Difference between revisions of "Plane"

From Kerbal Space Program Wiki
Jump to: navigation, search
(*higher record; +air launch to orbit;)
m
 
(24 intermediate revisions by 6 users not shown)
Line 1: Line 1:
[[File:SPH Runway and Ravenspear Mk1.png|thumb|A [[Ravenspear Mk1]] starting from the runway.]]
+
[[File:IconPlane.png|left|link=]]
A '''plane''' is a [[craft]] which starts horizontally and utilises the lift generated from [[wing]]s or [[winglet]]s. Because planes usually use [[jet engine]]s they are more efficient than [[rocket]]s but normally don't leave the [[atmosphere]]. Therefore, long distances can easily be covered in-atmosphere, but on the other hand the atmosphere induces drag at all times, preventing a stable [[orbit]].
+
[[File:SPH Runway and Ravenspear Mk1.png|thumb|A [[Ravenspear Mk1]] taking off from the [[Runway]] in {{Version|1.0.5}}.]]
 +
A '''plane''' is any [[craft]] which flies horizontally in an [[atmosphere]] utilizing [[lift]] primarily generated by [[wing]]s, [[winglet]]s, or [[control surface]]s. Such flight involves [[w:Lift-induced_drag|lift-induced drag]], but reduces the total thrust required to traverse a distance at a given speed.
  
Planes are build in the [[Space Plane Hangar]] and start from the [[runway]]. It is possible to build planes in the [[Vehicle Assembly Building]] but from there planes would start on the [[launch pad]], whose small size makes a horizontal takeoff difficult. There are various [[stock craft|stock planes]] available in the Space Plane Hangar.
+
Along with [[rocket]]s, planes are one of KSP's most commonly referenced kinds of vessel, although it is not explicitly a [[Craft#Vessel_types|vessel type]].
  
The fastest known plane moved at about 2377&nbsp;m/s relative to the ground a bit short of Mach 7 in [[0.23]].<ref>“[[thread:27296|The MachingBird Challenge!]]” in the forums.</ref> At this speed it is possible to circumnavigate [[Kerbin]] in about 29 minutes at an altitude of 40&nbsp;km. For comparison the speed required to orbit Kerbin at 70&nbsp;km (outside the atmosphere) is only 2296&nbsp;m/s.
+
== Usage ==
 +
Planes are highly efficient for traversing [[Kerbin]] and, after an interplanetary journey, other celestial bodies with sufficient atmosphere. They are ideal for [[contracts]] taking place on Kerbin.
  
Another hazard to planes are flameouts, which occur when not enough [[intake air]] is available, especially when there are engines generating thrust off the [[center of mass]]. This could lead to an unstable flight, when only engines on one side fail and engines on the other side continue to generate thrust applying torque.
+
Spacecraft can be launched more efficiently in terms of both fuel and recoverable parts by designing craft which fly as planes while lower in the atmosphere or having an aerodynamic mothership for [[w:Air launch to orbit|air launch to orbit]] rockets, though sufficient altitude at separation is required to avoid the mothership being deleted.
  
== Variants ==
+
== Construction ==
It is possible to build planes which can leave the atmosphere and achieve orbit. Those planes are called [[spaceplane]]s and require a [[rocket engine]] to finish the orbit.
+
As a rule, planes are built in the [[Spaceplane Hangar]] and takeoff horizontally (STOL) from the [[Runway]]. Planes can be built in the [[Vehicle Assembly Building]], but the [[Launch Pad]] is inferior for horizontal takeoff and offers no advantage for vertical takeoffs.
  
Another form of planes are gliders. Those don't use any fuel to propel them and simply exchange height with velocity. As there is no weather, no updrafts exist, so gliders can't ascend without losing speed. Launching gliders can also be problematic. However, the aerodynamics system can also be exploited to produce [[infinite glider]]s, which accelerate without the use of engines.
+
[[Center of lift]] and its position relative to [[center of mass]] is crucial to aerodynamics. Positioning and angling of the wings and other aerodynamic parts can be a complex process. Also, fuel consumption during flight tends to shift the center of mass. Care must be taken during construction that the lower mass of the tanks doesn't move the center of mass too far from the center of lift.
  
== Air launch to orbit ==
+
Also, keeping the [[center of thrust]] at least roughly co-planar with the center of mass is vital. Otherwise, attitude control (pitch, yaw, or roll) and [[SAS]] have to compensate to maintain level flight.
{{See also||{{Wikipedia|Air launch to orbit}}}}
 
[[Rocket]]s could be carried higher into the atmosphere by planes to use the more efficient jet engines for part of the way. Because the rocket then starts higher up, the drag by the atmosphere is lower and the engines do work more efficient. A plane also imparts momentum on the rocket prior to the rocket launching. The plane must also carry the rocket which limits it size and mass. Also releasing the rocket is tricky, although [[Sepratron I|Sepratrons I]] can assist in pushing the rocket from the plane.
 
