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[QuantumMenace]

Combat physics treats Water [833] as a giant rock weighing 459, IIRC, heavier than most boulders. So, what if you use it in a "minecart shotgun" setup? Each cart only fires one glob at a time, but they don't need to be refilled manually, so you can have it repeat very fast, with unlimited ammo so long as you have a water source.

This was designed before I discovered the physics exploits detailed on this thread, so it doesn't take advantage of them yet, and this is only one half of my initial plan. It was intended to have 8 lanes/barrels, with the other 4 in a mirror image of the ones shown.

Spoiler (click to show/hide)

Floor -1:


The entrance corridor. The entrance and exit are ramps up against fortifications. Units can use the ramps, but the fortifications don't block the water globs, and units can get smacked through the fortifications as well.

Notice the stationary minecarts behind the fortifications at right. A minecart will fly through a fortification if it's over a gap, but it can't fly through another immobilized minecart. They run down the ramp, hit that cart and fall into the gap. There's an extra fortification width on each side, so water doesn't hit the walls behind the fortifications.

Hatches block the outlet from the magazine below until ready. A floodgate can be closed to block one lane, since four lanes fill the corridor with enough water to block pathing even with the drainage system described below.

Floor -2:


The water-filled "magazine" and perpetual motion aquifer "reactor". The carts are all copper, and unlike wooden carts, aren't likely to be pushed around by moving water. The pumps transmit power to the rollers that fill the magazine. Each lane has the roller on "low" speed, except for the 2 tiles farthest to the right, which has "highest" speed to keep it clear for carts falling through the holes above. Rollers may not transmit power lengthwise but always transmit power to their sides, so as long as their lengths are staggered you need no additional gearboxes.

The holes for pumping from the aquifer were widened somewhat on the aquifer level to bring in more water flow. Most of the carts look yellow because of mud piles.

All the other rollers for pushing carts east up the ramps are highest speed.

Ground Floor (0)


Entrance and exit of the corridor shown, with part of the ramp upwards visible as well. The drainage system consists of pumps above the corridor pumping through grates and draining back to the aquifer. The set on the right pulls water from 2 tiles to the left of the fortifications, so anything the fluid pushes stops before being pushed into the fortifications.

Floor 7:


Top floor of the ramp, where carts turn around and speed back down the ramp.

In action:

Each lane fires a glob every 15-20 ticks, though with only 20 carts there's a periodic gap in firing. The water is very good at blowing goblins away from the inner ramp, and may trap them at the far end while it hammers them to death. I haven't been able to test its effectiveness on larger creatures, though, and if you want to make sure it finishes them, seal off the opening with a retracting bridge.

Of course, there's many variations you can use this with, such as:

-use ‼magma‼, obviously. Though since it blocks pathing, you might want to use a floor made of downward stairs with drainage underneath. Remember that collisions can make creatures fall through, and that down stairs block wagons.
-fire it across a narrow bridge, or down the length of a winding bridge. Underneath have a drowning chamber or whatever hazard you like.
-Fire it outside in freezing weather, preferably at least 1 level above ground. Remember to keep the water-filling and cart magazine sections underground to prevent them freezing, and shower the invaders with deadly freezing rain.

I hope to have an enhanced version using derail physics eventually. Enjoy!

[Loud Whispers]

That's no watergun, that's a science cannon!

[Scruffy]

Interesting! Keep us posted!

That's no watergun, that's a science cannon!

The greatest quoteI have read.

[backora900]

Nice work and I admire your engineering skill.
I feel almost sorry for anyone who want to attack your fortress (even amphibious creatures ).
One note: forbid minecarts

Now I have 3 questions:
- I tried constructing this liquid-minecart "magazine" myself but somehow I was loosing minecarts right at the beginning of it. Because after few laps the minecart went too fast and ended "in ground". Did you have the same problem with this setting?

- Does it matter in which direction does a minecart falls on those rollers on floor -2 (right after it "fire")? For example when "shotgun" is firing E->W but rollers are going N->S.

- Could you lace water in that magasine with gnomeblight? Or GCS poison? Or some other fun-liquid?

[Bobnova]

Holy hell that's beautiful. I must build this.

[DrKillPatient]

Perhaps it's worth researching the creation of the shortest firing system possible. Ideally, you'd have a cart striking the wall and firing water (or other items) consistently on every tick while the device is turned on, using as few carts as possible. Does this design recycle carts automatically, or do they need to be replaced by dwarves once they go through the barrel? I'm fairly certain that a fully-automated, no-dwarf-interaction-needed water cannon is possible...

[QuantumMenace]

One note: forbid minecarts

Absolutely, forgot to mention that.

- I tried constructing this liquid-minecart "magazine" myself but somehow I was loosing minecarts right at the beginning of it. Because after few laps the minecart went too fast and ended "in ground". Did you have the same problem with this setting?

I don't know what you mean by "in ground". Did the rollers push a train of them through a wall? I did have some problems using a magazine with higher roller speed, where they would release too fast and run into each other where they're supposed to fire. If you're using wooden carts the water can push them out of alignment too.

- Does it matter in which direction does a minecart falls on those rollers on floor -2 (right after it "fire")? For example when "shotgun" is firing E->W but rollers are going N->S.

Probably not if you only have one lane, but otherwise that will cause multiple lanes to be taken up by the same track unless they're staggered diagonally, and possibly make carts in other lanes unable to fall soon enough to keep the next cart from hitting them.

- Could you lace water in that magasine with gnomeblight? Or GCS poison? Or some other fun-liquid?

