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[taptap]

I have a good trap to offer. Maybe I can do proper !!science!! after all?

1. Magma trench, no ramps at z-2
2. Minecart circuit, with some speed regulation both against too high speeds, i.e. cart jumps over the whole trench, and too low speeds, i.e. minecart falls into trench, z-1
3. Invader path at z+0 (next to the magma trench, so I did in the prototype)

When activated the minecart circulates, bouncing off the magma a few times per round, producing steady magma mist each time it bounces.

This trap design is certified as energy class A+, since no (?) magma is wasted. (It certainly works with the amount of magma, my slow minecart magma lift can handle.)

I have a working prototype, but the speed regulation is still somewhat whacky.

Spoiler (click to show/hide)

Image of z-1. (Used dfhack map reveal to find enough material for my colour coding needs.)

Edit: While this works with a holding area, where enemies are exposed for a while, it is likely not working that great for 3 wide bridges or so, like magma mist traps with submerged minecarts bouncing around.

[NJW2000]

I am totally inexperienced with large traps, but have a volcano, and a river, and have often wondered if something like this might work

M=magma
W=Water
 =miner
O=hollow/obsidian

          M
    O
          W

 These would be stacked, in a huge column, with a legendary miner on each one. Can I get miners to automine the obsidian, and would this setup even create obsidian? Would depths be important as well?

The intended effect is a column which rapidly fills with stones, which may fall zlvls till they impact many floors below.

Would most of the stone likely be obsidianized? And would the water drown the miners? Would I have to control depth by alternating the design floors with other floors? And would the supply of rocks be fast enough with, say, 8 legendary miners, to have much impact?

[NW_Kohaku]

I am totally inexperienced with large traps, but have a volcano, and a river, and have often wondered if something like this might work

M=magma
W=Water
 =miner
O=hollow/obsidian

          M
    O
          W

 These would be stacked, in a huge column, with a legendary miner on each one. Can I get miners to automine the obsidian, and would this setup even create obsidian? Would depths be important as well?

The intended effect is a column which rapidly fills with stones, which may fall zlvls till they impact many floors below.

Would most of the stone likely be obsidianized? And would the water drown the miners? Would I have to control depth by alternating the design floors with other floors? And would the supply of rocks be fast enough with, say, 8 legendary miners, to have much impact?

I haven't done them myself, but generally, you want to work with pumps, not miners, and it works better if you put the two fluids above one another, not on the same floor.  The lower one may be best to work with floodgates next to bridges (probably the water) and the one above can be pumps (for slower magma).  That should create a cave-in machine.

If you have them both on the same floor, letting water and magma leak into a tile on the same level, you have the problem of obsidian being created right on top of the exit.  If you have a dwarf right on that diagonal, then the fluids will travel the diagonal to hit your dwarf, which causes obisidianizing of your dwarf.  If you're channeling the diagonal, I'm pretty sure the dwarf pulls the boulder back with them. 

[NJW2000]

Wait, so how would a cave-in machine look? Would the bridges be removed/lifted to let the magma fall?

[NW_Kohaku]

Wait, so how would a cave-in machine look? Would the bridges be removed/lifted to let the magma fall?

Bridges do not provide support, which is why you'd use them to funnel water, as any wall touching nothing but bridges will instantly cave-in.

[NJW2000]

So the setup

     B
   BOB
     B

with what beneath the obsidian?

[NW_Kohaku]

I would make it like the following:

Code: [Select]

Side View:
  ░≈≈░
  +RR+
░~~  ~~░
++D  D++

░ = Wall
+ = Floor
~ = Water
≈ = Magma
R = Retracting bridge
D = Drawbridge

For the purpose of reading this, floors take up every other row.   

The drawbridges can be lifted towards their sides to shut off water flow, and the (magma-proof!) retracting bridges can be shut to turn off the device.  When bridges are down and hatches are open, water pours into the gap in the bottom middle, as does magma. 

This form of design would require pump stacks. 

In practice, it should be capable of easily raining "orbital strikes" of obsidian down on a path that is 2 tiles wide by however big a trough you can reliably pump full long.  Hypothetically, it should be capable of obsidian-casting a slab that slams the whole killzone in a single strike. 

