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Is it expected for the cruising speed of a plane to change based on its location?

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Question

If we have a plane that is cruising around the world at a specific altitude, at max thrust, and with infinite propellant turned on, would it be normal for its cruise speed to change depending on where it is? I'm observing that the cruise speed does change, so maybe something like the Coriolis force, or maybe the air temperature, is affecting it somehow?

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The density in the alt-F12 aero-data display changes ±1.5% with time of day, in a way consistent with temperature, so I presume it changes as temperature changes with location.

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KSP does model the effect of air density, so temperature could have a small effect on airspeed.  You'll need to share specific numbers if you want to discuss the cause.
Not the Coriolis force, though; that acts to the side, and KSP uses rotating frames that cause it to ignore this force. (Foucault pendulums don't precess.)

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51 minutes ago, OHara said:

KSP does model the effect of air density, so temperature could have a small effect on airspeed.

But does it model density in relation to temp?   I've never done a log of temps at various locations, does it even change based on location at all?

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6 minutes ago, OHara said:

The density in the alt-F12 aero-data display changes ±1.5% with time of day, in a way consistent with temperature, so I presume it changes as temperature changes with location.

Yes, I see now that the air density is slightly changing. Over the South Pole the density was greatest, and the speed was highest, which makes sense since cold air is denser than warm air.

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11 hours ago, Gargamel said:

But does it model density in relation to temp?   I've never done a log of temps at various locations, does it even change based on location at all?

Kerbin's temperature varies with latitude, altitude, and time of day.  I do not know whether the white regions at the peaks of mountains correspond to a temperature of 273 K (though I doubt it; the atmosphere was overhauled but not the terrain), but I do know that sea level at the equator is usually in the neighbourhood of 310 K and the poles tend to be closer to 240 K.  I'm certain that exact values exist, but I am not certain of where to find them.

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