40d:Windmill

A windmill is a machine component that provides power via wind on the surface of a fortress map. The power produced by each windmill depends on your location: 40, 20, or 0. Building a windmill uses 4 pieces of wood.

When it works

A windmill generates power under the following conditions:

1. Its center tile is outside.
2. The map has wind.
3. : Some maps have strong wind (40 power per windmill), some have weak wind (20 power), and some have no wind at all.
4. It is not connected to frozen machinery, such as a screw pump or water wheel in ice.

When all of these conditions are met, the windmill will produce power at its center square.

Construction

To place a windmill, all 8 of the outer tiles must have a floor ^[Verify], and the center tile places like other machinery. After the windmill is built, the 8 outer floors can be removed (if built) but cannot be channeled (if natural)^[Verify]. A floor below the center tile will collapse if disconnected, causing structural failure even if the windmill itself is supported by machinery below.

Variants

Standard windmill

1. Build outside, on flat ground.
2. Channel out a single tile, leaving the 8 tiles around it intact.
3. Dig a tunnel to the channeled square and place machinery in it.
4. Build the windmill on top of the channel.

Windmill tower

The "windmill tower" option is useful if you can't dig below your windmill (if, for example, there is a room or underground river there). This option is also often more power-efficient, as it often eliminates the need to transfer power between z-levels.

1. Build a 3×3 platform (or 8-tile ring) out of floors one level above the ground floor.
2. Build the windmill on top of the platform.
3. Directly beneath the windmill, on the ground floor, build a gear assembly.
4. Connect this assembly to horizontal axles, and power your machines.
5. If desired, remove excess floors/stairs.

Sunken windmill

You can build windmills underground if the central square in the windmill is "outside" (channel the roof away above it).

Windmill farm

Several windmills can be linked together via gear assemblies and axles. The first windmill needs a gear assembly beneath it. After that, each windmill will require one gear assembly beneath it and two axles to connect to the next windmill. On high-wind maps, this gives 35 power for the first windmill, and 33 power for each extra windmill. On low-wind maps, this is reduced to 15 power for the first and 13 power for additional windmills.

Using the power

Getting power out of a hanging windmill is straightforward. As long as the machinery it's hanging on is a vertical axle, gear assembly, or screw pump, it will be powered.

Windmills with stable foundations are harder. A vertical axle or gear assembly beneath the center tile should always be powered, but the actual behavior seems buggy or non-intuitive; if it doesn't work, try re-building the machinery below the windmill. A screw pump beneath the center tile does not seem to get power^[Verify].

Construction Examples

See Machinery/Examples.