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Archimedes' cannon

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Archimedes' cannon

Unread postAuthor: jankokes » Thu May 18, 2017 8:57 am

Hello,

I didn't want my (re)discovery and adjustment to be forgotten, so I publish it here and now:
ArchimedovoDelo.png


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I suppose there were problems in ancient times regarding materials. The cannon was probably never fired with a bullet. However it seems probable it was used as a flame-thrower, which was being used and we have no idea what it looked liked and how it worked. Today it could be used as an external combustion engine. The L-pipe going into the wax was added by me, it results in higher steam pressure. In true Archimedes' cannon it would be cut short and sealed.

Jan Kokes
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Re: Archimedes' cannon

Unread postAuthor: jackssmirkingrevenge » Fri May 19, 2017 8:27 am

The chipmunk myth busters had a crack at this, have you made a prototype or is it just a concept? In the modern world there are certainly more practical ways of achieving high pressure.
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Re: Archimedes' cannon

Unread postAuthor: jankokes » Fri May 19, 2017 1:36 pm

I have seen the principle in action as a child. It was at camping site fire, at which a can of paraffin wax was resting and heating up. After the wax spontaneously ignited it was allowed to heat up some more, and than a can of water on long handle was poured into it. The result was mushroom shaped fire column about 6 meters high. And this was not even injection, just a pour! (one video I just googled is here: https://www.youtube.com/watch?v=1NTzcSEhgJM)

I have read about the reconstructions of cannon of Archimedes, however each one of them failed (except for the MIT guy, but that was DaVinci's cannon, not Archimedes'). When I saw pictures I added one and one together, along with the mysterious flame thrower, and it all of the sudden became clear.

As a side note, this is not about achieving higher pressure in muzzle. It is about higher pressure in purple area which injects water with greater speed into the wax. As with any project on this site this is about light gas, meaning light in comparison with products of gunpowder combustion, which allow greater projectile speed at given pressure, or same speed at lower pressure.
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Re: Archimedes' cannon

Unread postAuthor: jackssmirkingrevenge » Sat May 20, 2017 6:22 am

jankokes wrote:[url=And this was not even injection, just a pour!]https://www.youtube.com/watch?v=1NTzcSEhgJM[/url])


Image

As a side note, this is not about achieving higher pressure in muzzle. It is about higher pressure in purple area which injects water with greater speed into the wax. As with any project on this site this is about light gas, meaning light in comparison with products of gunpowder combustion, which allow greater projectile speed at given pressure, or same speed at lower pressure.


Interesting indeed. Do you have the material facilities to contain the forces involved? I can imagine a very "steampunk" looking looking device made mostly of brass and copper with gauges everywhere.
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Re: Archimedes' cannon

Unread postAuthor: jankokes » Sat May 20, 2017 9:56 am

jackssmirkingrevenge wrote:Do you have the material facilities to contain the forces involved?


Not yet.

jackssmirkingrevenge wrote:I can imagine a very "steampunk" looking looking device made mostly of brass and copper with gauges everywhere.


That would be super cool, albeit steel seems more practical. I designed extra fast valve for starter:

valve.png


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Top of the vertical pipe and one side of the horizontal pipe are connected to the (same) pressure tank. The vertical pipe never allows the pressurized medium to pass through, however it does allow for the piston (blue) to move freely. The piston of closed ventil (cutaway view) is held in place by wedge (brown) which is held in place by trigger (purple). Once the trigger is pulled (full view) the piston shoots down powered by pressurized medium above. That opens horizontal pipe to allow for the pressurized medium to pass through.
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Re: Archimedes' cannon

Unread postAuthor: jackssmirkingrevenge » Sun May 21, 2017 7:43 am

Consider a lever instead of a pull pin to release the mechanism, as the friction from the force of the "pressurized medium" will make it difficult to open.
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Re: Archimedes' cannon

Unread postAuthor: jankokes » Mon May 22, 2017 4:14 am

jackssmirkingrevenge wrote:Consider a lever instead of a pull pin to release the mechanism, as the friction from the force of the "pressurized medium" will make it difficult to open.


OK, little clarification. By "connected to the (same) pressure tank" I meant the inlets can be, but don't have to be, connected to the same tank. In Archimedes-me cannon there are two areas with high pressure. One is the purple area of steam at the top of the first picture. There isn't that much of a pressure there before the cannon is shot, and it is this pressure that the pin holds. Second pressure area is inside the cannon. There will be much greater pressure there and also in the steam area once the pin is pulled:

CxHy(l) + H2O(l) + heat -> H2(g) + CO(g)

Two liquids turn into two gasses almost instantly, resulting in rapid increase in pressure. However this pressure won't interfere with the pin because the pin won't be engaged any more. The design can incorporate lever trigger of course, there is nothing easier, and I thank you for the suggestion:

paka.png
paka.png (26.86 KiB) Viewed 470 times


I originally thought that I would pull a string attached to the eye of the pin, but tying string to a lever will be just as easy. I want to stay clear when the cannon goes boom.
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Re: Archimedes' cannon

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