Engine Config Curve Documentation

[Arrowstar]

Hi everyone!

Could someone point me to resource(s) that define and document what the various curves that modify engine performance are and how they work?  As of now I'm aware of the existence of with "atmosphereCurve", "velCurve", and "atmCurve".  Are there any others?  It would also be very helpful to know what the input and output of every curve is (with units) and how KSP applies those curves to its engine modeling.

Does this information exist anywhere?

Thanks!

[Manul]

On 3/13/2020 at 1:27 AM, Arrowstar said:

It would also be very helpful to know what the input and output of every curve is (with units) and how KSP applies those curves to its engine modeling.

For atmosphere curve
X: atmosphere pressure (atm)
Y: engine isp (s)

velCurve
X: Mach number
Y: Thrust multiplier

atmCurve
X: pressure (atm)
Y:Thrust multiplier

velCurveIsp       //This curve specified Isp% to mach relationship.
X: Mach number
Y: Isp multiplier

Each curve is defined by keys:
key = X  Y  Tangent In    Tangent Out

KSP approximates a current Y value for current velocity and ambient pressure. Thrust is multiplied by this value.

Edited March 14, 2020 by Manul

[Arrowstar]

2 hours ago, Manul said:

For atmosphere curve
X: atmosphere pressure (atm)
Y: engine isp (s)

velCurve
X: Mach number
Y: Thrust multiplier

atmCurve
X: pressure (atm)
Y:Thrust multiplier

velCurveIsp       //This curve specified Isp% to mach relationship.
X: Mach number
Y: Isp multiplier

Each curve is defined by keys:
key = X  Y  Tangent In    Tangent Out

KSP approximates a current Y value for current velocity and ambient pressure. Thrust is multiplied by this value.

Thank you! 

Do you know where or how KSP interpolates thrust as a function of atmosphere density/pressure?  In the engine data shown in the game, we see sea level and vacuum thrust levels, but these don't appear in your curves.

[Manul]

7 hours ago, Arrowstar said:

thrust as a function of atmosphere density/pressure?

For rocket engines thrust is calculated based on their isp (see atmosphereCurve). Jet engines have only one value in atmosphereCurve but they have atmCurve, thrust is simply multiplied by Y value of this curve.

[Arrowstar]

13 hours ago, Manul said:

For rocket engines thrust is calculated based on their isp (see atmosphereCurve). Jet engines have only one value in atmosphereCurve but they have atmCurve, thrust is simply multiplied by Y value of this curve.

Oh is the flowrate of the engine constant?

[Manul]

On 3/15/2020 at 10:46 PM, Arrowstar said:

Oh is the flowrate of the engine constant?

For rocket engines it's constant, for jet engines it's multiplied by thrust multiplier.