See bottom for results/findings... First two paragraphs are just me making mistakes.I cast a 7x7x5 submarine
I dug out from the roof a tunnel straight down through floors 1,2,3,4 and hollowed out floors 2,3,4.
I then trapped a miner in floor 4 behind some walls , poured in some water and then recast the stairs square and retunneled it using the trapped miner.
repeated for floors 2 and 3.
I then recast the roof.
Finally i had my shell ready to drop into magma as you describe! I saved the game and deconstructed the support.
As expected the roof collapsed down the way crushing the floors and water, leaving no evidence of the brave trapped miner dwarfs or the submarine. I was left with a a 7x7x3 pile of obsidian at the bottom of the magma with a raised outer area another 2z levels up.
... What did I do wrong?
Some save scumming + dfhack experiments:
- I quit and reloaded and tried again using dfhack to replace my water with 5/7. This resulted in the same result but with a 1 tile wide obsidian column rising up to the surface.
- 7/7 water caused 2 1 tile columns in each corner to appear.
- I put SMR at the bottom and the whole thing was swallowed up with no remains (5/7) water.
- Replaced the diving area to be water instead of magma. Tried bottom floor water, top two floors magma, ended up with a 7x4 obsidian block at the 'ocean' floor.
- Removed my stone wall roof and replaced it with JUST a obsidian floor. Getting BETTER results, 6 pillars this time but still no enclosed area.
- Removed my stone wall floor and replaced it with JUST a obsidian floor. Got the desired result. using 2/7 water! finally!
For anyone trying this the submarine MUST BE like so:- floors (can be made of anything, as long as it will deconstruct). No roof is needed, but 2/7 water is required on top floor
- Shell, must be CAST obsidian walls OR normal unmined stone (including edge of top and FLOOR of bottom level
List of my findings:
- Doesn't work if you replace magma with water (and use magma in the container instead)
- All items on top/in the submarine end up on top of it, and any dwarfs inside get insta gibbed as expected... A more cunning plan is needed
- Any items placed on the landing zone get crushed/encased in obsidian by the submarine and disappear.
- only works if you are dropping the submarine into magma above a floor... doesn't working over SMR.
- doesn't matter how much water you use, as long as there is at least 2/7 on THE TOP FLOOR
- you can make your tower hollow over multiple z levels... just make your submarine taller
- It doesnt matter how many z levels above the drop zone your submarine is, it can be 1 or any number higher
- NO roof is needed, just walls to contain the water
Based on my findings
I don't believe there is any way to use this to get dwarfs to the bottom of the sea/magma sea. However it COULD create a great way to quickly make a fortress in the middle of a volcano. (Requires Dfhack to remove the SMR at the bottom? unless we can find a way around that)
Edit:
OKAY so after an afternoon actually doing my job rather than throwing dwarfs into magma trenches I've come up with some avenues for further exploration. We have three problems to solve in this field of science:
1. Can you make a dwarf survive a trip through several z levels of magma in any way?
2. Can you make a lever which times the dwarfs exit and then very specifically does another action after a series of ticks (collapses a support) OR can we predict how many ticks a miner at mining level X will take to channel a square they are next to?
3. Can you make a submarine land safely on the SMR.... I think the OP has already done this but I don't understand how.
The plan is to launch a dwarf down through the magma and 'capture' them mid flight inside our quantum submarine which can move between one location and the next in a single tick. I'm thinking it would be best to use minecarts as then hopefully (if they don't get destroyed by magma) you can also transport everything our dwarf is going to need for their adventure. Pickaxe, axe, seeds, booze, minecarts full of water, etc.