Difference between revisions of "Engine"

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(Rewrote for consistency with updated Reaction engine article)
(Wording changes for clarity & concision)
 
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An '''engine''' is a part to accelerate a craft. There are three different type of engines available which have different properties.
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An '''engine''' is a part that can accelerate a [[craft]]. There are three different types of engines available.
  
 
== Reaction engine ==
 
== Reaction engine ==
 
{{Main article|Reaction engine}}
 
{{Main article|Reaction engine}}
A reaction engine is based on Newton's third law: “for every action there is an equal and oppposite ''reaction''”. Reaction engines expel reaction mass outward along the exact opposite vector as the [[craft]] is accelerating along. This force can generally be called ''thrust''.
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A reaction engine is based on Newton's third law: “for every action there is an equal and opposite ''reaction''”. Reaction engines expel reaction mass in one direction (the action), which accelerates a [[craft]] in the exact opposite direction (the reaction). This generates a force known as ''thrust''.
  
 
To be more intuitive to KSP, this wiki considers reaction engines only to be those where thrust comes directly from expending fuel. There are five major types of reaction engine, one of which is technically a sub-type of another:
 
To be more intuitive to KSP, this wiki considers reaction engines only to be those where thrust comes directly from expending fuel. There are five major types of reaction engine, one of which is technically a sub-type of another:
 
* [[Jet engines]], which expend [[liquid fuel]] and [[intake air]]  
 
* [[Jet engines]], which expend [[liquid fuel]] and [[intake air]]  
 
* Liquid fuel rocket engines, which expend [[liquid fuel]] and [[oxidizer]]
 
* Liquid fuel rocket engines, which expend [[liquid fuel]] and [[oxidizer]]
** or Monopropellant engines, which expend [[monopropellant]]
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** Including Monopropellant engines, which expend [[monopropellant]]
 
* Solid fuel rocket engines, which expend [[solid fuel]]
 
* Solid fuel rocket engines, which expend [[solid fuel]]
 
* Ion engines, which expend [[xenon gas]] utilizing [[electric charge]]
 
* Ion engines, which expend [[xenon gas]] utilizing [[electric charge]]
Of note, jet engines can only work inside of an [[oxygen]]-rich [[atmosphere]], as intake air cannot be stored in any practical way. The rest are considered ''rocket engines'' as they can function in vacuum using only resources stored aboard the craft.
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Jet engines can only work inside of an [[oxygen]]-rich [[atmosphere]], as intake air cannot be stored in any practical way. The other four categories are considered ''rocket engines'' and can function in vacuum using only resources stored aboard the craft.
  
== Jet engine ==
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== Wheels ==
{{Main article|Jet engine}}
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A completely different type of engine is powered [[wheels]] (not including [[landing gear]]). These are used on [[rover]]s. Motors generate torque on the wheels, and if the wheels are in contact with a surface providing friction (as all solid objects in KSP do), they can accelerate a craft. They can easily accelerate away from surfaces unless a force such as gravity or centrifugal force keeps them in contact with it. Usually they are very slow compared to reaction engines, but powered wheels require only [[electric charge]] and can thus run indefinitely without refueling by another craft.
A jet engine intakes air, mixes it with [[liquid fuel]], and after combustion pushes exhaust gas out of a nozzle. They could work in weightlessness but need an oxygenated atmosphere to work, which is impossible to recreate in KSP. They are more efficient than rocket engines as the oxygen for combusting their fuel is gathered in-flight from outside air, not oxidizer carried onboard adding to total mass. These engines use only liquid fuel.
 
  
== Rover wheels ==
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In real life, powered wheels could technically be considered reaction engines that use the surface as a reaction mass. However, to be more applicable to KSP, this wiki requires reaction engines to consume reaction mass, not merely be adjacent to it.
A completely different type of engine are [[rover]] wheels. They can accelerate a craft in vacuum but they need friction with an surface to move along this surface, so they won't work in weightlessness but with artificial gravitation they can drive on the inner side of a centrifuge in weightlessness. Usually they are very slow compared to the fuel consuming engines but run only on [[electricity]] so that they can run forever as long as there is a generator on board.
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== SAS torque ==
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Though far from a standard propulsion technique, as powered wheels are more easily steered and less likely to be break at higher speeds, it is entirely possible to propel a terrestrial vehicle using the torque provided by [[SAS]] and [[reaction wheel]] modules. However, this torque spins the entire craft rather than just wheels in contact with the ground. Disc-shaped, cylindrical, or spherical craft can use this torque to roll across the surface with varying levels of Kerbalness. Rotation around less rounded profiles will tend toward flip-walking across the surface. Neither is likely to fast or safe, but it can easily be fun and possibly practical in certain circumstances.
  
 
[[Category:Engines]]
 
[[Category:Engines]]

Latest revision as of 09:36, 3 January 2024

An engine is a part that can accelerate a craft. There are three different types of engines available.

Reaction engine

→ Main article: Reaction engine

A reaction engine is based on Newton's third law: “for every action there is an equal and opposite reaction”. Reaction engines expel reaction mass in one direction (the action), which accelerates a craft in the exact opposite direction (the reaction). This generates a force known as thrust.

To be more intuitive to KSP, this wiki considers reaction engines only to be those where thrust comes directly from expending fuel. There are five major types of reaction engine, one of which is technically a sub-type of another:

Jet engines can only work inside of an oxygen-rich atmosphere, as intake air cannot be stored in any practical way. The other four categories are considered rocket engines and can function in vacuum using only resources stored aboard the craft.

Wheels

A completely different type of engine is powered wheels (not including landing gear). These are used on rovers. Motors generate torque on the wheels, and if the wheels are in contact with a surface providing friction (as all solid objects in KSP do), they can accelerate a craft. They can easily accelerate away from surfaces unless a force such as gravity or centrifugal force keeps them in contact with it. Usually they are very slow compared to reaction engines, but powered wheels require only electric charge and can thus run indefinitely without refueling by another craft.

In real life, powered wheels could technically be considered reaction engines that use the surface as a reaction mass. However, to be more applicable to KSP, this wiki requires reaction engines to consume reaction mass, not merely be adjacent to it.

SAS torque

Though far from a standard propulsion technique, as powered wheels are more easily steered and less likely to be break at higher speeds, it is entirely possible to propel a terrestrial vehicle using the torque provided by SAS and reaction wheel modules. However, this torque spins the entire craft rather than just wheels in contact with the ground. Disc-shaped, cylindrical, or spherical craft can use this torque to roll across the surface with varying levels of Kerbalness. Rotation around less rounded profiles will tend toward flip-walking across the surface. Neither is likely to fast or safe, but it can easily be fun and possibly practical in certain circumstances.