Velocity curve and atmosphere curve

[duncan1297]

I am trying to make some kind of ramjet type engine using the stock textures but i got confused by this part

atmosphereCurve
 	{
		key = 0 1200
		key = 0.3 2500
		key = 1 800
 	}
	velocityCurve
	{
		key = 0 0.5 0 0
		key = 1000 1 0 0
		key = 2000 0.5 0 0
		key = 2400 0 0 0
	}

what does this mean?

thanks for the help.

[Greys]

atmosphereCurve

{

Key = [Atmospheric Pressure] [iSP]

}

Atmospheric Pressure is measured in Atmospheres(Atm) where vacuum is 0 and 1 is the atmospheric pressure on Kerbin at Sea Level

ISP is the efficiency of the engine, it's a real fancy number made out of science and math, and is measured in seconds (don't ask, math)

velocityCurve

{

Key = [Velocity] [% of Max Thrust] [Junk] [Junk]

}

Velocity is measured in Meters per Seconds

% of Max Thrust is represented as a float value between 0 and 1, though technically you can leave that range but that'd be weird.

[duncan1297]

Thanks, i wonder what the point of the extra zeroes on the velocity curve is for.

[ferram4]

The extra zeroes specify the slope of the curve at that point; the first specifies the slope coming from the left, the other specifies it coming from the right. This can be used to specify the curve more exactly with fewer inputs.

The velocity curve also does not impact fuel consumption at all, only thrust. The fuel consumption is calculated using the rated thrust of the engine (max thrust at full throttle, min thrust at throttle off, linear interpolation in between), not the final thrust once it has been affected by the velocity curve. For the TurboFan code that you posted, at 2000 m/s it produces half of its rated thrust, while its fuel consumption assumes that it is producing its full rated thrust; basically, its true Isp gets cut in half while the indicated Isp stays where it is.

[Andersenman]

[Junk] [Junk]

Thanks, i wonder what the point of the extra zeroes on the velocity curve is for.

The extra zeroes specify the slope of the curve at that point; the first specifies the slope coming from the left, the other specifies it coming from the right.

NathanKell wrote an excellent explanation on this here:

[iNFO] KSP floatCurves and you - the magic of tangents.

[NathanKell]

While I appreciate being mistaken for the awesome Taverius, I'm not Taverius.

And this thread should probably go back to sleep.