I honestly don't know. I think it's called "water laced with water" because it impacts the goblin on a tile where's there's water already. Does anyone know if contaminants get transferred into minecart water?

Perhaps it's worth researching the creation of the shortest firing system possible. Ideally, you'd have a cart striking the wall and firing water (or other items) consistently on every tick while the device is turned on, using as few carts as possible. Does this design recycle carts automatically, or do they need to be replaced by dwarves once they go through the barrel? I'm fairly certain that a fully-automated, no-dwarf-interaction-needed water cannon is possible...

You can build a shorter accelerator using the exploit described here. The speed depends on the length, and the launch range appears to depend on speed. You can't release carts too closely together or they'll hit each other before they fall in the gap.

This design does automatically reuse the carts, which is why I call it fully automatic. Carts move west out of the magazine, back east up the ramp, west down the ramp, fire, fall into the gap, then are pushed west where they fall back into the magazine.

[DrKillPatient]

- Could you lace water in that magasine with gnomeblight? Or GCS poison? Or some other fun-liquid?

I honestly don't know. I think it's called "water laced with water" because it impacts the goblin on a tile where's there's water already. Does anyone know if contaminants get transferred into minecart water?

Perhaps it's because the water glob is collected in the cart while still immersed in water, so the glob gets a water covering. I'm not sure of the exact point at which that occurs. On the other hand, I had a glob of magma strike a yak, and on the first strike, it was called "magma laced with yak's blood". The names might be calculated after the first impact, which might splatter the glob with the blood of the creature that it hits. If that's true, maybe the creature gets covered with water as the glob strikes them, then the glob picks up that covering from the creature, thus becoming laced with itself.

As for contaminants in minecart water, I don't know. Try to throw multiple hostile animals into the cistern so that they fight in there and contaminate it, then see if the minecarts carry "water laced with blood".

[Urist Da Vinci]

I'm imagining a system where carts drive through a device that automatically refills them, and then loop around to fire, and then loop back to the refilling station. With the trackramp physics exploit, we could possibly make compact autoguns that don't require magazines. Then, you just need to see how many carts can be squeezed into the loop to reduce the ticks between shots.

The ultimate goal, of course, would be a "magma particle beam" weapon.

[Urist McSpike]

In the words of the Guinness guys.... "Brilliant!".

As for clearing the water...  My favorite method, in my drowning trap hallways, is to use 3 levels.  The floor of the drowner is entirely lined with retracting bridges.  The level below is channeled out, and is floored (mostly) with grates.  The level below that has sufficient drainage area to spread out all of the water from above.  When I'm done drowning the smelly invaders the goblins are done frolicking in the water, I open the bridges, which drops everything below, close the bridges, and start looting the bodies storing the goblin donations almost immediately.  I'm sure that kind of floor could be used in your setup, and is a whole lot faster than pumps.  Plus you have a secure area for your dwarves to recover the goods, instead of having to go out where they can be attacked.

[lcy03406]

For path issue, do not shot magma. Dig a magma channel in the west to welcome goblins laced with water, resulting iron junks and steam. I don't know if the iron junks will fall INTO minecarts or if it's better to use dragon instead of magma..

[Wrex]

You CAN always use water laced with extract, for the extra kick.

[zuglar]

- Could you lace water in that magasine with gnomeblight? Or GCS poison? Or some other fun-liquid?

I honestly don't know. I think it's called "water laced with water" because it impacts the goblin on a tile where's there's water already. Does anyone know if contaminants get transferred into minecart water?

Perhaps it's because the water glob is collected in the cart while still immersed in water, so the glob gets a water covering. I'm not sure of the exact point at which that occurs. On the other hand, I had a glob of magma strike a yak, and on the first strike, it was called "magma laced with yak's blood". The names might be calculated after the first impact, which might splatter the glob with the blood of the creature that it hits. If that's true, maybe the creature gets covered with water as the glob strikes them, then the glob picks up that covering from the creature, thus becoming laced with itself.

As for contaminants in minecart water, I don't know. Try to throw multiple hostile animals into the cistern so that they fight in there and contaminate it, then see if the minecarts carry "water laced with blood".

When experimenting with water-filled minecarts a while back, I accidentally flooded my booze stockpile. All the minecarts were filled with "water laced with dwarven ale [833]" after that. I think if you wanted to do it on purpose you'd just need to have somebody dump the liquid of choice in the water you fill the minecarts with?

[zuglar]

In the words of the Guinness guys.... "Brilliant!".

As for clearing the water...  My favorite method, in my drowning trap hallways, is to use 3 levels.  The floor of the drowner is entirely lined with retracting bridges.  The level below is channeled out, and is floored (mostly) with grates.  The level below that has sufficient drainage area to spread out all of the water from above.  When I'm done drowning the smelly invaders the goblins are done frolicking in the water, I open the bridges, which drops everything below, close the bridges, and start looting the bodies storing the goblin donations almost immediately.  I'm sure that kind of floor could be used in your setup, and is a whole lot faster than pumps.  Plus you have a secure area for your dwarves to recover the goods, instead of having to go out where they can be attacked.

Don't building destroyers target floor grates from above? And what do you do with amphibious mounts like giant toads?

[lcy03406]

When experimenting with water-filled minecarts a while back, I accidentally flooded my booze stockpile. All the minecarts were filled with "water laced with dwarven ale [833]" after that. I think if you wanted to do it on purpose you'd just need to have somebody dump the liquid of choice in the water you fill the minecarts with?

So that's quite easy, buy a barrel of GCS venom from dwarven caravan and dump it into the magazine?Will it work?