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Plan A

2 (15.4%)

Plan B 1.0

2 (15.4%)

Plan B 2.0

9 (69.2%)

Total Members Voted: 13

[Tacomagic]

Unfortunately, according to the wiki, stuff does not fall into a minecart when dropped from above. I wish it worked, there's just so many wonderful uses for that kind of mechanic... Like a quantum stockpile inside a minecart, capable of unleashing a whole mountain's worth of stone on impact

Kinda what I thought.  It's why you can't drop a minecart into a minecart.

[flameaway]

Have you tried firing lignite through a magma mister?

Failing that you could try to set up 1 tile thick magma fall and fire the boulder through the stream.

[flameaway]

Code: [Select]

.
%
%
#

z1

# = grate
%
% = pump
. = floor
H = channeled hole
On z1 the magma pump draws from the hole channeled under the grate

Code: [Select]

H
%
%
H

z2

z2 pumps from the north

Put a mine cart on the grate and load this mini pump stack with recycling magma.  The cart will load with (2) magma.  I doubt that lignite already in the cart will ignite.  But I wonder if it might when the cart unloads?

This pump setup makes a very good and fast cart loader (most especially if you create a quantum mine cart stack by pushing a cart onto the bottom cart from the top channel, but that is a whole 'nother story).  You can also try and fire through the stream.  I'd set up a bunch of these magma misters in a row and then fire through them to increase  the odds that magma and lignite are in the same tile at the same time. 

I doubt it will work though, because I think the lignite and magma have to be at rest for the lignite to combust. 

Note:

The only three ways I know to get stuff in mine cart
1) Surround it with fluid to a depth of at least 6/7 in which case the cart will load with 2 units of that fluid. 
2) Put two or more carts in a quantum stack and run a fluid past them using the pump setup above.  In which case the bottom cart takes 2 unit of fluid from the stream and loads two units as you'd expect.  The upper carts takes one unit of fluid and load the carts with two, thus creating fluid from nothing. Makes a nice loader for a magma or water cannon. (haven't tested this with stacks greater than two mine carts)

3) Have a dwarf put stuff in the cart. 

[Quietust]

Lignite won't get set on fire by magma unless it's sitting in the magma long enough to heat up to its ignition point, and that's going to take a while.

Temperature transfer in DF is fairly simple - most temperature values have a whole part (in "degrees Urist") and a fraction part (which ranges from 0 to the material's SPEC_HEAT minus 1). Once per tick, the game calculates the relevant temperature difference (e.g. between the item itself and the tile in which it is located) and adds that to the fraction part, then adjusts the whole part until the fraction part is within range. For example, a piece of Lignite (which has SPEC_HEAT 409) at temperature 10015.0 (room temperature underground) exposed to Magma (temperature 12000) will heat up by 1985 fraction units, which will increase its temperature to 10019.349. In order to reach its ignition point of 11440, it would need to be in the magma for a total of 517 ticks, over 5 seconds at 100fps.

If you want to heat it up faster than that, you'll need to use dragonfire, which has its own issues.

[Button]

I fiddled with this kind of stuff in .34.11 and found that the requirement for picking up magma/water was not time spent but rather movement speed - carts moving at up to 40 000 (high-speed roller) would reliably pick up water, those moving at 50 000 or more (highest-speed roller) wouldn't. Problem with magma is that at 40 000 speed, friction in magma will stop a cart on a single tile, so you need a trickier construction to make it work.

Btw Chaine Maile, I use a bridge-drop system to load my magma. 1x1x2 magma chamber with a bridge at the bottom. Minecart triggers a pressure plate as it rolls in; minecart comes to a stop and fills; pressure plate fires (100-tick delay for bridges); minecart and magma fall onto sloped track; magma continues flowing out fortifications while minecart picks up speed from impulse ramps below.

In order to reach its ignition point of 11440, it would need to be in the magma for a total of 517 ticks, over 5 seconds at 100fps.

If you want to make sure it stays in the magma for at least 517 ticks, you can use the bridge-drop magma loader and connect the pressure plate to a delay circuit instead of directly to the bridge.

Or, since you want this to be a triggered weapon anyway, you could just leave the minecart with its flaming ammo in the magma until needed, and only then pull the lever. I believe a boulder of lignite will remain burning for something like a year before it expires.