You will almost certainly need to re-carve the killzone upon use, although you might be able to set up optional ramps, where, as each successive floor is hit with a cave-in, it creates a new floor for a new path to the fortress that can be pathed across.  Remember, cave-ins obliterate constructed floors or things like bridges, so building a floor or bridge through the excavated obsidian allows you to easily set up multiple floors that are struck at once.

In practice, this thing is utter overkill for goblins. 

[NJW2000]

Sooo... the retracting bridge keep the magma from falling onto the target, while the drawbridges surround the whole thing?

How would this work against demons?

[NW_Kohaku]

Sooo... the retracting bridge keep the magma from falling onto the target, while the drawbridges surround the whole thing?

How would this work against demons?

The drawbridges keep the water from flowing until you let them down.  This whole contraption should be at least 2 or 3 z-levels above the killzone.  (Feel free to put it wherever your highest z-levels are to create zombie raven squishers.)  Also, hypothetically, if you build several of these, and have a positively obscene amount of water and magma being pumped, you could set up several of these in a row, dropping obsidian on 2/5 tiles on the map, barring the column for the water and magma. 

And it works brutally effectively against demons.  In fact, it's basically just a non-checkerboard layout of Aussieguy's famous checkerboard.  If you're dropping obsidian from above, I recommend flooring over the killzone so they don't fly out, however.  The obsidian will crash through built floors.

[NJW2000]

Right, so a know design, then? So it works?

I could probably set this on repeat, right, with dwarve? Or would a repeater be better?

[Oaktree]

My current fort in 34.11 called Geniushammers has been playing with accelerator coils.  A number of prototype devices have been built around these since they are compact, easy to build, and have a variety of uses.  I also like their quick reaction time to a lever being pulled to open the door - the cart is ready to roll!  Downside is that a coil can only hold one cart at a time, so barring a return system it's a one-shot deal.

First use has been as a basic building destroyer trap.  Heavy (gold or platinum) minecart in a coil and wait for the door to be attacked. (Optionally just hook the door to a pressure pad a two spaces away where the destroyers prefer to stand.)  Cart fires out and you get something's attention at the very least.  Large creatures can take the hit, and I've only bruised or stunned forgotten beasts with one so far.

I have also put a coil's door on a lever and fired it down an open space into an oncoming goblin unit during sieges.  Results are mixed since I have seen the cart only hit and hurt 1-2 creatures.  But I've also seen it pinball 4-5 creatures into each other and also directly hit a Goblin Elite Archer in the head.   

Second use has been as a light anti-intruder trap as part of some in-depth defenses.  An wide open area has a coil at the north end which will fire the cart south - where a curve turns the cart around to send back into a coil.  About 10-16 tiles from north-to-south.  A few of these set-ups are augmented with additional accelerators at the south end to help return the cart to speed after collisions.  Essentially a "frogger" device using a coil to hold the cart at speed until deployment.  Deployed between caravans or just after the ambassadors and liaisons get into the fortress, and during sieges.

Results during sieges have been mixed since hitting a heavy mount like a cave croc can slow or stop the cart on level ground.  Have also seen one tear up most of a goblin cavalry squad by itself.  The device is stellar against kobolds, snatchers, and ambush squads - you just suddenly see body parts and corpses appear in the back end as they get exploded by the collision effects.  However, this device will eat caravan guards and wayward fortress residents.  I have an extra door on a lever to cover the return side - it's the "safety" to totally seal the coil from access, or can be used to stop the cart entirely if necessary.

Lastly, I have a working watergun which uses a coil as part of the main firing mechanism.  It's a standard design with a cart hitting a wall, firing the ball through a fortification on the level above, and then dropping down a hole into a reservoir to be re-filled and then cycled back to the accelerator level to be fired again.

The coil can hold a water-loaded cart which will then fire the initial water ball 3-4 ticks after the lever is pulled.  Cyclic fire rate after that point with a single cart is roughly 92-95 ticks after that point.  I have also experimentally had a second cart dropped into the system and which initially fires about 35 ticks after activation.  This will double the rate of fire, but I have also seen "cart creep" with a cart eventually catching up to and colliding with the other cart to cause a jam.  [Diagrams below]

Water ball trajectories and velocity seem to be variable.  On a range that is 30 tiles long and 5 tiles wide wall impacts occur anywhere from 6-7 tiles down range to balls hitting the end of the range with no side deviation.  (Experimentation in a freezing biome with a water gun has indicated that trying to "ice" targets is a uncommon occurrence and is more like to result in ice walls blocking the field of fire.)

