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[alway]

This morning I had an interesting idea for a new type of magma cannon. This variety is quite a bit different from the original pump variety; primarily in that pumps are not required, although they help quite a bit. The mechnism uses a collapse of a natural wall/floor into a pool filled with magma. The magma then 'splashes' up and out; I currently do not have a working cannon, but I am testing various methods with which it could work. At the very least, they could be used as large, multi-tile magma landmines. I am currently testing various setups, and will post more info as it comes in. 

And here is the video proof of concept: http://mkv25.net/dfma/movie-1487-magmacannonv20proofofconcept

Now the problem is... Figuring out how to weaponize it. I am thinking something perhaps like this:

Code: [Select]

FHFFFFFHF
WLLLLSLLW
WLLLLSLLW
WWWWWWWWW

S=support linked to lever
F=natural floor tiles
W=walls
L=magma/lava
H=hatch
So questions which need answers:
1: can the magma jet be redirected
2: will natural walls at a much higher elevation increase the height of the jet
3: will more z levels of lava and/or walls result in a higher jet

Answers from experiments:
2: No, it only goes up 1 z level, unaffected by height of fall
3: Yes! Using an experiment with 2 z layers of lava and 2 z layers of magma resulted in a 2 z layer jet of magma. However, more testing is required to find out if 1 floor and 2 layers of magma have the same results (2 walls and 1 magma wouldn't change the results, judging by the way it seems to work (displacing the magma it goes through).

I think I'm done testing for awhile, but I may add more later. By the way, does anyone have any suggestions for a possible way to redirect the magma jet? On another note, the pool of magma underneath should be pump "pressurized" if you want the magma to stay up above the pool like it does in my video.

Also, if you use 2 layers of wall (2 floors, 1 wall) you should be able to have the same effect as if you pressurized the pool (magma staying up) which with some tricky engineering could possibly be used to move small quantities of magma upward without any pumps required at all; mostly of use in deep pipes w/o bauxite to get the magma closer to the surface for forges/furnaces. The amount of magma moved seems to be 7/7 blocks of equal size as the dropped material (so with simple floor and 1 layer of magma you get 1 7/7 tile per square dropped down).

[Martin]

I think I'm done testing for awhile, but I may add more later. By the way, does anyone have any suggestions for a possible way to redirect the magma jet?

I think it needs to be determined if there is any conservation rule here. That is, if you displace 63 units of magma (a 3x3 pool of 7 deep magma) do you get 63 units of splash? If so, then this should scale well. As for directing it, the next question is whether the displaced magma becomes pressurized. That is, if you don't give it enough space to splash by using walls, etc. will it go where there is space? My guess is no, but if it does, then just enclose your space.

The problem with the idea is that it's not easily reloadable. You can't use a construction to get the splash, so you have to repour the piece you are going to collapse. Could be fun to automate, however.

[Da King]

Wouldn't it be possible to achieve a similar effect by placing a steel drawbridge at the bottom of a pit, filling the pit with magma and putting the bridge into an upright position with a lever? You could even attach the bridge to a repeating pressure plate, and have the pit refilled over and over by rapidly pumping in more magma so that magma constantly flies out of the hole. I don't know if the drawbridge flinging is accurate enough though, I guess I'll have to test it. Another idea, why not have a catapult fire stones into the magma? I'm not sure if that one will actually make a splash though. If you wanted to make an easily collapsible roof that can be rebuilt, you could rig up something with water pumps above it to quickly remake blocks of obsidian, and then perhaps drop it in with a bridge below the block.

[alway]

For it to be reusable you would need to do the following (fairly labor intensive) steps:
1: set up a way to cast obsidian blocks above the magma pit
2: mine out the block, leaving only the floor, this is so the obsidian doesn't build up in the magma pool, since walls fill it while floors are destroyed on impact but still make magma jet
3. channel out around the block, making the block fall

However, from my experience magma traps are not used very often, since the enemy usually doesn't run right into where you want them (especially in orc mod where you never want to give a path into your fort due to trapimmune tag).

As far as directing the jet... On further examination, I don't think it is possible. The problem stems from the fact that for the jet to take place, you cave in the ceiling above it, thus making blocking it off impossible.

One experiment which may be interesting to run would be a test of how useful it could be for moving magma up without pumps.

Something like this:

Code: [Select]

WWHWHWW
WWHWHWW
WWHWHWW
WWHWHWW
WMMMMMW
WMMMMMW
WMMMMMW
WWWWWWW
W=wall
H=hatch
m=magmaThis would cause the 4 layers of wall to fall, displacing 3 layers of magma, and the blocks would then pile up underneath making the magma get stuck above them, making the end result:

Code: [Select]

WWHMHWW
WWHMHWW
WWHMHWW
WWHWHWW
WMMWMMW
WMMWMMW
WMMWMMW
WWWWWWWAnd the hatches would let the walls fall without letting the magma fall back down afterwards.

Labor intensive, sure... But a pretty good method for moving small amounts of magma up for forges and the like. By increasing the size of the center walls that fall and displace the magma one could potentially move nearly all the magma in a pipe at the same moment...