Difference between revisions of "Center of lift"

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m (added how to use the center of mass to predict how a plane might tilt in flight.)
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[[File:Col icon.png|framed|left|Icon]]
 
[[File:Col icon.png|framed|left|Icon]]
 
[[File:Com col cot.png|thumb|The center of lift within the center of mass indicator]]
 
[[File:Com col cot.png|thumb|The center of lift within the center of mass indicator]]
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The '''center of lift''' is one of three measurable forces in the [[Vehicle Assembly Building]] and [[Space Plane Hangar]]. Used mainly when creating [[plane]]s, it shows the axis and direction of lift provided by [[wing]]s, [[control surface]]s and [[winglet]]s. Inside the editor it is showed as a cyan-coloured sphere (axis) along with an arrow (direction of the lift).
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The '''center of lift''' (abbreviated '''COL''' or '''CoL''') is the point where the sum total of all [[lift]] generated by parts — principally by [[wing]]s, [[control surface]]s, and aerodynamic fuselage parts — balances out and the aggregate direction their force will act on a [[craft]] while in an [[atmosphere]].
  
== Uses in plane bulding ==
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Along with the [[center of mass]] (COM) and [[center of thrust]] (COT), it is one of three key physics properties determining a craft's behavior while in motion. Display of the COL can be toggled in the [[editor]] where it is seen as a cyan and black checkered sphere with a cyan arrow extending out of it.
The location of the center of lift (abbreviated CoL) in relation to a plane's [[center of mass]] defines the plane's behavior in flight. Depending on where the center of lift is placed, the consumption of fuel may affect the center of mass in such a way that the plane becomes back-heavy and very unstable over time. To counteract this, it's recommended to place the center of lift slightly behind the center of mass, as this will keep the plane stable throughout the flight despite the shifting weight of the fuel.
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== Using the center of lift ==
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== Usage ==
The center of lift can tell you how a plane will move in flight. If the lift is to far behind the center of mass then the plane will tip slightly forward, if it is to far forward then it will tip backwards. Similarly, if it is too far to the right it rolls left and if it is to the left it rolls right.
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Like [[w:Thrust|thrust]], lift is a force acting on a craft with its fulcrum at the center of mass. The COL has a vector arrow pointing the direction that lift will push through the COL, and thus which way it will tend to pitch (up or down), yaw (left or right), or even roll (clockwise or counterclockwise). This force becomes stronger the faster the craft goes and thicker the atmosphere is around it.
It is good to have it close to the center of mass to prevent tipping.
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It can alternatively be understood as the ''center of [[drag]]'' that forward momentum will try to place behind the COM like the feathers fall behind the head of an arrow in flight.
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=== Flight characteristics ===
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Different flight characteristics are desired in different craft. If the COL or the lift vector is positioned or pointing off-center left-to-right, the craft will turn. If the COL is positioned too far toward the bottom of the craft, it will want to roll over. Assuming the COL is centered side-to-side, and possibly top-to-bottom, performance is basically as follows:
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* COL ahead of COM → Flips or turns uncontrollably
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* COL inside COM → Excessively maneuverable; needs constant course correction
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* COL closely behind of COM → More maneuverable
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* COL further behind of COM → More stable
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* COL very far behind of COM → Very hard to correct course; likely to flip up or nosedive
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=== Shifting fulcrum ===
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The center of mass will shift as fuel is consumed or stages detach. This may critically alter the relation between the COM and COL to alter the flight characteristics. It is not possible to see the COM, or the other centers, outside the editor. However, using [[tweakable]]s in the editor to alter the fuel level or temporarily taking stages off, or both, will alter the position of the COM, and COL if staged parts generate lift. This can reveal issues that would cause nonstandard flight profiles before actually launching.  
  
 
== See also ==
 
== See also ==
 
* [[Center of mass]]
 
* [[Center of mass]]
 
* [[Center of thrust]]
 
* [[Center of thrust]]
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[[Category:Physics]]
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[[Category:Game interface]]

Latest revision as of 18:46, 17 March 2017

Icon
The center of lift within the center of mass indicator

The center of lift (abbreviated COL or CoL) is the point where the sum total of all lift generated by parts — principally by wings, control surfaces, and aerodynamic fuselage parts — balances out and the aggregate direction their force will act on a craft while in an atmosphere.

Along with the center of mass (COM) and center of thrust (COT), it is one of three key physics properties determining a craft's behavior while in motion. Display of the COL can be toggled in the editor where it is seen as a cyan and black checkered sphere with a cyan arrow extending out of it.

Usage

Like thrust, lift is a force acting on a craft with its fulcrum at the center of mass. The COL has a vector arrow pointing the direction that lift will push through the COL, and thus which way it will tend to pitch (up or down), yaw (left or right), or even roll (clockwise or counterclockwise). This force becomes stronger the faster the craft goes and thicker the atmosphere is around it.

It can alternatively be understood as the center of drag that forward momentum will try to place behind the COM like the feathers fall behind the head of an arrow in flight.

Flight characteristics

Different flight characteristics are desired in different craft. If the COL or the lift vector is positioned or pointing off-center left-to-right, the craft will turn. If the COL is positioned too far toward the bottom of the craft, it will want to roll over. Assuming the COL is centered side-to-side, and possibly top-to-bottom, performance is basically as follows:

  • COL ahead of COM → Flips or turns uncontrollably
  • COL inside COM → Excessively maneuverable; needs constant course correction
  • COL closely behind of COM → More maneuverable
  • COL further behind of COM → More stable
  • COL very far behind of COM → Very hard to correct course; likely to flip up or nosedive

Shifting fulcrum

The center of mass will shift as fuel is consumed or stages detach. This may critically alter the relation between the COM and COL to alter the flight characteristics. It is not possible to see the COM, or the other centers, outside the editor. However, using tweakables in the editor to alter the fuel level or temporarily taking stages off, or both, will alter the position of the COM, and COL if staged parts generate lift. This can reveal issues that would cause nonstandard flight profiles before actually launching.

See also