  
Airplanes should reach altitudes between 15 and 20 kilometers to be effective and reach speeds up to 1000 m/s at release to reduce the speed which is required by the rocket. To keep the rocket's mass and size low only one or two stages are recommended.
+
== Categories ==
 +
=== Airplane ===
 +
Airplanes are planes designed to remain within an atmosphere. Jet engines are by far the most common choice due to efficiency. If an airplane uses rocket engines instead, it is a '''rocket-plane'''.
 +
 
 +
=== Seaplane ===
 +
A plane able to land on and take off from bodies of water is considered a seaplane.
 +
 
 +
=== Spaceplane ===
 +
A plane which can leave the atmosphere and achieve orbit is a [[spaceplane]]. Doing so requires another source of thrust besides jets to ascend out of the upper atmosphere, most commonly [[rocket engine]]s.
 +
 
 +
=== VTOL ===
 +
Applicable to any kind of vehicle, the ability for “Vertical Take-Off and Landing” is accomplished by having engines which point downward and are balanced around the Center of Mass. These may or may not be the main engines used in horizontal flight. Care and skill are required to brake forward momentum in flight to achieve a landing. Most consider it necessary for engines rather than parachutes to be used for landing.
 +
 
 +
=== Glider ===
 +
A plane without thrust is a glider. This may be a plane designed without engines which detaches from another lifting vehicle, or an airplane possessing a stable glide path after exhausting its fuel similarly to the real-life NASA Space Shuttles. Gliders exchange altitude for velocity. As there is no weather in KSP, no updrafts exist, so gliders can't ascend without losing speed. Before [[1.0]] the aerodynamics system could also be exploited to produce [[infinite glider]]s, which accelerate without the use of engines.
 +
 
 +
=== Mothership ===
 +
A mothership plane is one which is used to carry another vessel(s), typically a rocket, to higher altitudes before it launches. The real-world [[w:Pegasus (rocket)|Pegasus]] rocket is an example of this launch profile, where a “[[w:Stargazer (aircraft)|Stargazer]]” [[w:Lockheed L-1011 TriStar|L-1011]] carries the rocket into the air.
 +
 
 +
== Operation ==
 +
Planes usually take advantage of [[jet engine]]s, which require [[air intake]]s to breathe in atmospheric [[oxygen]], allowing them to forego carrying the weight of [[oxidizer]] needed by [[Reaction_engine#Liquid_fuel_rocket_engines|rocket engines]]. Jet engines are fuel-efficient, thus great distances can easily be covered within atmosphere.
 +
 
 +
For a given set of engines at a given throttle level, there is a minimum amount of intake air which must be constantly collected by the air intakes. Collecting more air does not improve performance, but falling below the minimum amount results in one or more engines suffering a “flameout” and shutting down. Planes often have jet engines paired in bilateral symmetry, but it's rare both engines flameout simultaneously. Thrust then becomes asymmetrical about the plane's [[center of mass]], applying turning torque that can easily cause a “flat spin” like a frisbee. Planes often have difficulty regaining control and thus may land in multiple pieces, if any.
 +
 
 +
Altitude is vitally important to operating jet engines. At lower altitudes, intake air is more available but drag also is greater, limiting top speed. As altitude increases, there is decreasing intake air available as well as less drag. Decreasing drag allows higher speeds which allows more intake air to be collected. However, increasing throttle position to gain speed increases the total required intake air to avoid a flameout. There is also decreasing lift, requiring a plane to pitch higher to avoid falling, which may decrease the efficiency of air intakes. A jet plane's ability to balance these competing demands defines its operational ceiling. On Kerbin, the highest that even supersonic jets can meet minimum intake requirements is around 40&nbsp;km.
 +
 
 +
Planes operating above the range of jet engines require secondary propulsion, typically rocket engines. Such planes are called “[[spaceplane]]s” as in the name of the [[Spaceplane Hangar]]. Atmospheric drag still prevents achieving [[orbit]] unless and until the plane is able to fully clear the atmosphere. On Kerbin this is around 70&nbsp;km.
 +
 
 +
=== Flight records ===
 +
The fastest known plane demonstrated, in {{version|0.23}}, a top speed of about 2377&nbsp;m/s relative to Kerbin's surface — just short of Mach 7.<ref>“[[thread:27296|The MachingBird Challenge!]]” in the forums.</ref> At this speed it is possible to circumnavigate [[Kerbin]] in about 29 minutes at an altitude of 40&nbsp;km. For comparison the speed of a stable [[LKO|Low Kerbin Orbit]] at 70&nbsp;km (outside the atmosphere) is only 2296&nbsp;m/s. Because the craft at that speed is faster than the orbital velocity of that height the craft naturally tends to rise.
  
 
== Notes ==
 
== Notes ==

Latest revision as of 14:32, 23 February 2017

IconPlane.png
A Ravenspear Mk1 taking off from the Runway in version 1.0.5.

A plane is any craft which flies horizontally in an atmosphere utilizing lift primarily generated by wings, winglets, or control surfaces. Such flight involves lift-induced drag, but reduces the total thrust required to traverse a distance at a given speed.

