A craft propelled by steam...
Simply put, this includes any of a wide variety of vehicles propelled by using heated water cannons and generating thrust from ejected steam.
There are several forms, though mixes are possible.
Direct steam propulsion: Edit
Some craft use steam jets as a direct means of accelerating a vehicle. This method is simple, light, and produces little drag. It is even possible to build rockets that can travel straight upward using this method.
Rocket car: Edit
A land vehicle directly propelled by steam jets and sitting on typically unpowered wheels. May or may not have other means of propulsion.
Rocket sled: Edit
A land vehicle directly propelled by steam jets and sitting on skids of some kind. Generally doesn't have other means of propulsion. Very simple and can be quite fast.
An air vehicle which can propel itself vertically on steam jets and uses this as its primary means of propulsion. May well have other means of propulsion or "landing legs."
A vehicle meant to function with gravity disabled and without relying at all on aerodynamic surfaces. Generally won't function in full gravity.
Rocket plane: Edit
A vehicle which uses steam jets in order to propel itself into a horizontal takeoff by aerodynamic lift. Generally flies extremely fast, much faster than planes that use propellers for propulsion.
Rocket planes specifically designed to operate above the freezing limit.
Rocket glider: Edit
A rocket-propelled aerodynamic craft which lacks the properties needed for sustained flight, but can glide longer by using steam jets. Basically, it's a heavier, draggier, slower rocket plane.
Indirect steam propulsion: Edit
Some craft use steam jets to power other mechanical devices and use those as a means to accelerate a vehicle. Many of these crafts use piston engines or spinner engines.
Piston engine car: Edit
The piston-engined car is essentially a car that operates the wheels on power coming from an engine in which one or more pistons are compressed and then a steam jet decompresses them, providing torque. Unlike pure-rocket cars, they can switch gears or divert the power elsewhere.
Spinner engine car: Edit
The spinner engine car is very simple: it has a driveshaft being rapidly rotated by steam jets and that powers the wheels. Compact variants are likely to be inefficient, but all variants are quite simple.
Rocket wheel: Edit
A wheel with steam jets on it. Torque from the jets allows the wheel to roll.
Spinner engine helicopter: Edit
A craft which takes off vertically using force from a rapidly spinning shaft of steam jets. to power a propeller.
Piston engine helicopter: Edit
A craft which takes off vertically using a piston engine to power a propeller.
Spinner engine plane: Edit
A prop airplane powered by a spinner engine.
Piston engine plane: Edit
A prop airplane which uses the power from a piston engine in order to power a propeller to generate forward thrust.
Propcars, Propsleds, and other: Edit
There are doubtless other ways this feature could be used for propulsion and types of vehicles it couled be used on. Any type of torque engine can power a prop, and a prop can be attached to a car or sled in order to accelerate it, much like how an airboat works in real life.