Steam Engines

## Overview

### *\*\*Steam engine page is still under construction and is using data from version 2.7.3.\*\**

Steam engines burn materials to make steam inside boilers, which flows through pipes to drive pistons, turning a crankshaft to produce engine power. They come in three size variants, small, medium, and large. While not as instant as a fuel engine or electric engine, when created properly a steam engine can be much more efficient than fuel while being much less heavy than batteries. While the primary output of a steam engine is engine power, there are parts that allow energy creation and parts that can directly power propulsion parts. Steam engines scale very well, with large steam engine complexes able to produce massive amounts of power.

## Output & Gearboxes

A steam engine starts with a gearbox. Steam engine parts don't mix (with a few exceptions). Depending on the size of the gearbox there is a maximum output. Those sizes are:

* Small gearbox: 50,000 engine power
* Medium gearbox: 100,000 engine power
* Large gearbox: 200,000 engine power

Any steam engine you create will be limited by the gearbox, so if you need additional power you will have to build more than one steam engine. This will create some additional cost and complexity, but will give the benefit of redundancy, which is a valuable trait in *From the Depths*.

## Input & Steam Generation

Steam engines burn resources to make steam inside boilers. 1,000 steam is created for every 1 material burned, no matter what size you're using. Steam controllers regulate the amount of steam created, while boilers attached to the controller create and hold steam. The controller size must match the boiler size. Boilers can be chained together to create and store more steam. The stats for each size are:

Steam Boiler Stats
 Medium Boiler
 Large Boiler

Small and medium boilers deliver steam by attaching a steam pipe to the end of the boiler. Large engines are unique, requiring a special *Large Boiler Connector* part on the boiler which has steam pipe attachments on both sides. The default behavior for a steam controller is to burn the maximum amount of material until the boilers are full of steam. After that it will only burn the amount of materials needed to maintain maximum steam in the boilers and maximum steam pressure (10) in the pipes. However, you can change the maximum burn rate in the steam controller settings, plus ACBs, breadboards, and LUA boxes can also control burn rates when configured properly. A common use for ACBs and steam controllers is making steam engines that create electricity when the battery value or percentage is below a certain point. When the value hits the threshold the steam controller will go to maximum burn rate, powering the steam engine and creating additional electricity. Once the battery value has increased to the desired level steam controller will drop back to 0% burn rate. It is possible for a steam boiler to not produce the max steam pressure of 10 when the steam engine is under load, but typically you want your steam engine always producing maximum pressure to give you the maximum engine power and highest efficiency.

## Engine Power Creation

### Gearbox & Cranks

The steam engine is a combination of multiple parts and works (somewhat) like a steam engine does in real life. The first piece is the *gearbox*, which was discussed in earlier section. You then attach cranks to the gearbox. *Cranks* are the center piece that all steam pistons connect to. They come in two versions, a standard crank and a cased crank. Regular cranks are only available for small and medium steam engines. Cased cranks are available for small, medium, and large steam engines and are more durable but cost double compared to a regular crank. Small cranks can have up to 4 pistons per crank, while medium and large cranks can have up to 3 pistons per crank. Multiple cranks attached to one gearbox creates a *crankshaft*, like you see in a real world car engine. It is possible to have a steam engine with only one crank, but it is uncommon and only for incredibly small vehicles or niche applications.

There are two additional parts that can be placed on the end of a crankshaft, which are available for all crank sizes. *Flywheels* build up and store the mechanical energy from the crankshaft, which can be used to power shaft generators, creating electricity from the mechanical energy of the flywheel/crankshaft. *Steam drills* can also be placed on a crankshaft, pulling mechanical power from the crankshaft to create damage against any blocks that hit the drill. The more power in a drill, the more damage it will do.

### Steam Pistons

Pistons receive the steam from the boilers and create mechanical power that spins the crankshaft, producing engine power at the gearbox. Each steam engine size has a corresponding piston size. The more steam pressure that is fed into a piston, the more power that piston will create. There is a maximum amount of steam a piston will use at max pressure and a maximum amount of power the piston will produce. Those stats are:

Steam Piston Stats
per second
Power Creation
Energy Creation
 Medium Piston
 Large Piston
(Parallel & Serial)

Pistons use the amount of steam needed to maintain the needed engine power. This means a piston on an engine with 5% load will use less steam than an engine at 90% load. Additionally, a piston will output a portion of the steam that is fed into it, which allows you to attach outputs from one piston into the input of another piston in a process called *compounding*. This increases the efficiency of the steam engine at the expense of creating a slightly larger engine.

\*Add numbers showing efficiency amounts and differential steam values. create a "best practices" list for building steam engines\*

## Transmissions and Steam Propellers

Information needed about powering steam propellers and the associated parts.

## Steam Turbines

Steam engines can produce electricity using a flywheel and shaft generator, but a more efficient method is to use a steam turbine. These are special parts that take team from boilers to directly create electricity. The effiiciency of a turbine is based on the number of blades spinning in the turbine, so the longer the turbine is the more efficient it is. Longer turbines don't create more electricity, they only become more efficient.

\*Add a chart showing efficiency rates for different lengths of turbines\*

## Other References

There are a handful of videos and Steam forum posts that discuss steam engines. Here are a few of the popular tutorials:

**Steam Engine Design by Ao Kishuba**, November 2020 - Comprehensive guide that breaks down crank and piston designs and explains the typical metrics for steam engines such as PPM and PPV. Has a link to a blueprint with example engines.

**Steam Engines Full Guide (From the Depths 2021) by Liv's Lab,** August 2021 - Comprehensive video about steam engines, Discusses all the components and breaks down the build process. Also performs a demo build at the end of the video.

**From The Depths INSTANT Tutorial: Steam Engines & Steam Power by GMODISM**, April 2022 - Quick guide that shows the basics of steam engines.

**From The Depths Steam Engine Tutorial - All about STEAM! by GMODISM**, September 2021 - Slightly older and longer video from GMODISM that explains the basics of stem engines.