but maybe I am missing something. One likely advantage I can see is that it could be used with no pump, powered purely by combustion. That way you would not be tied to an electrical power source. You would only need the launcher, some spuds, some burst disks, and your propane metering system. So only a few pounds of stuff that would all fit in a small backpack.


There has been some discussion of such systems, here's a diagram I had posted a long time ago:

Image

No real advantage in using it as-is though, for real advantage you would need the piston on the compression side to be of smaller diameter in order to generate significantly larger pressures than what the combustion is achieving.

That being said, I'm sure there's room in your backpack for a small bicycle pump - go hybrid, you won't look back!

High pressure pneumatic:

[youtube]http://www.youtube.com/watch?v=lXnh3-uNDLU[/youtube]

Same ammunition from a hybrid:

[youtube]http://www.youtube.com/watch?v=WAYASFZvRLo[/youtube]
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: PeteS » Wed Oct 09, 2013 11:54 am

Hybrid indeed may be the way to go, but it seems to me this would be pretty simple and work. The line in the barrel a burst disk
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Re: Pressure Amplifier Spud Launcher?

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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: jackssmirkingrevenge » Wed Oct 09, 2013 1:15 pm

I predict it will be a lot of effort for little performance gain, but that's just my view, if you believe you can prove the naysayers wrong go ahead and build it and let us know how it goes ;)
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: jrrdw » Wed Oct 09, 2013 1:53 pm

if you believe you can prove the naysayers wrong go ahead and build it and let us know how it goes


In short, he dares you! :P

naysayers ='s jrrdw :twisted:
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: Solar » Thu Oct 10, 2013 1:35 am

What about efficiency benefits regarding the difference between decanted air and the volume of air pressure created from a metered combustable source? I think the old Tippmann paintball gun that used propane claimed something like 3000 shots from a single bottle.

https://www.google.com/search?q=tippman ... ewt7fxM%3A
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: jackssmirkingrevenge » Thu Oct 10, 2013 3:55 am

jrrdw wrote:In short, he dares you! :P


Not quite - but certainly the last thing I want to do is discourage research and development on this forum! I remember back in the days of spudtech when I had started playing with bicycle shock pumps, most people thought I was going to blow myself up - and look where we are today :D

What about efficiency benefits regarding the difference between decanted air and the volume of air pressure created from a metered combustable source?


The same reason that cars that run on gasoline are more efficient that something like this. Clearly chemical energy is a high density source - you could also argue that the chemical energy stored in one's body combined with a stirrup pump would be an easier way to achieve high pressure ;)
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Re: Pressure Amplifier Spud Launcher?

Unread postAuthor: Technician1002 » Fri Oct 11, 2013 10:25 am

I've had good luck simply using a sabot. This can take the force of a large area and apply it to a small dense projectile. This was done in a thread for the max damage to a AA battery.

http://www.spudfiles.com/spud-cannon-related/topic21827.html

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