Along with rockets, planes are one of KSP's most commonly referenced kinds of vessel, although it is not explicitly a vessel type.

Usage

Planes are highly efficient for traversing Kerbin and, after an interplanetary journey, other celestial bodies with sufficient atmosphere. They are ideal for contracts taking place on Kerbin.

Spacecraft can be launched more efficiently in terms of both fuel and recoverable parts by designing craft which fly as planes while lower in the atmosphere or having an aerodynamic mothership for air launch to orbit rockets, though sufficient altitude at separation is required to avoid the mothership being deleted.

Construction

As a rule, planes are built in the Spaceplane Hangar and takeoff horizontally (STOL) from the Runway. Planes can be built in the Vehicle Assembly Building, but the Launch Pad is inferior for horizontal takeoff and offers no advantage for vertical takeoffs.

Center of lift and its position relative to center of mass is crucial to aerodynamics. Positioning and angling of the wings and other aerodynamic parts can be a complex process. Also, fuel consumption during flight tends to shift the center of mass. Care must be taken during construction that the lower mass of the tanks doesn't move the center of mass too far from the center of lift.

Also, keeping the center of thrust at least roughly co-planar with the center of mass is vital. Otherwise, attitude control (pitch, yaw, or roll) and SAS have to compensate to maintain level flight.

Categories

Airplane

Airplanes are planes designed to remain within an atmosphere. Jet engines are by far the most common choice due to efficiency. If an airplane uses rocket engines instead, it is a rocket-plane.

Seaplane

A plane able to land on and take off from bodies of water is considered a seaplane.

Spaceplane

A plane which can leave the atmosphere and achieve orbit is a spaceplane. Doing so requires another source of thrust besides jets to ascend out of the upper atmosphere, most commonly rocket engines.

VTOL

Applicable to any kind of vehicle, the ability for “Vertical Take-Off and Landing” is accomplished by having engines which point downward and are balanced around the Center of Mass. These may or may not be the main engines used in horizontal flight. Care and skill are required to brake forward momentum in flight to achieve a landing. Most consider it necessary for engines rather than parachutes to be used for landing.

Glider

A plane without thrust is a glider. This may be a plane designed without engines which detaches from another lifting vehicle, or an airplane possessing a stable glide path after exhausting its fuel similarly to the real-life NASA Space Shuttles. Gliders exchange altitude for velocity. As there is no weather in KSP, no updrafts exist, so gliders can't ascend without losing speed. Before 1.0 the aerodynamics system could also be exploited to produce infinite gliders, which accelerate without the use of engines.

Mothership

A mothership plane is one which is used to carry another vessel(s), typically a rocket, to higher altitudes before it launches. The real-world Pegasus rocket is an example of this launch profile, where a “StargazerL-1011 carries the rocket into the air.

Operation

Planes usually take advantage of jet engines, which require air intakes to breathe in atmospheric oxygen, allowing them to forego carrying the weight of oxidizer needed by rocket engines. Jet engines are fuel-efficient, thus great distances can easily be covered within atmosphere.

For a given set of engines at a given throttle level, there is a minimum amount of intake air which must be constantly collected by the air intakes. Collecting more air does not improve performance, but falling below the minimum amount results in one or more engines suffering a “flameout” and shutting down. Planes often have jet engines paired in bilateral symmetry, but it's rare both engines flameout simultaneously. Thrust then becomes asymmetrical about the plane's center of mass, applying turning torque that can easily cause a “flat spin” like a frisbee. Planes often have difficulty regaining control and thus may land in multiple pieces, if any.

Altitude is vitally important to operating jet engines. At lower altitudes, intake air is more available but drag also is greater, limiting top speed. As altitude increases, there is decreasing intake air available as well as less drag. Decreasing drag allows higher speeds which allows more intake air to be collected. However, increasing throttle position to gain speed increases the total required intake air to avoid a flameout. There is also decreasing lift, requiring a plane to pitch higher to avoid falling, which may decrease the efficiency of air intakes. A jet plane's ability to balance these competing demands defines its operational ceiling. On Kerbin, the highest that even supersonic jets can meet minimum intake requirements is around 40 km.

Planes operating above the range of jet engines require secondary propulsion, typically rocket engines. Such planes are called “spaceplanes” as in the name of the Spaceplane Hangar. Atmospheric drag still prevents achieving orbit unless and until the plane is able to fully clear the atmosphere. On Kerbin this is around 70 km.

Flight records

The fastest known plane demonstrated, in version 0.23, a top speed of about 2377 m/s relative to Kerbin's surface — just short of Mach 7.[1] At this speed it is possible to circumnavigate Kerbin in about 29 minutes at an altitude of 40 km. For comparison the speed of a stable Low Kerbin Orbit at 70 km (outside the atmosphere) is only 2296 m/s. Because the craft at that speed is faster than the orbital velocity of that height the craft naturally tends to rise.

Notes

  1. The MachingBird Challenge!” in the forums.