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[rhesusmacabre]

The exception is when you want to propel the cart out of magma. Here impulse ramps can't provide the speed to escape, so complicated and unreliable solutions aside, a powered roller is necessary.

What if the cart doesn't STOP in the magma?

Suppose you set it up so that the cart zooms along a few impulse ramps to build up a good head of speed, then dips down into a short magma-filled hallway, then back up onto more impulse ramps? Will that set-up obviate the need for rollers?

I would REALLY like to be able to design an unpowered artillery system.

It's possible with water but not magma, at least not reliably. The problem is that in order for the cart to fill with a liquid it has to be below a certain speed, and this speed is insufficient for the cart to go up a ramp. The best I've managed involves manually pumping magma into a corridor open at one end to allow the minecart clear space to accelerate out, but I doubt it would allow for the constant flow of minecarts needed here.

Has anyone tested stacking carts in a chute? I know that the first two will stack... but will the third one stack on top of the second, or will it Quantum Stockpile on top of the first one?

Further carts join the same space as the second. When the first cart departs, one of the others (presumably the second) drops down to form a new "base", and the cycle continues.

...Just wondering... Loading stuff into bins will only increase the weight of bins, or turn them into explode-on-collision flak shells? I'm not sure, but I think there is no way to knock contents of a bin out of it... Damn, Toady, why didn't you think about it!

Actually the contents of a container (bin of spears, cage of monkeys) can be shotgunned in the same way as a minecart's contents. I.e. you need to have a second wall for the container to hit after the cart hits the first one.

[BastiBasti]

Problem is that with bins, they need to hit a wall but once propelled from a mine-cart their predictability is lost. Maybe for getting a really nice spread on the content fired but magma-dousing has the advantage of being more automatic, therefore ideal for rapid-fire artillery as this thing should be churning out a LOT of carts.

[Girlinhat]

Ultimately you don't really -need- bins anyway.  You can load over a thousand spears into a single cart.

However, for shrapnel bomb effect, it depends on what halts a crate.  If a flying crate hits a minecart, does the crate eject its contents?  If so, your firing range could be littered with track stops set to full friction with carts sitting atop doing nothing.  Fire crates, they arc over the wall, into the firing range, hit the ground, hit a cart, and explode outwards.

Of course, for that matter you could just fire the whole cart as well, and let it skid on the ground and hit the stationary cart...

[gchristopher]

... If a flying crate hits a minecart, does the crate eject its contents?  If so, your firing range could be littered with track stops set to full friction with carts sitting atop doing nothing.  Fire crates, they arc over the wall, into the firing range, hit the ground, hit a cart, and explode outwards.

That's a good question, too. Are full friction track stops good enough? That's a lot of velocity.

Instead of relying on a track stop for that setup, you can put a fortification behind the stationary cart to stop movement, but allow projectiles. I think QuantumMenace was first to post it.

I'm surprised to see all the discussion here on how to load/move carts in water or magma. That's covered pretty thoroughly in the Wave Cannon and Squirt Gun threads that Urist Da Vinci linked to. 

[Girlinhat]

Those use rollers.  We're looking for impulse rail exploits.

[BastiBasti]

Ultimately you don't really -need- bins anyway.  You can load over a thousand spears into a single cart.

However, for shrapnel bomb effect, it depends on what halts a crate.  If a flying crate hits a minecart, does the crate eject its contents?  If so, your firing range could be littered with track stops set to full friction with carts sitting atop doing nothing.  Fire crates, they arc over the wall, into the firing range, hit the ground, hit a cart, and explode outwards.

Of course, for that matter you could just fire the whole cart as well, and let it skid on the ground and hit the stationary cart...

Indeed. Perhaps when explosives and breakable items are added, bins will have the use of being actual shells. Until then simply using a cart suffices.

[BastiBasti]

As Girlinhat said, we're looking to use impulse ramps to fill carts with magma. This will practically be a magma machine gun, and I don't really trust rollers and their power sources reliabilities enough to risk a jam in the artillery, which is amplified as maximum fire rate is essential here. Arguable this could be solved with several lanes, if one fails there are others to fall back on but then there's the problem of creating power for them. Also FPS need to be hoarded when you're rapid-firing fluids at a goblin invasion or FB.

[gchristopher]

Those use rollers.  We're looking for impulse rail exploits.

Ah, okay. The collision-based "rocker" solutions are the only ones I've heard of working.

I'm resigned to the need for power because as soon as you get a good firing rate, the water source needs to be pressurized. If there's any possible flowing water, eventually it will mess up your loading area.

You can work around the need for pumps by building at least one z-level below an aquifer or other good water source and flowing unpressurized water from one z-level above down into the loading channel.

But a fast cannon goes through a lot of water, so you do need to get several aquifer tiles-worth of water teleported into the loading square to keep up with the cannon.

This will practically be a magma machine gun, and I don't really trust rollers and their power sources reliabilities enough to risk a jam in the artillery, which is amplified as maximum fire rate is essential here.

I don't think that concern is well-founded. It's easy to produce 100% reliable power sources and rollers do not introduce any unreliability into a system.

Looking for power-free solutions is totally justified in the pursuit of Science, but I've left super-fast magma machineguns running for years without any glitches. You should consider them reliable using rollers.