The gun itself is pretty straightforward.  As is dumping the cart into a trench of water that has a reservoir the next level up to keep the trench filled to 7/7 water.  (I fill the reservoir from the fort's aquifer, and also installed drains, etc. so that maintenance can be done.)

The tricky and frustrating part has been getting the ramp and track combinations right that will lift a loaded cart out of the trench, out of the reservoir, and then additionally back up a few levels to feed it back into the accelerators.  That is the main thing I want to get a diagram or picture out of in order to save others the trial-and-error effort if they want to build one of these.

==== Design pictures forthcoming====

[Chaine Maile]

This may inspire me to get back into designing my flaming lignite Boulder cannon. I've been away for a while, but still toying with super weapon ideas myself.

I've also always liked to build in some sort of emergency lockdown. For example a large pillar of natural rock suspended over a spiral stair. Pull lever, and something like a magma piston crashes down. This seals all the levels and wings from each other. From there survivors can find emergency picks to dig their way out of quarantine.

[NW_Kohaku]

First use has been as a basic building destroyer trap. [...] Large creatures can take the hit, and I've only bruised or stunned forgotten beasts with one so far.

If you want to have a more punch, you should use a setup like Larix has earlier in this thread, where water is stored in a tile above a locked door.  When the building destroyer smashes the door, the water drops, and it falls on a pressure plate, triggering the trap.  Use a second door just behind the first to keep the FB in position. 

The main problem with nothing but a cart on a ramp behind a door is that they have no chance to really accelerate, which means the really heavy creatures don't take much damage.  Making the water-activated pressure plate open a door or hatch holding a cart back, and let it have some room to accelerate, however, and you have a far more deadly cart. 

RocheLimit's post, however, has a great setup for a FB trap, however.  It could possibly use some more manually-intensive expansion, though.  Once trapped, you might set it up for target practice with a sufficiently potent melee force or marksdwarf training if it is not terribly dangerous, or you might set it up for obsidian casting if it is.  (RocheLimit already has a method of getting water into that cell, just add a path for magma, and you can obsidian cast every FB that walks into the trap!)

[Sanctume]

I am wondering, can burning lignite (block or furniture) combined with a drop of magma starts burning the item to create smoke that can incapacitate or kill creatures in an small enclosed tunnel/room?

z+1: Let's say I have a magma pipe with flow controlled by a magma safe floodgate or raising bridge.
z+0: The level of the close-able  room/tunnel where the invaders path through, and split/separated by a fortification where the smoke can pass through.
z-1: A passage access from inside the fortification to place lignite item below where the magma can drop from z+1.

So it's chemical warfare if smoke can harm invaders.  When invaders path through the z+0 hallway, they are trapped via raising bridges. 
While they are trapped in that enclosed space, release a tile of magma from the z+1 to drop on the lignite items down in z-1.
I am assuming that a burning lignite will produce smoke, and this smoke will travel up at up to least z+0 level and pass through the fortification and suffocate those in the enclosed hall.

Will something like this work?

[NW_Kohaku]

I am wondering, can burning lignite (block or furniture) combined with a drop of magma starts burning the item to create smoke that can incapacitate or kill creatures in an small enclosed tunnel/room?

z+1: Let's say I have a magma pipe with flow controlled by a magma safe floodgate or raising bridge.
z+0: The level of the close-able  room/tunnel where the invaders path through, and split/separated by a fortification where the smoke can pass through.
z-1: A passage access from inside the fortification to place lignite item below where the magma can drop from z+1.

So it's chemical warfare if smoke can harm invaders.  When invaders path through the z+0 hallway, they are trapped via raising bridges. 
While they are trapped in that enclosed space, release a tile of magma from the z+1 to drop on the lignite items down in z-1.
I am assuming that a burning lignite will produce smoke, and this smoke will travel up at up to least z+0 level and pass through the fortification and suffocate those in the enclosed hall.

Will something like this work?

Just put the burning lignite in a 1-tile wide hallway, and make the invaders path through the lignite tile so that they catch fire.  Seems easier. 

Just make sure the path is winding enough that they burn to death before reaching your booze piles.