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[Girlinhat]

So, I want to weaponize some water.  I made a test fort, made a huge cistern, and opened the dual floodgates.  A torrent rushed out, I was pleased.

I set a lever in front of the floodgates and a wall behind it, and opened them.  The namely Science rat who was pulling the lever almost drowned, but wasn't heavily effected.

I moved the lever and wall back a bit, and this time the peasant was pushed around some after the initial surge, but not smashed like I wanted.

I want to let out so much water that it slams things against walls and kills them.  How have I failed this?

[Naryar]

Can water push things hard enough to slam into a wall and kill them ?

[Girlinhat]

I've heard it can, which is the basis of the rarely-used "pressure washer" trap design.

[Naryar]

Honestly I would just combine flusher with pit trap. Possibly with upright spikes or weapon traps at the bottom if you have the metal.

[Sphalerite]

I've built pressure-washer traps.  I've never seen the force of the water itself do any damage or push invaders against a wall hard enough to damage them.  I don't think water pressure can do that.  What it can do is push invaders off a ledge and down a 12 Z-level pit, which will smash them.

[Hyndis]

I've built pressure-washer traps.  I've never seen the force of the water itself do any damage or push invaders against a wall hard enough to damage them.  I don't think water pressure can do that.  What it can do is push invaders off a ledge and down a 12 Z-level pit, which will smash them.

This.

Its highly effective as well. Just make sure you have some sort of drainage system in the pit so that you can reclaim the valuable goblinite.

[Girlinhat]

Hmm, alright then.  Although with the pit, it should stun then from the fall, and then drown them if they're not already dead.

Also of note, in my experimenting I found a way to rapidly increase your flow.  Pumps pressurize water, every time the "pumping" action is performed, water is shunted out.  Utilizing this, you can very easily get 4 pumps, each facing inward to a single tile, and have 4 pumps pushing water down, much faster than pressure alone.  Combined over multiple levels, 4 per level, you can get some pretty instant floods going.  The only thing to watch out for, is placing walls on the corners so that the water chute is normally very dry, and the pump flow isn't weakened by corner leaks.

This theory applies to magma as well, because pumps pressurize magma, you can get some nasty U-bends generated.

[Quietust]

If you have any uncertainty as to how water works in Dwarf Fortress, read the Hydrodynamics Education post and be enlightened.

[Hyndis]

If the pit is deep enough the fall will kill them. Its not the water that does the killing, its the pit. The water just pushes them off the ledge so they fall into the pit.

Alternatively you don't even need to use water at all. Just use retracting bridges over a narrow ledge. The bridges don't harm anything, but they do fling things around randomly. Since there is a narrow ledge over a deep pit the random flinging will mean that goblins end up falling into the pit.

You can make the pit as shallow or as deep as you want, and put whatever you want at the bottom of the pit.

[denito]

Also of note, in my experimenting I found a way to rapidly increase your flow.  Pumps pressurize water, every time the "pumping" action is performed, water is shunted out.  Utilizing this, you can very easily get 4 pumps, each facing inward to a single tile, and have 4 pumps pushing water down, much faster than pressure alone.  Combined over multiple levels, 4 per level, you can get some pretty instant floods going.  The only thing to watch out for, is placing walls on the corners so that the water chute is normally very dry, and the pump flow isn't weakened by corner leaks.

This theory applies to magma as well, because pumps pressurize magma, you can get some nasty U-bends generated.

Well now that's interesting...  And you could efficiently connect the 4 pumps to a power source by constructing a gear assembly in the hole in the middle so it touches all 4 pumps (it won't affect the water flow).

Edit:  I fail at reading - you already said this.  I wonder if you built a tower that stacks these things on multiple Z-levels, would it force water through that much faster, or does it only work if the pumps are on the same Z level?

I might test this by building two cisterns filled by U-bends, and see whether a tower on different levels or two 4-pump crosses on the same Z-level fills any  faster than a single cross.

I like you invention Girlinhat because I've wanted to build a network of underground magma pipes and holes that could deliver a targeted blast of magma to any point on the map based on levers that move bridges and floodgates.  The basic idea is that you divide the map into a grid, and you have a set of levers for rows, and a set for columns.  Then you pull the lever for the row and column you want to send magma to and it opens up floodgates or hatches on that row and column.

Something like this:

Code: [Select]

2 Z-levels below ground (3 floodgates and tunnels)
(the %% pump is for illustrative purposes only; the real pump would be at a higher Z level)

 %%--+-+-+
     X X X
     | | |
     | | |
     | | |


1 Z-level below ground (hatches)

     H-H-H
     H-H-H
     H-H-H

Ground level (holes)
     _ _ _
     _ _ _
     _ _ _


Of course on the real map it'd be much more spread out.

The dashes between the hatches do no represent tunnels but rather that a row of hatches is all connected to one lever.  The drawback is that although an MxN grid only requires M+N levers and N floodgates, it needs M*N hatches.  It seems like there ought to be a way to do it with only M devices for the rows, but I couldn't figure out how.  I would guess it might involve using a bridge to cover or unblock a row of tunnels, but I don't see how you would prevent the magma from going over the bridge to get to the wrong row.

Another way to do it, that just struck me, is to instead of using a grid, have a binary tree of tunnels, where at each point the magma can go left, or right (accomplished with a floodgate and raising bridge connected to the same lever so one is always up and the other is always down).  Then you'd send magma to a certain hole by programming its binary "address" into the levers.  However, although it would only require log-base-2 levers, it would require even more hatches and floodgates.

[wuphonsreach]

Alternatively you don't even need to use water at all. Just use retracting bridges over a narrow ledge. The bridges don't harm anything, but they do fling things around randomly. Since there is a narrow ledge over a deep pit the random flinging will mean that goblins end up falling into the pit.

Advantage of a water-flush system is that it can be used on titans / FBs / larger critters where a bridge won't work.

[Hyndis]

Alternatively you don't even need to use water at all. Just use retracting bridges over a narrow ledge. The bridges don't harm anything, but they do fling things around randomly. Since there is a narrow ledge over a deep pit the random flinging will mean that goblins end up falling into the pit.

Advantage of a water-flush system is that it can be used on titans / FBs / larger critters where a bridge won't work.

This is true, but creatures too big for a bridge to work normally only come one at a time. If you have your barracks right after the bridge with a lot of on duty soldiers there then they should be able to easily dispatch the creature just by sheer numbers.

Goblins are only dangerous because they come in large numbers. A bridge that flings them to their doom eliminates the advantage they have in numbers.

[Alastar]

I used to experiment a lot with such designs because I find the concept technically sweet (a grand unified plumbing system, to turn decorative waterfalls/showers/water sources into either drowning traps or flushing systems at the pull of a lever).

The basic pipe arrangement was something like this:

###########
++
# #########
###


Unfortunately, water pressure is modeled only with regards to how the water itself moves - it doesn't push things at all and we have to rely on depth gradients to do that. I hoped to make this work by setting the lever to the right door (toggling normal flow or pressure) on repeat. It didn't work too well - water behaviour was less predictable than expected and depended heavily on local layout, and things got stuck after being pushed a few tiles.

[Itnetlolor]

A good setup is having an artificial bridge made up of up/down staircases or down staircases over a deep opening, and drop water from above when intruders start coming in. It should push them through the starways making them fall, and also mistify the water so collecting won't require draining the pool at the bottom of the drop pit.