Want to burn your enemies to a crisp, but hate the pain of waiting for magma to evaporate?
Dropping an object into magma creates a small cloud or magma mist, but I wanted to create a persistant mist. The most obvious answer was to drop a minecart repeatedly into the same patch of magma. I tried various designs, both linear and spiral, but finally I decided on a system using linear generators for maximum concentration. I also wanted to keep a 3 tile wide path into the fort.
This design is made up of 9 identical units arranged side-by-side, each flinging a minecart back and forth over the path to splash down into the magma, and create a mist. The minecart and the rollers are magma-safe, naturally.
Each unit is arranged as follows:
# ___ #
# #
#▲F###F▲#Where ▲ is an E or W track ramp facing inwards, with a roller also pointing inwards, and F is a constructed fortification. These are flooded with magma. 1 level above the path is a 3 tile EW track to keep the minecart airbourne.
Results are...
...somewhat underwhelming.
Undeterred, I tried a more compact design on the north gate:
z=-1
z=0
This design is made up of 6 self contained units, each firing a minecart north then south:
_____
# #
#▲F▲#The symbols are as before, with inward facing ramps/rollers, and a constructed fortification. The unit is roofed over to keep it compact, although this isn't strictly necessary. As long as the minecarts have wall to hit, whether at z=0 or z=1, they would fall back down.
This time results are...
...more promising.
So far, the only casualty is a passing war dog. I await the next siege with great anticipation.