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Coaxial barrel ports

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Coaxial barrel ports

Unread postAuthor: aturner » Fri Mar 04, 2005 1:48 pm

Here's my crazy idea for improving a coaxial combustion spud launcher. This essentially should have an effect that is similar to a burst disk, b/c it should allow just a bit more time for pressure to develop before the spud is launched. There are three images to show my idea:

This is a standard coaxial. Nothing fancy here.
<img src="http://loose-cannon.home.mindspring.com/spudbreech1.jpg">

This is a standard coaxial, but with "ports" drilled into the side of the barrel. The arrows show the location of these ports. The ports are sealed by the potato at first. Then when the launcher is triggered, the potato begins to slide and this opens the ports. However, I do not think these ports will improve performance in this situation b/c the full flow of the combustion can already move in through the rear of the barrel.
<img src="http://loose-cannon.home.mindspring.com/spudbreech2.jpg">

Now THIS is my actual idea for improving a coaxial spudgun. After loading a spud, I would add an endcap (not glued, but just friction mounted) to the rear of the barrel. The endcap has a SMALL hole drilled in the center, to allow some of the pressurized gas from combustion to pass through. The idea is that the small hole in the rear will first limit the amount of pressure, but then as more pressure builds and the spud slides forward, then the side ports will be opened, allowing the full flow of the combustion reaction to propel the spud.
<img src="http://loose-cannon.home.mindspring.com/spudbreech3.jpg">

This design will definitely not work in a launcher with a low C:B ratio, like 0.8:1. However, I think it might help in a launcher with a higher ratio, such as 1.5:1, because it might help harness more of the available pressure.

Really, this should work in any launcher that "wastes" lots of energy. So this concept might also work in a hybrid at a low mix. Maybe it would allow for no union or burst disk?

But the only way to know is to test it. Maybe soon....

p.s. I proposed this idea to the spudtech forums many months ago, and received some good responses at the time. I'm now re-visiting this idea because I'm equipped to actually test the idea.
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Unread postAuthor: spudshot » Fri Mar 04, 2005 4:36 pm

hey, that's a good idea, i'll have to try that once i get my parts from joel
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Unread postAuthor: jdp204 » Sun Mar 13, 2005 8:41 pm

that may casue an explosion though. :oops:
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Unread postAuthor: spudshot » Sun Mar 13, 2005 9:28 pm

i dont think so, people have close chamber tested their launchers before with no problems
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