[Chaine Maile]

517 ticks of magma exposure was not what I observed in the "drop magma on a minecart" experiment. I placed a minecart filled with combustible fuel (half coke bars, half charcoal bars, and one wooden bin) inside a 3x3 circle of walls and a single fortification. Outside the fortification I placed a deep pit for the magma to flow into and evaporate on a lower Z level.

My first attempt I dropped 1/7 unit of magma. I watched it evaporate without ignition of minecart contents. Second try I dropped 7/7. On that try the tick by tick showed combustion. The wooden bin vanished long before the magma reduced down to 5/7 units. This caused the minecart to fill the empty space the bin had taken with magma.

I am not seeing 517 ticks delay from 7/7 magma exposure to coke and charcoal bars. *shrugs*

I'm redesigning the cannon to remove some design elements that are artifacts of fullauto water cannons. I'll post some more pictures and test results soon.

As far as the magma mister or magma curtain, I'm still validating/invalidating "Plan A". Its simpler to setup and use then "Plan B".

[Chaine Maile]

The Bin made me wonder if throwing flaming spears or arrows would be fun too. They would need to last longer then the wooden bin did, to enable enough flight time to deal any damage.

[Chaine Maile]

Thinking about it some more I'm going to do hard !!SCIENCE!! on duration of magma exposure required to ignite contents in Ticks. It would definitely be useful for the Wiki. My working theory is different amounts of submersion transfer more or less heat.

[Chaine Maile]

Looking around more on the Wiki showed each material has a Specific Heat value, which determines how quickly or slowly it changes temperature. If the specific heat is degrees Urist per Tick it should be very quick, maybe 5.17 ticks? 517 is certainly not what I have observed, but I'll run more tests to confirm.

LIGNITE (also coke and charcoal)
[SPEC_HEAT:409]
[IGNITE_POINT:11440]

IRON
[SPEC_HEAT:450]

STEEL
[SPEC_HEAT:500]

[cyberTripping]

Specific heat is how much energy is needed to raise a gramme of the material a degree urist.
 Considering there's no clear dorf-joule, I'm not sure what the numbers could represent. This demands science.

[Chaine Maile]

Rough findings had the Willow Bin vanish at 330 ticks. It had "x" on 200, and "XX" on 300. It never caught fire, it simply vanished from damage.

The Coke/Charcoal ignited at 460 Ticks, but the ones inside the wooden bin didn't also light even after an additional 250 Ticks. It appears the willow bin prevented any heat transfer to the few bars inside it.

When I did previous testing the other day I must have made a mistake and unpaused at some point. It's definitely in the hundreds of Ticks. I'll make a 10 Tick macro and confirm my counts again tomorrow. It's very interesting how close the first sample ran to the specific heat of the iron minecart.

[Quietust]

Specific heat is how much energy is needed to raise a gramme of the material a degree urist.
 Considering there's no clear dorf-joule, I'm not sure what the numbers could represent. This demands science.

Try reading my post above - I've already done the science for you.

Granted, the numbers I posted were for lignite being heated by magma when lying on the floor - if they're in a minecart, then it will likely take longer because there will be additional heat transfer between the minecart and its contents. In particular, the magma will likely only directly heat the minecart itself, and then the heat from the minecart will transfer into the items inside (which will itself reduce the temperature of the minecart, making it take even longer).

[Chaine Maile]

Yeah, I had read it but neglected the specific heat portion. I isolated my mistake that caused the contradiction.

Basically, the 1 unit of magma had been heating the cart for some time. I didn't clean or let anything cool, simply added more magma. Coincidence had it so it was right on the verge of lighting, and just needed a few more ticks. Sorry for the mistake and confusion. I should have done a full clean start between the 1 unit and 7 units.

How exactly does heat transfer between Iron Minecart and a Bin containing fuel? I'm pretty confused by how the contents of the bin were apparently shielded from any exposure.

[TheHossofMoss]

Any luck with testing this Chaine Maile?

[Stopkilling0]

Why dont you fire the boulder through a really long "barrel" that is constantly being pumped full of magma, long enough so that by the end it is on fire. Make the entire bottom the the barrel out of grates and have a ton of magma waterfalls cycling magma through