Also FPS need to be hoarded when you're rapid-firing fluids at a goblin invasion or FB.

Liquid flow in the target area is by far your most significant FPS concern. Power generation shouldn't be a concern.

[BastiBasti]

I do know power is incredibly reliable, but ultimately it's prone, especially as you need a lot of them without using an aquifer, I was thinking of using the pump into water mill idea which I have found to be able to break, but it may be my stupidity. The suggestion of using an aquifer though seems tempting, but as you said any power will need to be massed up, hence the look for a method using impulse ramps.

[Urist Da Vinci]

So I built a 60-tile-long rail on the surface and several staircase towers to allocate the airspace using about 200 logs. The sky on this special worldgen was raised to 40 tiles high. This length of rail should make the cart reach the maximum speed possible in the game.

First, I shot a minecart about 26 tiles high and 142 tiles away from the point of launch. I had a wood floor made on the ground where the minecart landed.

I then converted the launcher into a shotgun and fired about 25 copper spears at once. The spread was 30 tiles long by 40 tiles wide, falling short of the minecart landing spot (so the shotgun range is 112-142 tiles). The max height reached by the spear cloud ranged from 24 to 28 tiles. If you don't want to shoot things this far, just use fewer impulse ramps in the launcher.

Spoiler (click to show/hide)

I then converted the launcher into a double shotgun and fired some spears plus a cage full of puppies. The puppies appear to have slightly better range than the spears.

Spoiler (click to show/hide)

Launching a dwarf using the single (standard) shotgun seems to break reality, as the dwarf will teleport while in midair between several possible trajectories, as well as continue to take damage from the cart that he left behind. This also means that the dwarf will land from the fall multiple times. I haven't seen anyone survive it. It doesn't happen with the puppies, so I assume it is a bug with riding the cart.

[Kofthefens]

It doesn't happen with the puppies, so I assume it is a bug with riding the cart.

Have you tried launching a caged dwarf as a test?

[Larix]

I experimented with dwarven flight over the last few days, and dwarfs can and will ride flying minecarts over a full embark and come out alive with the proper precautions.

I didn't use impulse ramps but ordinary gravity-fed ramps, and only 28 of them. Since i had a ridiculously huge mountain to start from, that still placed the launch ramp sufficiently high up that a dwarfless cart struck the far end of the (4x4) embark area two z-levels above ground (~160 tiles horizontal flight).

Going by information on this and other threads, i built a rail of track at the maximum height the cart reached and placed there a series of switchable track stops and another launch ramp. With the track stops turned off, the ramp will send the cart into another jump, gaining another 7 (on top of the 14 so far) z-levels, for the price of a significant speed loss.

The launch ramps all used the advertised design:
  /
_/W
Wall-backed ramp, and another bit of ramp on top of the wall. Catching the flying dwarf-ridden cart at the apex of its trajectory and stopping it via track stops allowed for a perfectly safe flight - no combat reports, no wounds on seven or eight flights. Catching a descending cart with a flat track or a one-tile ramp leading into flat track caused the dwarf to take collision damage from the cart, once. I've not seen any serious wounds yet, but that was probably just luck - no headstrikes so far. Five test flights caused bruised organs twice, bruised muscle (arm/leg) twice and a broken hand. The severity of the hit taken appears independent of the drop distance - falling four z-levels and falling 87 (!) didn't appear to make a difference - but cart weight is likely a factor; i used wooden carts on both test routes. Still, i got living dwarfs delivered completely unharmed over 40 tiles horizontally and 14z up, and slightly bruised over ~140 tiles horizontally and a net of 65z down.

It seems that launching dwarfs into battle riding minecarts is a risky proposition - even with armour on, letting them descend onto a track stop is likely to injure 10-20% of the force sufficiently that they won't enter combat. And that's ignoring the logistics (getting several dwarfs to launch in a timely fashion) and the necessity to activate them _after_ arrival, since push vehicle can only be done by civilians.

The uniform collision damage also suggests that a falling minecart could be used to move a dwarf down over huge distances very quickly and at only moderate risk to their life and limb.

[Suoli]

I then converted the launcher into a shotgun and fired about 25 copper spears at once. The spread was 30 tiles long by 40 tiles wide, falling short of the minecart landing spot (so the shotgun range is 112-142 tiles).

Have you tried a barrel, starting after the fortifications, to influence or restrict the spread? If that works, the next step would be to build the barrel out of bridges or doors for a semi-aimable cannon.

[MattStriker]

I then converted the launcher into a double shotgun and fired some spears plus a cage full of puppies. The puppies appear to have slightly better range than the spears.

That's another one of those 'only in Dwarf Fortress' quotes.

[Urist Da Vinci]

I then converted the launcher into a shotgun and fired about 25 copper spears at once. The spread was 30 tiles long by 40 tiles wide, falling short of the minecart landing spot (so the shotgun range is 112-142 tiles).

Have you tried a barrel, starting after the fortifications, to influence or restrict the spread? If that works, the next step would be to build the barrel out of bridges or doors for a semi-aimable cannon.

That would only restrict the spread. However, what people need to try is to put powered rollers near the end of the track, oriented perpendicular to the direction of cart motion. That might give the cart and contents some sideways drift.