The final version of steam engines is finally here! So lets go over the changes!

The difference between main power sources

• Fuel engines: versatile and the components are very cheap. If they arent consistently used at their maximum output they will cool down, and their efficiency will be above whats shown on the stat screens. Good for backups and craft with erratic power usage.
  
• Custom jet generators: efficient, but the components are very expensive to buy and have strict placement rules if you want to use their full potential. Very attractive if you already have a working jet engine, and just have to pay for the generator and some extra combusters/compressors. Cost-inefficient if they are consistently taking damage.
  
• Steam engines: very cheap components and they are much more compact than fuel engines with the same efficiency. No placement restrictions, but their efficiency drops sharply when they arent running at their maximum output. Good as the main power source of craft with consistent power usage.
  

• All components save the steam and kinetic energy they have when the craft is saved or pulled from play. On loading, everything is instantly restored to that point
  
• Boilers do not burn materials when they reached maximum pressure now, out of play resource usage is similar to the in-play one
  
• Crankshafts and multipurpose shafts are not separate anymore. If its a rod and it rotates it can connect to axis shift gears, propellers and drills.
  
• Reduction gears do not need to be and cant be stacked anymore. They were renamed to transmissions, see their pros and cons below
  
• The changes above hopefully emphasize the different pros/cons of steam and take away the focus from some usability problems
  

• Pistons and turbines have a fixed maximum steam throughput. How much steam can actually pass through them depends on the difference between input and output pressure (output pressure for turbines is 0)
  
• Pistons convert 40% of the steam passing through them to kinetic energy on the crankshaft, pass the remainder to their output
  
• Small turbines get 2 turbine blades for each body, large ones 1 blade for each body. How much steam they convert to kinetic energy depends on the input pressure, divided by the blade count. Lower pressure drop/blade = higher efficiency
  
• Piston and turbine output scales with the kinetic energy of the crankshaft or the turbines rotating assembly
  

• Crankshafts and turbines both slowly lose a portion of their kinetic energy over time. This loss is proportional to rotation speed (so more significant at lower outputs), could be thought of as a combination of friction/inefficiency from lubricants gunking up at lower temperatures
  
• Each gearbox, crank, piston, crank generator, flywheel and turbine blade increases maximum kinetic energy loss
  
• At maximum output, this loss is low enough for steam to handily beat fuel engines, but gets more significant when power needed drops. You can combat it by shutting off by cutting steam from the rotating components, but youll still lose their stored kinetic energy over time and have to respin them when they are needed
  

• Single-stage pistons and turbines now have decent stats, very high power density but low efficiency (still much higher efficiency than before)
  
• Feeding the piston outputs into another set of pistons or turbines adds another processing step and increases efficiency. Also reduces the pressure difference in the pistons whose output is reused, so total volume-efficiency goes down
  
• When you resuse piston steam you also add parts increasing kinetic loss, so how many steps are worth it depends on you crank size, layout and use-case. More stages mean noticeably higher kinetic loss: total output ratios
  
• This means your choice is between a dense+inefficient engine, or efficient+high volume one. The dense engine also has lower total mass and a lower portion of its output is kinetic loss, so tolerates changing demand better.
  

• Small crank lines are the most power-dense, all efficiency-improvements are dropped in favour of being compact so they also have the highest relative kinetic loss
  
• Medium cranks have similar raw output to small ones, but their relative kinetic loss is much lower.
  
• They are slightly less dense and more efficient and lose less at lower output. Also, have higher relative crank mass so their response times are slower
  
• Huge cranks are very efficient and have a low relative kinetic loss. Volume-efficiency is slightly lower but still very good to compensate for the awkward form-factor
  

• Each individual piston and crank adds the same base kinetic loss, so sharing cranks between multiple pistons means that loss is slightly lower relative to the total output. Can also make the crank lines harder to place, especially for large-huge pistons
  
• Turbines can be very conveniently fit anywhere, so their base stats are slightly lower than something like 12 huge pistons sharing 4 cranks
  

• Transmissions are single blocks that can take a fixed amount of kinetic energy/s from their input shaft and add it to their output. Their output shaft has a minor kinetic loss
  
• Transmission braking takes away kinetic energy at the same rate, wastes the kinetic energy taken from the output shaft
  
• Steam propeller thrust scales with their rotation speed
  
• Steam propellers can now be used directly on the crankshaft, reducing volume and removing the minor kinetic loss. Also means their rotation speed cant be directly controlled
  
• Transmissions max output: input shaft rotation speed ratio can be set on the transmission. Twice the output rotation speed for propellers means twice the thrust, but also 4 times the kinetic energy stored (responds slower and wastes more energy when braking)